Nuclear Physics News - NuPECC · 2019. 10. 17. · Nuclear Physics News Volume 21/No. 1 Vol. 21, No. 1, 2011, Nuclear Physics News 1 Nuclear Physics News is published on behalf of

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Volume 21, Issue 1January–March 2011

FEATURING:Laboratory Portrait: The Institut für Kernphysik at

Forschungszentrum Jülich • Feature Article: Long Range Structure of the Nucleon

Nuclear Physics NewsVolume 21/No. 1

Vol. 21, No. 1, 2011, Nuclear Physics News 1

Nuclear Physics News is published on behalf of the Nuclear Physics European Collaboration Committee (NuPECC), an Expert Committee of the EuropeanScience Foundation, with colleagues from Europe, America, and Asia.

Editor: Gabriele-Elisabeth Körner

Editorial BoardT. Bressani, Torino S. Nagamiya, TsukubaR. F. Casten, Yale A. Shotter, VancouverM. J. Garcia Borge, Madrid (Chairman) H. Ströher, JülichJ. Kvasil, Prague T. J. Symons, BerkeleyD. MacGregor, Glasgow M. Toulemonde, Caen

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CorrespondentsArgentina: O. Civitaresse, La Plata; Australia: A. W. Thomas, Adelaide; Austria: H. Leeb, Vienna; Belgium:G. Neyens, Leuven; Brasil: M. Hussein, São Paulo; Bulgaria: D. Balabanski, Sofia; Canada: J.-M. Poutissou,TRIUMF; K, Sharma, Manitoba; C. Svensson, Guelph: China: W. Zhan, Lanzhou; Croatia: R. Caplar, Zagreb; CzechRepublic: J. Kvasil, Prague; Slovak Republic: P. Povinec, Bratislava; Denmark: K. Riisager, Århus; Finland: M. Leino,Jyväskylä; France: G. De France, GANIL Caen; M. MacCormick, IPN Orsay; Germany: K. Langanke, GSI Darmstadt;U. Wiedner, Bochum; Greece: E. Mavromatis, Athens; Hungary: B. M. Nyakó, Debrecen; India: D. K. Avasthi, NewDelhi; Israel: N. Auerbach, Tel Aviv; Italy: M. Ripani, Genova; L. Corradi, Legnaro; Japan: T. Motobayashi, RIKEN;Mexico: J. Hirsch, Mexico DF; Netherlands: G. Onderwater, KVI Groningen; T. Peitzmann, Utrecht; Norway: J. Vaagen,Bergen; Poland: B. Fornal, Cracow; Portugal: M. Fernanda Silva, Sacavém; Romania: V. Zamfir, Bucharest;Russia: Yu. Novikov, St. Petersburg; Serbia: S. Jokic, Belgrade; South Africa: S. Mullins, Cape Town; Spain:B. Rubio, Valencia; Sweden: J. Nyberg, Uppsala; Switzerland: K. Kirch, PSI Villigen; United Kingdom: P. Regan,Surrey; USA: D. Geesaman, Argonne; D. W. Higinbotham, Jefferson Lab; M. Thoenessen, Michigan State Univ.; H. G. Ritter,Lawrence Berkeley Laboratory; G. Miller, Seattle.

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NuclearPhysics

News

2 Nuclear Physics News, Vol. 21, No. 1, 2011

Cover illustration: The Coder Synchrotron COSY-Jülich with the three major internal experiments ANKE, PAX, andWASA.

Volume 21/No. 1

Contents

Editorial .............................................................................................................................................................. 3Laboratory PortraitThe Institut für Kernphysik at Forschungszentrum Jülich

by Markus Büscher, Andreas Lehrach and Frank Goldenbaum .................................................................... 5Feature ArticleLong Range Structure of the Nucleon

by Marc Vanderhaeghen and Thomas Walcher ............................................................................................14Facilities and MethodsExtreme Light Infrastructure–Nuclear Physics (ELI–NP): New Horizons for Photon Physics in Europe

by Dietrich Habs, Toshiki Tajima and Victor Zamfir....................................................................................23Impact and ApplicationsLaboratory of Neutron Activation Analysis at the Nuclear Physics Institute of the ASCR, Rež

by Jan KuCera ................................................................................................................................................30Meeting ReportsReport on the FINUSTAR3 Conference

by Sotirios V. Harissopulos and Rauno Julin ................................................................................................36Nuclear Structure 2010

by Roderick Clark ..........................................................................................................................................36News and views .................................................................................................................................................38Calendar ............................................................................................................................................................40

editorial


The views expressed here do not represent the views and policies of NuPECC except where explicitly identified.

NuPECC Long Range Plan 2010—Perspectives of Nuclear Physics in Europe

As announced in the April–June2009 issue of the Nuclear PhysicsNews International, the Nuclear Phys-ics European Collaboration Committeeof the European Science Foundationhave now published their ForwardLook on Nuclear Physics in Europe ata Presentation Conference in Brussels(under the Belgian EU Presidency) on9 December 2010.

The goal of the NuPECC LongRange Plan 2010 was to bring togetherthe entire Nuclear Physics communityin Europe to formulate a coherent planof the best way to develop the field inthe coming decade and beyond.

Nuclear Physics projects are often“big science,” which implies large

investments and long lead times. Theyneed careful forward planning andstrong support from policymakers.The Long Range Plan 2010 providesan excellent tool to achieve this. Itrepresents the outcome of detailedscrutiny by Europe’s leading expertsand will help focus the views of thescientific community on the mostpromising directions in the field andcreate the basis for funding agenciesto provide adequate support.

The full Long Range Plan 2010 canbe found at http://www.nupecc.org/,together with a booklet and a videothat presents the case to the educatedpublic. The report is based on the workof six expert sub-committees in the

fields of Hadron Physics, Phases ofStrongly Interacting Matter, NuclearStructure and Dynamics, FundamentalInteractions, and Nuclear PhysicsTools and Applications.

The main outcome of the exercisewas a list of recommendations groupedunder seven headers and shown belowin an abbreviated version.

ESFRI Facilities Complete in a timely fashion the

construction of the nuclear physicsfacilities on the ESFRI list of large-scale research infrastructure projectsin Europe:

a. FAIR at the GSI site, including itsfour pillars, the PANDA antipro-ton experiment, the NuSTARradioactive ion beam (RIB) facil-ity, the CBM dense baryonic mat-ter experiment, and the atomic,plasma, and applied physics pro-gram APPA.

b. SPIRAL2 at GANIL, includinghigh-intensity stable ion beamsand ISOL RIBs to study exoticnuclei.

Major Upgrades Carry out major upgrades of the

following complementary large-scalenuclear physics facilities:

a. HIE-ISOLDE at CERN (RIBs). b. SPES at INFN-LNL (RIBs). c. The AGATA γ-ray detector to be

used at the above facilities. Figure 1. Roadmap for Nuclear Physics research infrastructure in Europe.

editorial


d. The Superconducting Linac at GSIto provide high-intensity stable ionbeams for superheavy elementsstudies, for example.

ALICE Facility Upgrade the nuclear beams pro-

gram and the ALICE detector atCERN to extend the physics reach ininvestigations of quark-gluon matter.

Theory Strengthen the theory support to

experiment by developing collabora-tion between national theory groupsthrough new transnational programs:

a. Strengthen the financial basis of thetheoretical research infrastructureECT* to increase its involvementin European theory initiatives.

b. Strongly support advanced studiesrelated to the above experimentalrecommendations and improve thelink between nuclear theory andquantum chromodynamics.

c. Invest in high-performance comput-ing facilities dedicated to nuclearphysics projects.

Existing Facilities Fully exploit and upgrade existing

large-scale research infrastructures(listed below in north to south order)to exploit fully past investment:

a. The lepton beam facilities at ELSA,MAMI, CERN-COMPASS, andDAΦNE (INFN-LNF).

b. The hadron beam facilities at FZJuelich-COSY and GSI.

c. The heavy ion beam facilities atJYFL, KVI, GSI, GANIL, IPN,

CERN-ISOLDE, INFN-LNL, andINFN-LNS.

d. The nuclear astrophysics under-ground accelerator LUNA at INFNGran Sasso.

e. The ELENA upgrade of the Anti-proton Decelerator at CERN.

Fully exploit smaller-scale nationaland university nuclear physics labora-tories in Europe.

Applications and Education Secure and further develop the

nuclear physics skills base in view ofcurrent and future needs, in particularregarding:

a. Novel developments in energygeneration (nuclear fission andnuclear fusion), medicine (such asimaging and tumour therapy) andsecurity.

b. Development of novel sources,micro-beams, high-power targets,and radiation detection instrumen-tation that will also be used inother fields of science and engi-neering, and in the life sciences.

Future Facilities Continue the scientific and tech-

nical assessments for building newlarge-scale nuclear physics facili-ties in the future, and specificallypromote:

a. The inclusion of the high-intensityISOL facility EURISOL in futureupdates of the ESFRI list, based onthe successful EURISOL DesignStudy in the EU FrameworkProgramme 6.

b. Technical Design Studies for theintense RIBs facility ISOL@MYRRHA, a polarized proton-antiproton collider (PAX) and anelectron-nucleon/ion collider (ENC)at FAIR, and a high-energy electron-proton/ion collider (LHeC) at CERN.

c. The inclusion of nuclear physicsprograms at the multi-purposefacilities ELI (Extreme LightInfrastructure) and ESS (EuropeanSpallation Source).

This list of recommendations wasthen further condensed down into aroadmap for building new large-scaleNuclear Physics research infrastruc-ture in Europe as shown in Figure 1,where facilities whose first phaseshave already been approved are col-ored in blue, future upgrades thereofin dark blue, and those that are still inthe design or R&D phase in magenta.

GÜNTHER ROSNER

NuPECC ChairUniversity of Glasgow

Scotland, UK

laboratory portrait


The Institut für Kernphysik at Forschungszentrum Jülich

The Forschungszentrum Jülich(FZJ) pursues interdisciplinaryresearch that aims to solve the grandchallenges facing society in the fieldsof health, energy, and the environ-ment, and also information technolo-gies. In combination with its two keycompetencies—physics and super-computing—work at Jülich focuseson both long-term, fundamental, andmultidisciplinary contributions to sci-ence and technology as well as onspecific technological applications.With a staff of about 4,500, Jülich—amember of the Helmholtz Associa-tion—is one of the largest researchcenters in Europe. Located south-eastof the city of Jülich it is close to thecenter of a triangle formed by theGerman cities of Aachen, Düsseldorf,and Cologne.

The Institut für Kernphysik(Nuclear Physics Institute; IKP) isdedicated to fundamental research inthe field of hadron, particle, andnuclear physics. The aim is to studythe properties and behavior of lighthadrons in an energy range thatresides between the nuclear and thehigh-energy regime.

The primary facility at the IKP isthe COoler SYnchrotron COSY, amedium-energy accelerator complexwith roughly 350 national and inter-national users. With a maximum pro-ton energy of about 2.8 GeV (~3.62GeV/c) COSY allows the productionof (strange) mesons up to the φ (1020).The accelerator complex comprisesthree major hadron-physics detectorsystems (ANKE, TOF, and WASA),as well as smaller experiments, which

are mainly run by external groups(pdEDM). In addition, preparativestudies for producing intense beamsof polarized antiprotons are carriedout (PAX).

In the upcoming decade, hadronphysics will undergo a transition fromlight quark systems to hadrons withcharm quarks, which will be pursuedat the Facility of Antiproton and IonResearch FAIR (GSI Darmstadt). IKPis the leading institution of the con-sortium that designs and constructs ofHigh-Energy Storage Ring (HESR)for antiprotons at FAIR. Also compo-nents of the PANDA experiment aredeveloped and preparations for thePAX experiment proceed with astrong contribution of IKP.

COSY is a unique spin physicsfacility with hadronic probes and assuch it is the ideal basis for searchesfor electric dipole moments (EDM) oflight ions in storage rings.

The IKP is also involved in thedevelopment of novel acceleratortechnologies and concepts. For exam-ple, a 2 MV electron cooler will beinstalled in COSY and research onlaser-driven particle acceleration isbeing performed.

Theory Activities—The Physics Case

Although very well tested at highenergies, QCD, the theory of stronginteractions, poses a great challengeto theory and experiment at low and atintermediate energies. Of paramountinterest are the mechanism underlyingquark and gluon confinement andspontaneous chiral symmetry break-ing. The low energy regime, whereFigure 1. Inside the COSY accelerator hall.

laboratory portrait


only the lightest three quarks (up,down, strange) play a role, is largelycontrolled by the mechanism of spon-taneous chiral symmetry breaking—the quark mass terms play a relativelylittle, but relevant role, while at higherenergies, where also the charm andeventually the bottom quarks appearas dynamical degree of freedom, thequark mass terms has much moreinfluence on hadronic properties. Asystematic, consistent study of bothregimes is the precondition for adeeper understanding of QCD in thenon-perturbative regime.

The theoretical tools at our dis-posal are effective field theories (suchas chiral perturbation theory for thelight quark sector) and lattice gaugetheory. While the former work withhadronic degrees of freedom, the lat-ter numerically solves discretizedQCD directly using quarks and glu-ons. Another promising route is theuse of lattice techniques with had-ronic degrees of freedom for nuclearstructure studies—this allows one tosolve the nuclear many-body prob-lem without further approximations.On the one hand lattice studies allow

one to solve the problems at handexactly, the numerical effort is veryinvolved and requires the use ofsupercomputers as they are availableon campus in Jülich. On the otherhand, effective field theories are tech-nically easier to deal with, but requirean increasing number of couplingconstants when making the calcula-tions more accurate. An importantstrategy is to use the lattice to deter-mine theses constants that then allowone to make predictions for manyother observables based on the prop-erly tailored effective field theory. Inaddition what is needed are high accu-racy experiments to test the predic-tions. Those are provided by modernexperiments like those at COSY, to bedescribed below, BES-III in China,Belle in Japan, KLOE in Italy, ELSAand MAMI in Germany, Jlab in theUSA, LHC in Switzerland, and in thefuture from the accelerator complexFAIR.

The activities of the theory groupat the IKP comprise hadron andnuclear physics. Current projects arethe development of an effective fieldtheory for nuclei and hyper-nuclei

using both standard many body toolsas well as lattice techniques, a system-atic investigation of hadronic mole-cules involving all types of quarkflavors—of direct relevance forCOSY and FAIR—and a study of theimplications of the quark masses onhadronic observables. For example,the quark mass induced piece of theproton-neutron mass difference wasextracted from the experimental dataon the forward-backward asymmetryin pn → dπ0, the accuracy of thisextraction will be further improved,once data on dd → απ0 will be avail-able from COSY. Further, a proposalwas developed to extract the lightquark mass ratio from certain botto-monia transitions—here the mea-surements could be performed withthe LHCb detector at the LHC. Thisgrew out of a systematic study ofcharmed meson loop effects in char-monium transitions that have led to acornucopia of predictions to be testedwith BES-III and PANDA. The the-ory group is also engaged in latticeQCD studies. For example there iscurrently a project under way toextract for the first time the width ofa baryon resonance, that is, the widthof the Δ(1232), using the local Blue/Gene high performance computer.This will provide a highly non-trivialtest of QCD in the non-perturbativeregime.

COSY Accelerator Complex The COSY cooler synchrotron and

storage ring (Figure 1) provides polar-ized and unpolarized proton (deu-teron) beams in the momentum rangefrom 300 (600) MeV/c to 3.7 GeV/cfor internal and external target experi-ments. The COSY accelerator com-plex includes H– and D– sources andthe cyclotron JULIC for pre-acceler-ation. The negative charged ions are

Figure 2. Layout of the new 2 MV electron cooler for COSY.

laboratory portrait


injected via charge exchange into theCOSY ring. COSY has a racetrackdesign, consisting of two 180° arcsections connected by 40 m straightsections. The total length of the ring is184 m.

To prepare high-precision beamsfor internal and external experimentstwo different beam cooling tech-niques are utilized: electron cooling toincrease phase-space density at injec-tion energy by means of stackinginjection in combination with trans-verse feedback, and stochastic coolingto counteract beam heating of storedions due to interaction with internaltargets. Stochastic cooling covers themomentum range from 1.5 GeV/c upto the maximum COSY momentum.

A new 2 MV electron cooler(Figure 2) for beam cooling up tomaximum COSY momentum is beingdeveloped in cooperation with theBudker Institute in Novosibirsk andwill be installed at COSY in 2011.The preparation of high-precisionbeams with increased luminositiesabove 1032 cm–2 s–1, using high-density internal targets, is the mainapplications for high-energy coolingat COSY. Technical developments forthis electron cooler are also importantsteps toward the proposed 4.5(8) MVelectron cooler of the HESR. TheHESR electron cooler layout willstrongly benefit from the experiencesof the electron cooler operation atCOSY.

Polarized beams are essential forthe physics program at COSY. To keepthe polarization during accelerationtwo different types of first-order spinresonances have to be overcome,namely imperfection resonancescaused by magnetic field errors andmisalignments of the magnets, andintrinsic resonances excited byhorizontal fields due to the vertical

focusing. For protons, in the energyrange of COSY, five imperfection res-onances have to be crossed. Verticalcorrection dipoles or a partial snakecan be used to preserve polarization forthis type of spin resonances by excitingadiabatic spin flips. To preserve thepolarization at the intrinsic resonances,a fast change of the vertical betatrontune and therefore a fast crossing of theresonance is applied. For polarizeddeuterons no resonances are encoun-tered in the energy range of COSY forregular vertical betatron tunes.

The main diagnostic tool to mea-sure polarization of the internalCOSY beam is the EDDA detector,primarily designed and used to mea-sure the pp-scattering excitation func-tion during synchrotron acceleration.

Experiments at COSY

Experimental Facilities ANKE (Apparatus for studies of

Nucleon and Kaon Ejectiles), is alarge acceptance forward magnetic

spectrometer (Figure 3) at an internaltarget station in the COSY ring.ANKE consists of three dipole mag-nets, acting as a chicane for the circu-lating COSY beam. The central dipoleis movable to adjust the momentum ofthe detected particles independent ofthe beam momentum. ANKE isequipped with dedicated detectors forcharged kaons that allow the identifi-cation of certain K+K– final states in amore than 10 orders larger back-ground. This capability has beenrecently exploited for a high-precisionexperiment on φ (1020)-meson pro-duction in nuclei. Using deuteriumcluster targets, reactions on the neu-tron are tagged by detecting the lowenergy recoil “spectator” proton in asilicon tracking telescope in vacuumnext to the target. A polarized internaltarget system comprising an atomicbeam source, a Lamb-shift polarime-ter, and a storage cell is in use atANKE since 2005.

TOF (Time-Of-Flight), is a non-magnetic spectrometer (Figure 4)

Figure 3. The ANKE forward spectrometer.

laboratory portrait


located at an external COSY beam-line, combining excellent trackingcapability with large acceptance andfull azimuthal symmetry allowing tomeasure complete Dalitz plots. TOFis optimized for final states withstrangeness. The strength of this high-acceptance spectrometer is the capa-bility of delayed secondary displacedvertex detection, for example, fromhyperon Λ, Σ+, . . . decay products viaa silicon micro-strip detector placedclose to the interaction region. Withthe new straw tube tracking systemrecently commissioned, TOF has asignificantly improved mass resolu-tion and reconstruction efficiency.

WASA (Wide Angle ShowerApparatus), an internal 4π spectrome-ter (Figure 5) with large solid angleacceptance, is operated in the internalCOSY beam. WASA comprises an

electromagnetic calorimeter, a verythin superconducting solenoid, highgranularity central and forward track-ing detectors for reconstruction ofcharged and neutral decay particlesand for angular and differentialenergy measurement. The target pro-tons and deuterons are delivered bymeans of a unique frozen-pellet targetsystem providing hydrogen or deute-rium spheres with diameters of ~25μm. The pellet target system providesa high density target with high puritynecessary to measure rare mesondecay processes at high luminosity.The close to 4π geometrical accep-tance of WASA allows for an effi-cient search for rare final states. Themeasurement of exclusive final statesrepresents the physics focus for theinvestigation of violation and break-ing of basic symmetries. With the

operation of WASA-at-COSY, high-statistics studies aiming at rare decaysof π, η, ω, and η’ are effectively turn-ing COSY into a meson factory.

Recently a new internal target sta-tion has been set up for PAX (PolarizedAntiproton eXperiments), which aimsat providing an intense beam of polar-ized (anti-)protons by spin-filtering.The plan is to test and commission allequipment with protons at COSYbefore moving to CERN/AD for mea-surements with antiprotons.

In addition to providing beams forexperiments with these detector sys-tems, COSY is used for:

• Research and development of ded-icated components, which are sub-stantial for a successful operationof the HESR. In beam dynamicsexperiments at COSY their prop-erties can be examined under simi-lar conditions as at the HESR.Specifically, an improvement ofthe recently developed high sensi-tivity pickup and kicker structuresin the frequency range 2 to 6 GHzfor the HESR stochastic coolingsystem will be carried out. Theircharacteristics can be well investi-gated with a COSY beam. A noveldesign and construction of highfrequency pickup and kicker struc-tures for the collector ring CR atthe FAIR facility will be per-formed. The structures will betested with beam at COSY.

• Preparatory studies (polarimetry,beam lifetime, and spin coherencetime measurements) for (p and d)EDM searches at storage rings. Insuch measurements, the EDDAdetector is used as a polarimeter.

• Tests of detector components andprototypes of the future largeFAIR detector systems like CBMand PANDA.

Figure 4. The COSY-TOF experiment.

laboratory portrait


COSY is unique on a worldwidescale in its possibility to store, acceler-ate, and manipulate polarized protonand deuteron beams and to use it forinternal and external experiments. Themajor scientific issues for the ongoinghadron physics experiments are:

• Investigation of symmetries andsymmetry violations, for examplein rare meson decays;

• Hadron reactions, like NN interac-tions, in particular the np systemand the di-proton (pp)s final state,YN-interactions (spin-resolved ΛNscattering lengths), and meson-nucleus interactions (e.g., (quasi-)bound states);

• Hadron structure and spectros-copy, like the investigation of N*resonances, in particular of thosecoupling to strangeness.

Selected Experimental Results from COSY (WASA and PAX)

Since the “standard” strong andelectromagnetic decays are stronglysuppressed for the η (and η’) meson,the η provides a perfect laboratory tosearch for decays that are forbidden byfundamental symmetries. At WASA-at-COSY the two complementary reac-tions pp→ppη and pd→3Heη have

been investigated for hadronic η pro-duction. They differ considerably inproduction cross section, however alsoin the contribution of multi-pion back-ground, which is roughly 20 timeslarger for the ratio σ(2π0)/σ(η) in thepp reactions and during the last twoyears, data sets from pp and pd interac-tions have been collected. The decayη→ 3π0 forbidden by isospin conser-vation has been studied following thereaction pp→ppη and the extracteddata with more than 8·105 eventsη→3π0 result in a slope parameter α= –0.027 ± 0.008(stat) ± 0.005(syst)(Phys. Lett. B 677:24–29 (2009)) ofthe efficiency corrected radial den-sity distribution of the Dalitz plotthat compares well with results fromother installations (CBall MAMI,Celsius/WASA, KLOE, CBall BNL).The measurement of the slopeparameter allows for a sensitive testof QCD predictions, and the experi-mental findings show a strong dis-crepancy to the central value ofcurrent chiral perturbation-theorycalculations (up to NNLO), wherethe large uncertainty, however, doesnot allow to decide the sign of theslope.

η decays were studied using thepd→3Heη reaction at a beam energy

of 1 GeV. An unbiased data sample of1.1·107 η meson decays was col-lected. Results to be published includethe search for the box anomaly contri-bution in the decay η→π+π−γ (Ph.D.thesis C.F. Redmer, http://www.fz-juelich.de/ikp/wasa/theses.shtml). Thedecay η→π+π−γ was studied with thegoal to test chiral QCD anomaliesdescribed by the Wess-Zumino-Witten (WZW) Lagrangian and tosearch for flavor conserving CP viola-tion. To test the validity of the differ-ent models, not only the decay ratebut also differential distributions ofthe Dalitz plot variables are comparedwith experimental data. As shown inFigure 6, the measured photon energyspectrum was found at variance withthe simplest gauge invariant matrixelement of η→π+π−γ, but can bedescribed by a Vector Meson Domi-nance ansatz. The pion angular distri-bution is consistent with a relative p-wave of the two-pion system. With13740 ± 140 events these data repre-sent the currently largest sample of anexclusive measurement. Up to nowthe pd data sample was increased to3·107 η meson decays. Further resultsinclude symmetry-breaking decays(η→π+π−e+e−, η→π0 e+e−), tests ofchiral perturbation theory (η→3π,

Figure 5. Fish-eye view of the WASA-at-COSY experiment.

laboratory portrait


η→π0 γγ), and single and doubleelectromagnetic transition form fac-tors with the most ambitious goalbeing the search for new physics withthe η→e+e− decay.

Due to 10–20 times larger produc-tion cross section (10 μb at 1.4 GeV)further progress toward rare η decaysis being made by focusing on thepp→ppη reaction. Meanwhile, tag-ging on the pp→ppη reaction poses achallenge. A first investigation con-siders production reactions of ηmesons as well as multi pion chan-nels; see “Double-Pion Production inProton-Proton Interactions” (Ph.D.thesis T. Tolba, http://www.fz-juelich.de/ikp/wasa/theses.shtml). The firstlong production run of 8 weeks forη meson decays in pp interactionswas recently carried out. The dataare presently being analyzed. Theextension of the physics program to ωand η′decay studies is anticipated inbeam times scheduled for late 2010and spring 2011.

On the road to the goal of the PAXcollaboration to produce a polarizedantiproton beam lie major technicalchallenges. Theoretical calculationsfound in literature predicted a verylarge low-energy lepton-hadron spinflip cross section and it was suggestedthat a viable method for producingpolarized antiproton beams would beto use a co-moving lepton beam inconjunction with a stored hadronbeam at small relative energy. How-ever, in a recent COSY experimentthe PAX collaboration showed thatthe spin-flip cross section was grosslyoverestimated, see Figure 7 and Phys.Lett. B6 74:269–275 (2009).

Thus the PAX collaboration willfocus on the technique of spin-filteringas means to obtain a stored polarizedantiproton beam. This method hasbeen proven to work in an earliermeasurement at the TSR ring inHeidelberg and a COSY experimentto determine the energy dependenceof the process is being installed. Later

it is planned to move the experimentto the AD ring at CERN where anti-protons are injected and decelerated.

Preparations for the HESR Antiproton Ring

The HESR is an essential part of theantiproton physics program at theFAIR project. It will provide antipro-tons in the momentum range from 1.5to 15 GeV/c for the internal targetexperiment PANDA. A consortiumconsisting of FZ Jülich, GSI Darmstadt,HIM (Helmholtz-Institute Mainz),University of Bonn, and ICPE-CABucharest is in charge of HESR designand construction.

Powerful phase-space cooling isneeded to reach demanding experi-mental requirements in terms of lumi-nosity and beam quality. Therefore, abroadband stochastic cooling systemin the range from 2 to 4 GHz (with anupgrade option for longitudinal cool-ing to 4–6 GHz above 3.8 GeV/c) isdeveloped. Due to the modularizedconstruction concept of FAIR, theplanned 4.5 MV electron cooling sys-tem is postponed to a later stage.

Various beam dynamics studieshave been performed to guarantee therequired equilibrium beam parame-ters, beam lifetime, and beam stabil-ity. Comprehensive beam dynamicsexperiments have been carried out totest the developed momentum coolingmodels. The interaction of the anti-proton beam with an internal targetand the fields of a barrier bucketcavity are included.

Magnet design of dipole, quadru-pole, sextupole, and correction dipolemagnets has been finalized. Three-dimensional field calculations havebeen performed to minimize the multi-pole components of the various magnettypes. After negotiations with tenders

Figure 6. Data for the h→p+p-g reaction. Background subtracted and efficiencycorrected angular distribution of the pions (left) and the photon energydistribution (right). The shaded areas represent a 1- s band corresponding tothe systematic uncertainties. The angular distribution is compared with arelative p-wave (dashed curve) of the pions. Contributions of higher orderpartial waves are negligible. The line shape of the photon energy distribution isconfronted with predictions of the simplest gauge invariant matrix element(dot-dashed curve), and a VMD-based calculation (solid curve).

laboratory portrait


the magnet production is going to bestarted with a pre-series. A detailedconcept for the vacuum system of theHESR has been worked out. Two testdevices are manufactured. The firstdevice to test the mechanical stabilityof the favored clamping flanges underultra-high vacuum conditions isalready operated. The second test facil-ity will be a genuine cut-out of the arcfrom one center of a dipole to the nextneighbored one.

Studies of beam behavior withpellet target, barrier bucket, and sto-chastic cooling have been performedat the cooler synchrotron COSY tobenchmark simulation codes and testaccelerator components for HESR.The mean energy loss induced by theinteraction of a circulating beam withan internal pellet target cannot becompensated by phase-space coolingalone. To compensate the meanenergy loss and thus to provide anantiproton beam with a significantlyreduced momentum spread, a broad-band barrier bucket cavity will be usedin the HESR. Design, production, andassembly of such a cavity have beenfinalized and it is routinely operated inCOSY (Figure 8, left). In order toavoid initial particles losses the beamcan be pre-cooled by time-of-flightcooling. It has experimentally beenconfirmed that this cooling methodhas a larger cooling acceptance com-pared to usual filter cooling. Newhigh-sensitivity pickups for stochasticcooling have been designed and builtfor the HESR (Figure 8, right). Theyhave been successfully tested withCOSY beam and have been proventheir predicted performance.

Preparations for the PANDA Experiment

The PANDA experiment at thehigh energy storage ring (HESR) will

perform high precision investigationsof antiproton annihilation on protonand heavier ion fixed targets in orderto pursue various topics around theweak and strong forces, exotic statesof matter and the structure of hadrons.In order to serve the wide physicspotential with antiprotons at HESR,PANDA is designed as a general pur-pose detector covering nearly thecomplete solid angle for both neutraland charged particles with goodmomentum and particle identification(PID) resolution as well as excellentvertex determination. IKP has takenover a key role in the preparation ofthe physics program, as well as focus-ing its instrumental activities on theinteraction region and the surroundinginner detectors for charged particletracking.

Together with partners fromMoscow, IKP is developing animproved pellet target system. Thissystem has about an order of magni-tude less divergence of the pelletstream, thereby allowing a finer focusof the HESR beam as well as lowerexpected fluctuations of the luminos-ity as compared to the WASA pellettarget currently installed at COSY.

The first detector outside of theinteraction region will be a siliconpixel/strip Micro Vertex Detector(MVD) that will reconstruct (second-ary) vertices with a precision below50 micron. This device will enableevents with the production of opencharm to be tagged. Here IKP hastaken over major aspects in the over-all mechanical design and the devel-opment of the data transport systems.Detailed simulations of the radiationdose and expected spatial resolutionhave been performed, together withthe development of the necessarysoftware development for the datahandling and reconstruction.

A Central Tracker (CT) will sur-round the MVD. At IKP a concept forthe CT based on straw tube propor-tional chambers has been developedtogether with groups in LNF (Fras-cati, Italy) and Pavia (Italy). Thedesign is based on the hardware of thestraw tube tracker now in operation atthe COSY-TOF experiment (Figure 9).Currently a full scale prototype isbeing assembled and new readoutelectronics are being developed toenable PID via specific energy loss inthe active gas volume.

In order to achieve the optimalmass and width precision from reso-nance and threshold scans, the inte-grated luminosity must be determinedwith high precision. Therefore IKP haspresented a concept for a luminosity

Figure 7. Posterior probabilityfunction p for the two spin-flip cross-sections s(S, ^) and s(S, �) at arelative electron-proton velocity of V= 0.002 c. The two lines indicate the90% and 99% confidence levels. Theexperiment fails to find an effect andthe upper limit for the cross-section isin the order of 107 b. The rather lowfree electron target density is themajor limitation for the cross-sectiondetermination. As a setup forproducing a polarized antiprotonbeam suffers the same problem, thisprocess does not provide a suitablemethod.

laboratory portrait


monitor based on measuring elasticscattering in the Coulomb-stronginteraction interference region. Thissystem is based on tracking the anti-protons scattered near the beam axiswith multiple layers of silicon stripdetectors.

Search for an Electric Dipole Moment (EDM) of Protons and Deuterons

Searches for EDM are a forefrontresearch issue, because finding a non-zero EDM would be a major discov-ery pointing to physics beyond theStandard Model of elementary parti-cle physics. Impressive upper limits(neutron equivalent in the order of10−26 e·cm) have been obtained inrecent years. These are further pushedby upgrading existing experiments onelectrons and muons, heavy atoms andmolecules, and in particular also theneutron, and by designing new ones.

The IKP is planning to search forEDM in a storage ring with a statisti-cal sensitivity of few 10−29 e·cm peryear, pushing the limits even furtherand with the potential of an actual par-ticle-EDM discovery. For such studiesa completely new approach has

recently been proposed for protons,deuterons and possibly also 3He,which will rely on the time develop-ment of a horizontal spin componentof these particles in a new class ofstorage rings. In the course of this, ithas become obvious, that COSY—with its polarized beams, including thenew hardware (like a low-β sectionand a Siberian snake) and the targetand detector systems—is very close tobeing a test-bench for polarimetry,spin coherence time investigations,and so on.

An R&D program at the COSYstorage ring within an internationalcollaboration (EDM@COSY) alreadyproved the required sensitive and effi-ciency of deuteron polarimetry. All ofthe information gleaned during thesestudies will be incorporated into adesign for a prototype polarimeterthat will be tested on the COSY ring.The next step will be the investigationand optimization of spin coherencetime in COSY. The natural spincoherence time of horizontal polariza-tion needs to be determined andextended by bunching the beam andimprovements to the ring lattice bymeans of high-order field corrections.

Intense R&D work has also to beperformed before the design of thefinal EDM ring can be started. Mainobjectives are the development ofhigh-sensitivity beam positioningmonitors and combined electrostatic/magnetic field deflectors with cutting-edge field quality. The coil and con-ductor plate configuration has to beoptimized with respect to field qualityand stability and a prototype deflectorto be build and tested to ensure itsperformance.

Laser-Particle Acceleration The physics of laser-plasma inter-

actions has undergone dramaticimprovements in recent years. Bydirecting a multi-TW, ultra-short laserpulse onto a thin foil or a gas, it isnow possible to produce high-energyproton, ion, and electron beams. It isa yet untouched issue whether thelaser-generated beams are or can bespin-polarized and, thus, whetherlaser-based polarized sources areconceivable. One may either think ofa spatial separation of certain spinstates by the huge magnetic field gra-dients that are inherently generatedin the laser-generated plasmas, or ofpre-polarized target particles that

Figure 8. Barrier bucket cavity installed in the COSY ring (left) and octagonalslot-coupler for stochastic beam cooling in HESR (right).

Figure 9. Prototypes of straw detectorsfor the PANDA experiment.

laboratory portrait


maintain their polarization during therapid acceleration procedure.

Making use of its experience inpolarized beams and targets as well asin building fast on-line detectors, IKPhas established a working group that iscarrying out exploratory studies aimingat the realization of a laser-basedsource for (un-)polarized beams in theCOSY-injection energy regime. Thiswork is carried out at the 300 TW Ti:Salaser facility Arcturus at DüsseldorfUniversity where currently proton ener-gies of up to 10 MeV are achieved.

The preparation of acceleratorcomponents, comprising a set of dipoleand quadrupole magnets, for beamcatching has begun at the IKP. Such atrimmed, stable beam could later beinjected into a conventional acceleratorlike COSY, provided that its injectionenergy of 40 MeV is reached.

Up to now the beams exhibitbroad energy and angular distribu-tions. It is known that via specialtarget engineering quasi mono-ener-getic protons can be generated due tothe spatial reduction of the accelerat-ing field. Improved coupling effi-ciency and thus maximum protonenergies can be achieved by usinglimited-mass targets, like small liq-uid drops or pellets. Such frozen pel-let targets are currently being used forCOSY experiments and seem to be apromising tool also for the effectivegeneration of laser-generated particlebeams.

Summary COSY in combination with its

complementary experimental facili-ties and polarized hadronic beams andtargets provide unique opportunities

to investigate a broad physicsprogram holding the potential tosignificantly contribute to our under-standing of hadron physics in thelight quark sector. Experiments on thestructure and interaction of baryonsand mesons will continue at ANKEand COSY-TOF. This comprises thequantitative analysis of the observedbaryon states and the polarizationdegrees of freedom as well as neutroninteractions using deuteron beams ortargets and spectator detection. Withthe WASA-at-COSY, a detector hasbecome available that allows high-statistics studies aiming at very raredecays of η and η’ regarding funda-mental questions such as symme-tries and symmetry violation withinand outside the standard model. Aparticular strength is the close col-laboration between experiment andthe theory groups at IKP and otherinstitutions.

COSY users, together with theIKP, will play a crucial role in the

design, construction, and exploitationof the HESR and PANDA at FAIR(GSI Darmstadt). COSY plays a deci-sive role in the education of futurehadron physicists in ongoing experi-ments. This will also enable them toprepare for and make optimum use ofthe future opportunities offered byFAIR. For further and comprehensivedetails on the current COSY physicsprogram refer to Ref. [1].

Reference 1. IKP Annual Report 2009, Berichte des

Forschungszentrums Jülich 4316, ISSN0944-2952; http://www.fz-juelich.de/ikp/publications/AR2009/de/contents.shtml

MARKUS BÜSCHER

ANDREAS LEHRACH

FRANK GOLDENBAUM

Institut für Kernphysik andJülich Center for Hadron Physics,Forschungszentrum Jülich, Jülich,

Germany

Markus Büscher, Andreas Lehrach and Frank Goldenbaum (from left) inthe COSY accelerator hall.

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Long Range Structure of the Nucleon*

MARC VANDERHAEGHEN AND THOMAS WALCHER Institut fur Kernphysik, Johannes-Gutenberg-Universitat Mainz, Mainz, Germany

Introduction: Ranges Many physicists have the following picture of the struc-

ture of the nucleon: In the inner region at “short range”reside quarks bound by gluons, in the outer region at “largedistances” live mesons and in particular pions. The nucleonconsists of constituents (i.e., “constituent quarks” andpions), as the atom consists of a nucleus and electrons, andthe nucleus of protons and neutrons. The range of the inner“colored” region, frequently called “confinement radius,”is rather elusive. It is a model parameter in the old bagmodel or models for the nucleon resonances based on theconstituent quarks. One can estimate it from experiment byidentifying it with the “annihilation radius” of the antiproton–proton system. Only quark–antiquark annihilation in theoverlap region of color can contribute to annihilation [2]. Itamounts to approximately 0.8 fm, in reasonable agreementwith the mentioned model parameters. However, it cannotbe easily identified with the root-mean-square (rms) radiusof the electric charge of the proton, since the pion cloudwill contribute to the charge distribution. A rough idea ofthe range of this contribution may be gotten by the Comp-ton wave length of the pion which is of the order of 1.4 fm.

However, this picture fails in two ways. Firstly, thenucleon moves after the scattering in most experiments atrelativistic velocities and therefore its structure looks dif-ferent in different reference frames. The simplest exampleis the transformation of the magnetic moment into an elec-tric dipole moment. This situation makes it particularly dif-ficult to compare experiments to model calculations basedon rest frame wave functions. These wave functions haveto be “boosted” to the correct momentum transfer and thereis no consistent way of doing that. Secondly, at relativisticenergies particle-antiparticle (i.e., quark–antiquark), pairshave unavoidably to be considered making the picturemuch more involved.

These two aspects will be discussed in the third section. The relativity destroys the simple picture also in

another way. We usually relate ranges with momentumtransfer via Heisenberg’s uncertainty relation. However,

since in relativistic mechanics space and time are inti-mately connected no relativistic uncertainty relation exists[3]. Therefore the assignment of ranges to quantitiesdepending on the negative four momentum transfersquared Q2 = − q2, as for example, in some plots of the run-ning coupling constant, is rather misleading. We shall,therefore, in this article distinguish between the non-relativistic picture derived at small momentum transfersand the relativistic case where we have to use the relativis-tic quantum field theoretic description. At small momen-tum transfers we can approximate the four momentumtransfer q with the three momentum transfer ≈ − q2 andmaintain the familiar interpretation of form factors (nextsection). In the third section we shall show how we canconnect the non-relativistic picture to the underlyingquark–gluon structure. We shall see that new experimentsin just the relativistic domain are needed in order to clarifyhow nucleons are made up of quarks and gluons or, moreprecisely, how hadrons emerge from QCD.

q→2

*This is an abridged version of Ref. [1].

0.94

0.95

0.96

0.97

0.98

0.99

1

1.01

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

GE

p/G

D

Q2 [(GeV/c)2]

Spline fitstat. errorsexp. syst. errorstheo. syst. errors

Simon et al.Price et al.Berger et al.Hanson et al.Borkowski et al.Janssens et al.Murphy et al.

Figure 1. The electric FF of the proton GEp/GD obtainedfrom a direct fit to the cross sections with the spline modelto data measured with the 3-Spectrometer set-up at MAMI.The FF is normalized to the dipole form given in the text.The 1 s-error band is shown for the indicated errors.

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Nonrelativistic Interpretation of Nucleon Form Factors We begin with form factors of the nucleons and

summarize what we know up to 2009 (see, e.g., Refs. [5–7]for some recent reviews on nucleon form factors). The pre-2000 data suggest that the magnetic and electric form fac-tor of the proton follow a universal form, the “dipole form”

GD(Q2 ) = 1/(1+Q2/Λ2D)2, with the scale parameter ΛD = 0.843

GeV approximately equal to the mass mr of the r meson.

The case was closed and considered to be textbook mate-rial. This finding was the basis for the much discussed“vector dominance model” in strong interactions. (For arecent discussion see Ref. [8].) The r meson mass defines a“small range” of an exponential distribution, somewhatunphysical due to its discontinuity at r = 0. It was believedthat the dipole form would also describe the long rangescharacterized by the rms radius of the proton. A measure-ment at the High Energy Physics Laboratory HEPL at

Stanford gave [9]. Today

the CODATA06 value 0.8768(69) fm is based mostly onmeasurements of electronic atoms [10]. This value is con-firmed by a recent high precision determination at theMainz Microtron (MAMI) yielding [4]:

As discussed in Ref. [11] this value is significantly largerthan the largest value derived from dispersion relations[12] and is unexplained in most nucleon models. On theother hand, a recent study of the Lamb shift in muonichydrogen at the Paul-Scherer Institute (PSI) in Zuerichyielded a very precise value as low as 0.84184(67) fm [13]in agreement with the upper bound of the dispersion-relations calculations [12]. Taken the CODATA06 valuetogether with the new determination from electron scatter-ing the combined mean value changes hardly, but, thedeviation has now a significance of 7 standard deviations.Since the theoretical description of the Lamb shift inmuonic hydrogen is rather matured the explanation of thedifference is a puzzle so far.

Considering the focus on “long ranges” the questionarises how much of the rms radius is possibly due to a pioncloud. There were weak indications that the pion cloudcould be directly seen in the FFs in a similar way as the shellstructure of the nucleus. This indication came from a coher-ent analysis of the data available until 2003 for the electricand magnetic FFs of the proton and neutron [14]. Since 2003

the data base has improved so much that we want to basethis discussion on the most recent measurements.

Figure 1 shows the electric FF of the proton as derivedfrom a direct fit of a FF model to data obtained with the3-Spectrometer set-up at MAMI. This method takes advan-tage of modern computers and fits the theoretical cross sec-tion (Rosenbluth formula) to a large set of angulardistributions measured at six energies 180, 315, 450, 585,720, and 855 MeV. All together about 1,400 settings weremeasured. In this way the “measurement at constant Q2”(i.e., the old Rosenbluth separation), becomes obsolete anda very broad kinematic range can be covered indeed. Apoint of concern may be the analytical model used for theelectric form factor GEp and magnetic form factor GMp in thedirect FF fits. Here about a dozen different forms have beenused, all yielding essentially the same results [4]. The rmsradius is, however, somewhat dependent on them and thesecond systematic error in Eq. (1) reflects this dependence.

It is evident that these form factors show some structureafter the gross dependence, assumed to be given by thestandard dipole form, has been divided out. In Figure 1 oneobserves two slopes for GE/GD. The steep negative slope atsmall Q2 is reflected in the large rms radius discussed ear-lier. The reverse is true in Figure 2 for the rms radius ofGM/(mpGD). A shoulder structure is indicated in both FFs atQ2 ≈ 0.15 GeV2. It is shifted compared to the bump struc-ture derived by Friedrich and Walcher [14] from the pre-2003 data and cannot be identified with it. However, justconsidering the scale of the rms radius and the scale of the

r m2 = 0.805(11) 12fm ≈ / r

rE2

. .= 0.879(5) (4) (2) (4)stat syst model group fm (1)

0.95

0.96

0.97

0.98

0.99

1

1.01

1.02

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

GM

p/(μ

pGD

)

Q2 [(GeV/c)2]

Spline fitstat. errorsexp. syst. errorstheo. syst. errors

Price et al.Berger et al.Hanson et al.Borkowski et al.Janssens et al.

Figure 2. As Figure 1 for the magnetic FF GMp/(μpGD) ofthe proton.

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structure it is suggestive to look for pion cloud contribu-tions in the modeling of the nucleon.

Since the bulk charge of the proton resides at “smallranges” and extends out to the range of the pion cloud, theseparation of the inner component from the pion cloudcontribution will be somewhat arbitrary. Here the neutronwith a total zero bulk charge promises an experimentalaccess since one way the neutron could acquire a chargedistribution is just by its virtual dissociation n → p + π−.This means that the pion cloud should be more clearly visi-ble again as a signal at large radii r ≈ λCompton = 1/mπ ≈ 1.4 fmin the neutron charge distribution.

One could be tempted to look at the neutron rms radiusas in the case of the proton in first place. However, thementioned recoil effect causes the magnetic moment tocontribute to the small electric form factor. It turns out thatthe electric rms radius of the neutron is a subtle interplaybetween the recoil effect and the charge radius proper. Asummary can be found in Ref. [11].

Figure 3 shows a compilation of all data including theresults from the MIT Bates measurement with the BLASTdetector at the South Hall Ring at small Q2 [16] and themeasurement at the Jefferson Laboratory (JLab) by the HallA Collaboration at large Q2 [17]. All these measurements

use the dependence of the cross sections of polarised targets orrecoil polarisations of the ejected nucleons for polarized elec-trons on the FFs. The curve shows a fit of the phenomenologi-cal model of Friedrich and Walcher (FW) [14].

As already mentioned, the phenomenological FWmodel tried a coherent fit of a smooth bulk curve with asuperimposed bump for the pion cloud. This fit of thebefore 2003 data showed indeed a 2s contribution abovethe smooth curve causing a shift of the negative charge toradii around 1.5 fm. The inclusion of the MIT [16] andJLab data [17] in the fit makes the bump disappear. Atsmall Q2 the neutron FFs cannot be reliably determineddue to the model dependence of the extraction of the formfactor from the scattering of the polarized electrons fromunavoidably bound neutrons in deuterium of 3He targets.Only new, even more precise measurements will be able toimprove the situation. However, it will be mandatory tofurther study the reaction mechanism experimentally inorder to check the theoretical corrections.

The scope of this article is on “long range structure,”meaning that one wants to discuss the idea of the spatialdistribution of the constituents of the nucleon. In the restframe the three-dimensional charge distribution of a spher-ically symmetric non-relativistic system is obtained as:

where ~r(k) is an intrinsic FF. As already pointed out therelativistic effects do not allow for a simple interpretationof the electric and magnetic FFs in terms of charge andmagnetic density distributions in the rest frame system.However, there is a special reference system, the Breit orbrick-wall system, defined by having no energy transfer nto the nucleon, in which the charge operator for a non-relativistic (static) system is only expressed through theelectric FF GE. In this system the four-momentum transfersquared becomes . However, the restframe systems (laboratory systems) for different q2 movewith different velocities with respect to the Breit system.For a relativistic system, to relate its intrinsic FF ~r(k) anddensity to the Breit frame in which the system of mass Mmoves with velocity , requires a Lorentzboost relating k2 = Q2/(1 + t). This relation shows that forQ2 → ∞, there is a limiting largest intrinsic wave vectork → 2M = 2p/λlim. In this picture, no information can beobtained on distance scales smaller than this wavelengthdue to relativistic position fluctuations (known as the

rp

r3 2

20

0( ) =

2( ) ( ),

dr

dkk j rk k�

+∞

∫ (2)

q q q2 2 2= − = −→ →n 2

u = t/(1+ t)

Figure 3. A compilation of the recent data for the neutronelectric FF, GEn, obtained at NIKHEF (triangle), Bates MIT

(stars), JLab (squares), and MAMI Mainz (circles), with the

quasi free →e p → p®me and the reactions. Thecurves correspond with a new fit of a phenomenologicalmodel (solid red curve) [14], and of a Generalized PartonDistribution parametrization (dotted black curve) [15].

e He ppne→ →

→3

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Zitterbewegung). For a non-relativistic system as for exam-ple, 16O λlim is below 0.04 fm, whereas for the nucleon, itcorresponds with λlim � 0.66 fm. Extracting the density fora relativistic system as the nucleon, therefore requires aprescription in order to relate the intrinsic FFs ~r(k) in Eq.(2) to the experimentally measured FFs (see Ref. [18]). Tosee the transitional region from the distance scales whererelativistic position fluctuations hamper our extraction ofrest frame densities to distances where the concepts of anon-relativistic many-body system can be approximatelyapplied, we visualize the charge density in Figure 4. Itdepicts the Fourier transform Eq. (2) using the fit in Figure 3(solid red curve). One notices a negative charge density atdistances around and larger than 1 fm. With all caveats wemay interpret the negative charge as a “pion cloud” in thenonrelativistic limit since it extends beyond the confine-ment radius of about 0.8 fm.

Relativistic Picture We now turn to the relativistic picture and see how it does

complicate matters, however, for the benefit of a deeperinsight. As already mentioned both, the size and the shape ofan object, are not relativistically invariant quantities: observ-ers in different frames will infer different magnitudes forthese quantities. Furthermore when special relativity is writ-ten in a covariant formulation, the density appears as the timecomponent (zero component) of a four-current density Jμ =(r, J) (in units in which the speed of light c = 1).

Besides the relativistic kinematic effects, as, for exam-ple, the length contraction, the concept of size and shape inrelativistic quantum systems, such as hadrons, is also pro-foundly modified as the number of degrees of freedom isnot fixed anymore. In relativistic quantum mechanics thenumber of constituents of a system is not constant as aresult of virtual pair production. We consider as an exam-ple a hadron such as the proton which is probed by a space-like virtual photon, as shown in Figure 5. A relativisticbound state as the proton is made up of almost masslessquarks. Its three valence quarks making up for the protonquantum numbers, constitute only a few percent of the totalproton mass. In such a system, the wave function contains,besides the three valence quark Fock component ,also components where additional pairs, the so-calledsea-quarks, and (transverse) gluons g contribute leading toan infinite tower of components.When probing such a system using electron scattering, theexchanged virtual photon will couple to both kind ofquarks, valence and sea, as shown in Figure 5a and b. In

addition, the virtual photon can also split into a qq- pair,leading to a transition from a 3q state in the initial wavefunction to a 4qq- state in the final wave function, as depictedin Figure 5c. Such processes representing non-diagonaloverlaps between initial and final wave functions are notpositive definite and do not allow for a simple probabilityinterpretation of the density r anymore. Only the processesshown in Figure 5a and b, with the same initial and finalwave function yield a positive definite particle densityallowing for a probability interpretation.

This relativistic dynamic effect of pair creation or anni-hilation fundamentally hampers the interpretation of den-sity and any discussion of size and shape of a relativisticquantum system. Therefore, an interpretation in terms ofthe concept of a density requires suppressing the contribu-tions shown in Figure 5c. This is possible when viewingthe hadron from a light front reference frame allowing for adescription of the hadron state by an infinite tower of light-front wave functions [19]. Consider the electromagnetic(e.m.) transition from an initial hadron (with four-momen-tum p) to a final hadron (with four-momentum p′) viewedfrom a light-front moving towards the hadron. Equivalently,this corresponds to a frame where the hadrons have a largemomentum-component along the z-axis chosen along thedirection of the hadrons average momentum P = (p + p′)/2.One then defines the light-front plus (+) component bya+ ≡ a0 + a3, in a general four-vector am, which is always apositive quantity for both quark or anti-quark four-momenta

|qqq⟩q q

_

| | . qqqq q qqqg_⟩ ⟩, , . .

r [fm]0.0

–0.10

–0.05

0.00

0.05

0.10

0.15

0.5

(4πr

2 ) *

ρ 3dn [1

/fm]

1.0 1.5 2.0 2.5

Figure 4. Charge distribution of the neutron as derivedfrom the Fourier transform of the GEn fit (solid red curve inFigure 3). The dashed part of the curve is for r < λlim = 2π/(2M), where one is intrinsically limited to resolve thedensity due to the “Zitterbewegung” of the nucleon.

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in the hadron. When we now view the hadron in a so-calledDrell-Yan frame [20], where the virtual photon four-momentum q satisfies q+ = 0, energy-momentum conserva-tion will forbid processes in which this virtual photon splitsinto a pair. Such a choice is possible for a space-likevirtual photon, and its four-momentum or “virtuality” isthen given by where is thetransverse photon momentum lying in the xy-plane. In sucha frame, the virtual photon only couples to forward movingpartons, that is, only processes such as in Figure 5 (a) and(b) are allowed. We can then define a proper density opera-tor through the + component of the four-current by J+ = J0

+ J3 [21]. For quarks it is given by

where we introduced the q+ fields through a field redefini-tion from the initial quark fields q involving the ± compo-nents of the Dirac gamma matrices. The relativistic densityoperator J+, as defined in Eq. (3), is a positive definitequantity. For systems consisting of, for example, light uand d quarks, multiplying this current with the quarkcharges yields a quark charge density operator given byJ+(0) = +2/3 (0)γ+u(0) − 1/3 (0)γ+(0)d(0). Using thischarge density operator, one can then define quark (trans-verse) charge densities in a hadron as [22–23]:

where the hadron is in a state of definite (light-front)helicity. In the two-dimensional Fourier transform of Eq.(4), the two-dimensional vector denotes the quark posi-tion in the xy-plane relative to the position of the trans-verse centre-of-momentum of the hadron. It representsthe position variable conjugate to the hadron relativetransverse momentum, which equals just the photonmomentum .

The quantity r0(b) has the interpretation of the two-dimensional unpolarized quark charge density at a distance

from the origin of the transverse c.m. system of thehadron. In the light-front frame, it corresponds to the pro-jection of the charge density in the hadron along the line-of-sight. It is important to mind this difference to the inter-pretation in the non-relativistic case.

The quark charge density in Eq. (4) does not fullydescribe the e.m. structure of the hadron, because we knowthat there are two independent e.m. FFs describing thestructure of the nucleon. In general, a particle of spin S isdescribed by (2S + 1) e.m. moments. In order to fullydescribe the relativistic structure of a hadron one needs toconsider additionally the charge densities in a transverselypolarized hadron state yielding a transverse charge distri-bution . We denote the transverse polarization direc-tion by The transverse chargedensities can then be defined through matrix elements ofthe density operator J+ in eigenstates of transverse spin as[24–26]:

where s⊥ is the hadron spin projection along the directionof . Whereas the density r0 for a hadron in a state ofdefinite helicity is circular symmetric for all spins, thedensity depends also on the orientation of the posi-tion vector , relative to the transverse spin vector .Therefore, it contains the information on the hadronshape, again projected on the plane perpendicular to theline-of-sight.

As summarized in the previous section, e.m. FFs of thenucleon are well measured experimental quantities. Wewill, therefore, discuss the relativistic spatial shape asderived from these FFs. For a nucleon in a state of definitehelicity, the transverse quark charge density is obtained

q q_

q q Q2 2 2 0= − ≡ − <→⊥ , q

→⊥

J q q q q q q+ +++

+ +− +≡= = 2 ,

1

4,g g gwith (3)

u d

rp0 ( )

(2 )

1

2

2

2b

d qe

Piq b≡

+⊥ − ⋅⊥

��

× + − ++ ⊥ + + ⊥Pq

J Pq

,2

,1

2(0) ,

2,

1

2,

� �| | (4)

b→

q→

⊥

b b= | |�

rT s⊥S s e s ex y⊥

∧ ∧+= (cos sinf f

rpTs

i qb

d qe

b

P⊥

⊥ − ⊥+≡ ⋅∫( )

(2 )

1

2

2

2

� � ��

×−+ ⊥

⊥+ + ⊥

⊥Pq

s J Pq

s,2

, | | ,2

, ,� � (5)

�S⊥

rT s⊥ �b

�S⊥

(a) (b) (c)

Figure 5. Coupling of a space-like photon to a relativisticmany-body system, such as the proton. Top panel (a):diagonal transition where the photon couples to a quark inthe leading 3q Fock component of the proton. Middle panel(b): diagonal transition where the photon couples to a quarkin a higher Fock component (here 4qq- ) of the proton. Lowerpanel (c): process where the photon creates a qq- pair.

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from Eq. (4) by taking the two-dimensional Fourier trans-form of its Dirac FF F1 = (GE + tGM)/(1 + t) as [22–23]:

where Jn denotes the cylindrical Bessel function of order n.Note that r0 only depends on .

On the other hand, the information encoded in the PauliFF F2 = (GM − GE)/(1 + t) is connected to a nucleon in atransverse spin state. For a nucleon polarized along thepositive x-axis, the transverse spin state can be expressedin terms of the light front helicity spinor states by:

. The Fou-rier transform given in Eq. (5) in a state of transverse spin

then yields [24]

The second term, which describes the deviation from thecircular symmetric unpolarized charge density, dependson the orientation of the transverse position vector

rp0 0 1

2

0( ) =

2( ) ( ),b

dQQ J bQ F Q

∞

∫ (6)

b b= | |�

| = 1/2 = | = 1/2 | = 1/2 / 2s ei S

⊥ + ⟩ + ⟩ + − ⟩( )l lf

s⊥ += 1/2

r r

f fp

T

b s

b bdQ Q

MnJ bQ F Q

1

2

02

1 22

0

( ) = ( )

( )2 2

( ) ( )

�

+ −∞

∫sin . (7)

Figure 6. Quark transverse charge densities in the proton (left panels) and neutron (right panels). The upper panels showthe density in the transverse plane for a nucleon with definite helicity. The lower panels for a nucleon polarized along thex-axis. The light (dark) regions correspond with largest (smallest) values of the density. For the proton e.m. FFs, theempirical parametrization of Arrington et al. [27] is used. For the neutron e.m. FFs, the empirical parametrization ofBradford et al. [28] is used.

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relative to the transverse spindirection.

In Figure 6, the transverse charge densities in anucleon, polarized transversely along the x-axis (i.e., for fS

= 0), are extracted based on the empirical information onthe nucleon e.m. FFs which, however, does not yet containthe most recent data presented in the second section. Forthe proton e.m. FFs, the empirical parametrization of Ref.[27] is used, whereas for the neutron e.m. FFs, the empiri-cal parametrization of Ref. [28] is taken. One notices fromFigure 6 that polarizing the proton along the x-axis leads toan induced electric dipole moment along the positive y-axis equivalent to the anomalous magnetic moment mN.This field pattern, due to the induced electric dipole, is aconsequence of special relativity. The nucleon spin alongthe x-axis is the source of a magnetic dipole field . Anobserver moving toward the nucleon with velocity willsee an electric dipole field pattern with giving rise to the observed asymmetry.

For the neutron, one notices its charge density gets dis-placed significantly due to its large negative anomalousmagnetic moment mN = −1.91 yielding an induced electricdipole moment along the negative y-axis.

In order to extract charge densities, one requires a formfactor parametrization over all values of Q2. Because theBernauer et al. [4] data only provide a precision measure-ment of GEp and GMp for Q2 ≤ 0.4 GeV2, to fully quantifytheir impact on quark charge densities requires a new glo-bal analysis combining the previous data with these newdata. Here we will perform a first estimate of this by usinga parametrization that smoothly connects the new high pre-cision data at low Q2 and the Arrington et al. [27] parame-trization at larger Q2. This interpolation function is used toextract the two-dimensional quark charge density in a pro-ton in Figure 7. One readily sees that the new high preci-sion data have a direct impact on the extracted chargedensities at large distances, typically larger than about 1.5 fm.By comparing the extracted density, using the previous fitto world data with the new fit, one sees that the new datalead to a significant reduction of the densities at distanceslarger than about 2 fm. This is a direct consequence of theflatter behavior in Q2, for Q2 ≤ 0.3 GeV2, which the newdata display for both GEp and GMp.

In Figure 8, we show the corresponding large distancebehavior of the quark charge density in the neutron. Thetransition between the dashed blue curve and the solid redcurve in Figure 8 shows the impact of recent precision dataat low Q2 for the neutron FFs. These lead to a sizableenhancement in the extracted densities at distances largerthan 1.5 fm. It is also of interest to compare these light-front densities with the static densities as discussed in thesecond section. For a non-relativistic system, one canextract from the 3-dimensional static density of Eq. (2),with intrinsic form factor ~r (k) = GE(k2), a 2-dimensionalstatic density as:

One notices that this static 2-dimensional density has thesame form as the light-front density, see Eq. (6), with thecrucial difference that in the static density the Sachs elec-tric FF GE appears, whereas for a relativistic system, theproper light-front charge density involves the Dirac FF F1.Since the large distance behavior is mostly impacted by thelow Q2 data, where GE is dominated by F1, one expects aqualitatively similar behavior at large distances betweenboth pictures. This is illustrated in Figures 7 and 8 wherethe light-front densities (solid red curves) are depicted

�b b e eb x b y= ( )cos sinf f∧ ∧+

B→

u→

E B′→ → →

= − ×g u( )

r r2 32 2( ) =d db dz b z( ),+

−∞

+∞

∫=

+∞

∫ dQQ J bQ G QE2 0

0

2

p( ) ( ).

(8)

b [fm]

1.60.00

0.01

0.02

0.03

0.04

0.05

0.06

1.8 2.0 2.2 2.4

(2πb

) *

ρ 0p [1

/fm]

Figure 7. Large distance behavior of the unpolarizedquark transverse charge density in the proton. The dashedblue curve uses the Arrington et al. parametrization [27].The solid red curve shows the impact of recent highprecision data at low Q2 by using a smooth connectionbetween the Bernauer et al. [4] fit at low Q2 and theArrington et al. fit at larger Q2. For comparison, the dottedblack curve is the 2-dimensional projection of the staticcharge distribution according to Eq. (8), using theinterpolating fit for GEp.

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along with the 2-dimensional static densities (dotted blackcurves). One notices that for the proton, both densitiesapproach each other at large distances pointing to a largetail in the charge distribution. The corresponding picturefor the neutron shows that both light-front and static densi-ties display a negative charge density for distances largerthan about 1.6 fm, which can be associated with a negativepion cloud in the outer region of the neutron.

A combination of the FF data for the proton and neu-tron allows one to perform a quark flavor separation andmap out the spatial dependence of up and down quarksseparately. The flavor separated FFs, invoking isospinsymmetry, are defined as

For the Pauli FFs, it is convenient to divide out the normal-izations at Q2 = 0, given by the anomalous magneticmoments ku = 2kp + kn, kd = kp + 2kn.

Using Eq. (6), we can then extract the ratio of up/downquark densities in the nucleon, which is displayed in Figure9. If the down and up quarks would have the same spatialdistribution in the nucleon, the ratio as displayed in Figure9 would be one. We see, however, that in the center regionof the proton, at distances smaller than about 0.5 fm, downquarks are less abundant than up quarks. The down quarkshave a much wider distribution and are shifted to largerdistances, dominating over up quarks between 0.5 to 1.5fm. At large distances, larger than about 1.5 fm, one clearlysees the impact of the recent data, which results in a factor2 change in the density as compared to previous fits toworld data. Although the contribution of the large distanceregion to the total charge is very small, the new data allowone to precisely map out the charge densities in the regionwell beyond the confinement radius, where the charge den-sity can in turn be interpreted as a measure of the contribu-tion of the pion cloud.

Conclusion We have presented two ideas about the long-range

structure of the nucleon. The first is nonrelativistic in termsof a “bare nucleon” plus a pion cloud, and the second rela-tivistic in terms of quarks and gluons. One may be temptedto believe that the second is more fundamental since it usesthe elementary fields of the standard model of particlephysics. The quantum theory of quarks and gluons, QCD,

describes a very large domain of strong interaction physicsindeed. However, at sufficiently low energies, hadrons maybe described by effective field theories formulated in termsof fields with discrete quantum numbers. These fields maybe viewed as elementary in a certain domain of validity(i.e., sufficiently low energies here). One prominent exam-ple of such an effective field is just the pion in Chiral Per-turbation Theory emerging as the Goldstone Boson of thespontaneous breaking of chiral symmetry of QCD.

In fact, we are not able to devise a quantitative descrip-tion of the nucleon-nucleon force in terms of quarks andgluons. On the other hand, the meson exchange idea allowsfor a very precise description of this force. Therefore, itmay be futile to ask the question which description is morecorrect. Frequently in physics we have to be content with amodel allowing a description in a limited domain and, fol-lowing from this, limited predictive power.

This sometimes confusing situation is also revealed bythe two extreme reference frames in which we have con-sidered the structure of the nucleon: the brick-wall systemimplying an infinitely heavy nucleon and the light-frontframe implying a nucleon moving with approximately thespeed of light. As we demonstrated in both frames, thelong distance structure of the nucleon reflects the physicsof the pion cloud. However, whether we will ever be ableto devise a “final theory” in terms of the elementary fieldsis an open question. Actually, most physics is understood

F F F

F F F

u p n

d p n

1 2 1 2 1 2

1 2 1 2 1 2

2

2

, , . ,

, , . ,

= +

= +(9)

b [fm]

–0.005

1.6 1.8 2.0 2.2 2.4

–0.010

(2πb) * ρ0n [1/fm]

Figure 8. Large distance behavior of the unpolarizedquark transverse charge density in the neutron. The dashedblue curve is the smooth part of the Friedrich-Walcherparametrization [14]. The solid red curve is the updatedFriedrich-Walcher parametrization which includes therecent neutron FF data at low Q2. For comparison, thedotted black curve is the 2-dimensional projection of thestatic charge distribution according to Eq. (8), using themost recent fit for GEn.

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in terms of emergent effective degrees of freedom as theexamples of condensed matter physics and nuclear physicsshow overwhelmingly.

Acknowledgments We thank J. Friedrich, K. de Jager, V. Pascalutsa, and

L. Tiator for helpful correspondence and discussions.

References 1. M. Vanderhaeghen and Th. Walcher, arXiv:1008.4225

[hep-ph]. 2. B. Povh and Th. Walcher, Comments Nucl. Part. Phys. 16

(1986) 85. 3. L. D. Landau and E. M. Lifshitz, Course of Theoretical Physics,

Vol. IV Quantum Electrodynamics, eds., W. B. Berestetskii,E. M. Lifshitz, and L. P. Pitaewskii (Butterworth-Heinemann,Reed-Elsevier Group, Oxford 1971).

4. J. Bernauer, Ph.D., Thesis, Mainz University 2010; J. C.Bernauer et al., Phys. Rev. Lett. 105 (2010) 242001. arXiv:1007.5076 [nucl-ex].

5. C. E. Hyde-Wright and K. de Jager, Ann. Rev. Nucl. Part. Sci.54 (2004) 217.

6. J. Arrington, C. D. Roberts, and J. M. Zanotti, J. Phys. G 34(2007) S23.

7. C. F. Perdrisat, V. Punjabi, and M. Vanderhaeghen, Prog.Part. Nucl. Phys. 59 (2007) 694.

8. C. Crawford et al., Phys. Rev. C82 (2010) D45211. arXiv:1003.0903v3 [nucl-th].

9. C. N. Hand, D. J. Miller, and R. Wilson, Rev. Mod. Phys. 35(1963) 335.

10. P. J. Mohr, B. N. Taylor, D. B. Newell, and B. David, Rev.Mod. Phys. 80 (2008) 633.

11. D. Drechsel and Th. Walcher, Rev. Mod. Phys. 80 (2008) 731. 12. M. A. Belushkin, H. W. Hammer, and U. G. Meissner, Phys.

Rev. C 75 (2007) 035202. 13. R. Pohl et al., Nature 466 (2010) 213. 14. J. Friedrich and T. Walcher, Eur. Phys. J. A 17 (2003) 607. 15. M. Guidal, M. V. Polyakov, A. V. Radyushkin, and M.

Vanderhaeghen, Phys. Rev. D 72 (2005) 054013. 16. E. Geis et al. [BLAST Collaboration], Phys. Rev. Lett. 101

(2008) 042501. 17. S. Riordan et al., Phys. Rev. Lett. 105 (2010) 262302 submit-

ted to PRL, arXiv:1008.1738v1 [nucl-ex] 18. J. J. Kelly, Phys. Rev. C 66 (2002) 065203. 19. S. J. Brodsky, H. C. Pauli, and S. S. Pinsky, Phys. Rept. 301

(1998) 299. 20. S. D. Drell and T. M. Yan, Phys. Rev. Lett. 24 (1970) 181. 21. L. Susskind, Phys. Rev. 165 (1968) 1547. 22. M. Burkardt, Phys. Rev. D 62 (2000) 071503; Int. J. Mod.

Phys. A 18 (2003) 173. 23. G. A. Miller, Phys. Rev. Lett. 99 (2007) 112001. 24. C. E. Carlson and M. Vanderhaeghen, Phys. Rev. Lett. 100

(2008) 032004. 25. C. E. Carlson and M. Vanderhaeghen, Eur. Phys. J. A 41

(2009) 1. 26. C. Lorcé, Phys. Rev. D 79 (2009) 113011. 27. J. Arrington, W. Melnitchouk, and J. A. Tjon, Phys. Rev. C 76

(2007) 035205. 28. R. Bradford, A. Bodek, H. Budd, and J. Arrington, Nucl.

Phys. Proc. Suppl. 159 (2006) 127.

b [fm]0.0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0.5 1.0 1.5 2.0

ρ 0d

/ (ρ 0

u /2)

Figure 9. Ratio of down over up quark densities in theproton. The dashed blue curves represent a previous fit toworld data, whereas the solid red curves show the impactof recent high precision data at low Q2 as described in thetext. The dotted black curves represent the results of aGeneralized Parton Distribution parametrization [15] ofup and down quarks.

facilities and methods


Extreme Light Infrastructure–Nuclear Physics (ELI–NP): New Horizons for Photon Physics in Europe

The European Strategy Forum onResearch Infrastructures (ESFRI) andits roadmap [1] aim to integratenational resources into a common,pan-European effort. Currently theESFRI roadmap, first issued in 2006and updated in 2008, lists 43 large-scale projects selected from allscience and engineering areas. Underthe 7th Framework Programme theEuropean Commission has funded thepreparatory phases for 34 projectsincluded in the 2006 ESFRI roadmap.In the area of physical sciencesbesides the two radioactive beamfacilities FAIR (at GSI/Germany) andSPIRAL2 (at GANIL/France) also theproject “Extreme Light Infrastructure”

(ELI) [2] was selected. Already oneyear before the end of ELI’s 7thFramework Preparatory Phase a deci-sion was made in October 2009 toimplement ELI as a joint Europeanconsortium of 17 nations consisting ofthree laser facilities that will be con-solidated under the joint ELI project.The prime objective is to build a uni-fied infrastructure based on threemutually supporting pillars.

One pillar will be located inPrague (Czech Republic), focusing onbuilding a novel generation ofsecondary sources from high energylaser beams for interdisciplinaryapplications in physics, medicine,biology, and material sciences [3].

The second pillar, concentrating onthe physics of ultrashort optical pulseson the attosecond scale, is scheduledfor location in Szeged (Hungary)[4]. Finally, the third pillar will bebuilt in Magurele, close to Bucharest(Romania) and will be dedicated to(photo-)nuclear physics [5], thereforetermed ELI–Nuclear Physics (ELI–NP). With the termination of ELI’sPreparatory Phase end of November2010 and with funding of 280 millionEuros in the process of being allo-cated from EU structural funds forELI–NP in Romania, ground breakingfor ELI–NP should start as early as2011.

The laser backbone of ELI–NPwill consist of several arms of high-power, short-pulse lasers, each ofthem providing 10 Petawatt laserpower (Table 1). These “APOL-LON”-type lasers are currently beingdeveloped by the group of GerardMourou and coworkers at the ÉcoleNationale Supérieure de TechniquesAvancées (ENSTA) in Paris [6].Here, a future fourth pillar of ELI isprepared, where many APOLLONlasers are envisaged to be combinedfor high-field science. The secondsource of ELI–NP, the γ-beam facility(Table 1), will be developed and pro-vided by the group of Chris Barty atLawrence Livermore National Labo-ratory (LLNL). Brilliant, intense, andenergetic photon beams will be gener-ated via Compton backscattering oflaser photons from a high-qualityelectron beam [7]. The Livermoregroup is presently building a similarfacility called MEGa-ray [8], with anormal-conducting electron linac

Table 1. Characteristics of the ELI–NP linear Compton back-scattering γ source and the high-powerlasers.

Parameters of g-beam Value Parameters of APOLLON lasers Value

max. e energy 600 MeV power 2 · 10 PW

max. γ energy 13.2 MeV (19.5 MeV) OPCPA front end

norm. emittance 0.18 mm mrad Ti:Sapphire

γ-energy spread (FWHM) 10−3 high energy end

total flux (ph/s) 1013 100 TW 10 Hz

pulse repetition (macro p.) 12 kHz (120Hz) 1 PW ≥0.1 Hz

pulse duration 2 ps 10 PW 1/min

γ source size 10 μm max. intensity 1024 W/cm2

peak brilliance 1.5 · 1021 max. field strength ≈1015 V/m

ph/(mm2 mrad2 s 0.1% BW) pulse duration 15 fs

average brilliance 4 · 1012 contrast (10 ps before)

10−12

ph/(mm2 mrad2 s 0.1% BW)



based on X-band technology. Thisfacility is a continuation of their previ-ous γ-ray facilities PLEJADES [9] andT-REX [10]. Hence, the long-termexpertise of the groups responsible forthe key components of ELI-NP raiseconfidence for a timely completion ofthe main driver facilities for ELI–NP.

In this article, at a rather earlystage of the project, we will outlinethe scope of ELI–NP. We will presentthe broad range of the physics casestargeted within ELI–NP, coveringmany facets of photonuclear reac-tions, but also astrophysics and funda-mental physics. Moreover, we willillustrate the various perspectives forapplications ranging from medicine tomaterial science, life science, andradioactive waste management.

The experiments can be groupedinto three categories: stand-aloneγ-beam experiments, stand-aloneAPOLLON-type laser experiments,and combined experiments makinguse of both drivers, for example, the600 MeV electron beam (for theγ-beam) and the high power lasers.

The layout of the ELI–NP facil-ity, covering an area of about twofootball fields, is shown in Figure 1.It consists of two 10 PW lasers,shown in the upper part of the figure,which can be added phase-synchro-nized into a common focus. In thelower part the normal-conductingelectron linac is shown, delivering γbeams from two beam ports. Thehigh spatial accuracy of the beamsrequires a special design of the

concrete base plate of the building toprevent vibrations. The laser hall willrequire clean-room conditions ofclass 6. The large amount of radio-protection concrete shielding isdesigned in a modular way to acco-modate the planned experiments witha maximum of flexibility. Finally, anarchitect’s vision of the ELI–NPfacility is shown in Figure 2.

Nuclear Physics and Astrophysics

Experiments with Stand-Alone APOLLON-Type Lasers

The origin of the heaviest ele-ments (e.g., gold, platinum, thorium,uranium) remains one of the 11 great-est unanswered questions of modernphysics, according to a recent reportby the U.S. National Research Coun-cil of the National Academy ofScience [11]. A recent paper [12] out-lines in detail, how dense, laser-accel-erated ion beams open up a newaccess to very neutron-rich nuclei,relevant to this element production. Inthis proposal, we introduced the new“fission–fusion” nuclear reaction pro-cess that allows one to produce thedecisive extremely neutron-richnuclei in the range of the astrophysi-cal r-process (the rapid neutron-capture process around the waitingpoint N = 126 [13, 14] by fissioning adense, laser-accelerated thorium ionbunch in a thorium target (coveredby a polyethylene layer), where thelight fission fragments of the beamfuse with the light fission fragmentsof the target. So far the astrophysi-cally relevant nuclei are about 15 neu-trons away from the last knownisotope of a given element and noth-ing is known about their nuclear prop-erties (Figure 3).

Via the “hole-boring” (HB) mode oflaser Radiation Pressure Acceleration

Figure 1. Layout of the ELI–NP facility.



(RPA) [15, 16] using a high-intensity,short pulse laser bunches of 232Thwith solid state density can be gener-ated very efficiently from a Th layer(approx. 0.5 μm thick), placed on adeuterated diamond-like carbon foil[CD2]n (with approx. 0.5 μm thick-ness), forming the production target.Laser-accelerated Th ions with about7 MeV/u will pass through a thin[CH2]n layer placed in front of athicker second Th foil (both formingthe reaction target) closely behindthe production target and disintegrateinto light and heavy fission frag-ments. In addition, light ions (d,C)from the [CD2]n backing of the Thlayer will be accelerated as well,inducing the fission process of 232Thalso in the second Th layer. Thelaser-accelerated ion bunches withnear solid state density, which areabout 1014 times more dense thanclassically accelerated ion bunches,allow for a high fusion probability of

the generated fission products whenthe fragments from the thorium beamstrike the thorium layer of the reac-tion target.

In contrast to classical radioactivebeam facilities, where intense butlow-density radioactive beams of oneion species are merged with stable tar-gets, the novel fission–fusion processdraws on the fusion between high-density, neutron-rich, short-lived,light fission fragments both frombeam and target. Moreover, the highion beam density may lead to a strongcollective modification of the stop-ping power in the target by “snow-plough-like” removal of targetelectrons, leading to significant rangeenhancement, thus allowing one touse rather thick targets.

Using a high-intensity laser with300 J and 32 fs pulse length, as, forexample, envisaged for the ELI–Nuclear Physics project in Bucharest(ELI–NP), order-of-magnitude esti-mates promise a fusion yield of about103 ions per laser pulse in the massrange of A = 180 − 190, thus enablingto approach the r-process waitingpoint at N = 126. The produced nucleifrom the fission–fusion process will

Figure 2. Architect’s view of the ELI–NP facility.

Figure 3. Nuclidic chart, showing the different nucleosynthesis processes likethe r-process, the s-process, or the fusion processes in stars together withcontour lines of the new fission–fusion process for producing very neutron-richnuclei close to N = 126 waiting point of the r-process.



be injected into a Penning trap tomeasure their nuclear binding energy,a measure for shell quenching, withhigh accuracy [12]. This informationwill constrain possible sites for theastrophysical r-process decisively.

Experiments with g-Beams Employing intense, brilliant γ

beams the fine structure of many E1and M1 excitations can be probed indetail with their many decaybranches. Specific parity-violatingmixtures between parity doublets(e.g., 1+ and 1− states) allow a verysensitive access to parity violatingnuclear forces [17]. The gatewaystates to switch from the ground statevia γ-excitation–deexcitation to alonger-lived isomer or from oneisomer to the next with still higherspin and K quantum number can beexplored in detail. The transition fromregular nuclear motion at lower ener-gies to chaotic nuclear motion athigher excitation energies, whichrecently has been reviewed in detail[18], can be studied by manytools like nearest-neighbor level dis-tributions or Porter-Thomas width

distributions. Very high-resolutionγ spectrometers, similar to the GAMSspectrometer at ILL [19], will becomemore important. Once we reach exci-tation energies with particle unstablestates, fine structures like the PygmyDipole Resonance (PDR) becomeimportant for astrophysical processes.

Fundamental Physics

Pair Creation from the Vacuum with 600 MeV Electrons Seeding a very Intense Laser Focus

The typical quasi-static thresholdelectric field for pair creation fromthe vacuum is Es = m2c3/eh = 1.3.1018

V/M, which correspond to laserintensities of 4.3.1029 W/cm2. Due tothe very strong exponential depen-dence of the pair production rate [20]in the focused laser fields of ELI–NP, we cannot reach pair creationwith the laser field alone. Here, NinaElkina and colleagues [21] of Hart-mut Ruhl’s group (LMU, Munich)performed detailed simulationsfocussing 600 MeV electrons asseeds into the focus of two counter-propagating circularly polarizedAPOLLON-type lasers. By stronglynon-linear quantal effects the elec-trons emit hard γ rays (up to 500MeV) in the laser focus, which thenin a second step decay into e+e− pairs.These pairs are re-accelerated, result-ing in further hard γ rays and pairs.Elkina’s simulations showed a qua-dratic increase of pairs in the laserfocus with time, less than exponen-tial, due to the loss of electrons andpositrons from the focal laser region.At ELI–NP this strong radiationdamping, the predicted spectra andangular distributions of hard γ rays,electrons and positrons will be com-pared to experimental data, resultingin conclusive tests of the computer

simulations for strong laser-fieldinteraction.

Searching for Light Elementary Particles with High Power Lasers

In stand-alone experiments withthe APOLLON-type lasers the fun-damental properties of vacuum canbe probed. Here, Kensuke Hommaand colleagues [22] have proposednew experiments: Very light elemen-tary particles below 1 eV (like candi-dates of dark energy) couple veryweakly to matter and have not beendetected until now. Here, the veryintense semi-macroscopic laser fieldsmay open a new window to findthese new particles via coupling tolaser photons, by observing the gen-eration of second-harmonic radia-tion in the quasi-parallel collidingsystem of a single focused laser.Schematically this experiment isshown in Figure 4.

Applications With the γ-beam of ELI–NP sev-

eral new applications can be devel-oped, giving many nuclear excitationcross-sections a new importance.Many of the applications (e.g., inmedicine or radioactive materials andradioactive waste management) opennew perspectives in a socioeconomi-cal context.

New Medical Radioisotopes Produced with g-Beams

In Ref. [23] about 50 radioisotopesare described, which can be producedwith better specific activity and abso-lute activity by γ beams compared topresent production schemes, being ofinterest for medical diagnostic and/ortherapeutic purposes. With the narrowbandwidth γ beams we will find spe-cific gateway states or groups of reso-nant states for many of the isotopes,

Figure 4. Suggested experimentalsetup to detect low-mass elementaryparticles by mediating the two photontransition in vacuum of an intenselaser focus.



where the production cross-sectionscan be increased by 2–3 orders ofmagnitude compared to the existingaverage cross-sections [23], makingthem even more interesting for large-scale industrial applications. Here weshall focus on some of the most inter-esting isotopes to give a flavor of thenew possiblities.

195mPt: Determining the efficiency of chemotherapy for tumors and the optimum dose by nuclear imaging Inchemotherapy of tumors most oftenplatinum cytotoxic compounds likecisplatin or carbonplatin are used.We want to label these compoundswith 195mPt for pharmacokinetic stud-ies like tumor uptake and want toexclude “nonresponding” patientsfrom unnecessary chemotherapy,while optimizing the dose of all che-motherapy treatments. For such typeof diagnostics a large-scale marketcan be foreseen, but it would alsosave many people from painful butuseless treatments. It is estimated inRef. [23] that several hundredpatient-specific uptake doses couldbe produced with a γ beam facilityper day. However, this probably maybe increased to 105, if optimum gate-way states can be identified by scan-ning the isomer production with highγ beam resolution.

117mSn: An emitter of low-energy Auger electrons for targeted tumor therapy Auger-electron therapy requirestargeting into individual tumor cells,even into the nucleus or to the DNA,due to short range (below 1μm) ofAuger electrons; however, thismethod is of high relative biologicalefficiency (RBE) due to the shower ofmany (typically 5–30) Auger elec-trons produced. On the other hand,Auger radiation is of low toxicity,while being transported through thebody. Thus Auger-electron therapy

needs special tumor-specific transportmolecules like antibodies or peptides.Many of the low-lying high spin iso-mers produced in (γ,γ ′) reactions havestrongly converted transitions, whichtrigger these large showers of Augercascades.

A variety of other important medi-cal radioisotopes can be produced(see Ref. [23]): New “matched pairs”of isotopes of the same elementbecome available, one for diagnostics,the other for therapy, allowing to con-tol and optimize the transport of theisotope by the bioconjugate to thetumor. Also new therapy isotopesbecome available, such as 225Ac,where four consecutive α decays cancause much more efficiently DNAdouble-strand breaking. Developingthese techniques and applications is apromising task of ELI–NP with astrong societal impact.

New Brilliant, Intense Micro-Neutron Source Produced by Intense, Brilliant g-Beam

ELI–NP includes the proposal todevelop a brilliant, low-energy neutronbeam from the γ beam. In Ref. [24], itis described in detail, how low-energyneutrons will be released withoutmoderation and without producing abroad range of fission fragments as innuclear reactors, or a broad range ofspallation products as in spallationneutron sources. Thus, the new neu-tron facility has the advantage of pro-ducing only small amounts ofradioactivity and radioactive wasteand thus requires only moderateefforts for radioprotection, thereforebeing very different from presentreactor or spallation facilities. Thenew source can be operated as amulti-user neutron facility and coulddeliver several orders of magnitude

Figure 5. Schematic picture of the new neutron production scheme, using theg-beam to excite neutron-halo isomers with a neutron separation energy SN belowthe binding energy EB. The left level scheme shows the increasing number ofcompound nuclear resonances as a function of the excitation energy. The haloisomer is fragmented into several high-lying resonances, resulting in halo isomerswith different binding energies. The two blue arrows indicate the width of the gbeam. Then in a second step, a photon beam of much lower energy, shown in red,generates the neutron beam by dissociating the neutron halo states.



more brilliant neutrons compared tothe best existing neutron sources.When producing the neutrons, weenvisage to use a two-step process:with the high-energy γ beam in a firststep neutron-halo isomers will bepopulated, while in a second step neu-trons are released from the stoppedneutron-halo isomers by a secondphoton pulse (Figure 5).

For the realization of such a neu-tron source we first plan to study thenew neutron-halo isomers in detail.We propose to search for neutron-halo isomers populated via γ capturein stable nuclei with mass numbers ofabout A = 140–180 or A = 40–60,where the 4s1/2 or 3s1/2 neutron shellmodel states reach zero binding energy.These halo nuclei can be produced forthe first time with the new γ beams ofhigh intensity and small band width.This production scheme thus offers apromising perspective to selectivelypopulate these isomers with small sepa-ration energies of 1 eV to a few keV.Similar to single-neutron halo states forvery light, extremely neutron-rich,radioactive nuclei [25], the low neutron

separation energy and short-rangenuclear force allows the neutron to tun-nel far out into free space, muchbeyond the nuclear core radius. Thisresults in prolonged half-lives of theisomers for the γ-decay back to theground state in the 100 ps-μs range.Similar to the treatment of photodisin-tegration of the deuteron, the neutronrelease from a neutron-halo isomer viaa second, low-energy, intense photonbeam has a much larger cross-sectionwith a typical energy-threshold behav-ior. In the second step, the neutrons canbe released as a low-energy, pulsed,polarized neutron beam of high inten-sity and high brilliance.

Similar to the situation 30 yearsago, when synchrotron sources led toincreases in brilliance of x-ray beamsby many orders of magnitude, theproduction of pulsed neutron beamswith extremely high brilliance willlead to a dramatic leap in the field ofneutron scattering. The well focusedbeams of highest intensity will allowthe accurate determination of thestructure of biological samples, het-erostructures, and of new functional

materials. These materials are oftenonly available in small quantities.The exceptionally strong scatteringof neutrons by hydrogen and otherlight materials will provide keyinformation concerning the function-ality of bio-materials, which cannotbe easily obtained using synchrotronbeams or existing neutron sources. Inaddition, the brilliant neutron beamswill allow for the first time the inves-tigation of collective excitations (i.e.,magnons and phonons), and relax-ation as well as diffusion processesin samples that are only available insmallest quantities. Moreover, the byorders of magnitude smaller durationof the neutron pulses will allow forthe investigation of time-dependentprocesses and the dynamics in sys-tems far away from equilibrium. Thenew neutron beams will thereforeopen completely new scientificopportunities in the fields frombiology to hard condensed matter togeosciences and nuclear physics. InRef. [24] many new possibilities aredescribed in more detail.

Nuclear Resonance Fluorescence of Nuclear Materials and Nuclear Waste Management

The non-destructive detection ofmaterials hidden by heavy shields suchas iron with a thickness of several cen-timeters is difficult. Such detection ofclandestine materials is of importance,for example, for applications in nuclearengineering: the management ofnuclear materials produced by nuclearpower plants, the detection of nuclearfissile material in the recycling pro-cess, and the detection of explosivematerials hidden in packages or cargocontainers. A non-destructive assay[26] has been proposed with theextremely high-flux Laser ComptonScattering (LCS) γ source. The

Figure 6. Nuclear resonance fluorescence of several actinides, demonstratingthe high sensitivity of the method [26].



elemental and isotopic composition ismeasured using nuclear resonancefluorescence (NRF) with LCS γ-rays.Figure 6 illustrates how characteristicresonances of these elements can beidentified via NRF.

Here, one has to stress the politicalimportance of this project. Measuringremotely and precisely isotopes like239Pu, 235U or dominant fission prod-ucts is very important for radioactivewaste management. The handling ofradioactive waste and its long-termstorage are partially unsolved prob-lems not only in Europe but world-wide, as exemplified by the stronginterest and encouragement by IAEAon this development.

Acknowledgments A large number of persons have

contributed to the development of theELI–NP project, but also to ELI in gen-eral, to all of them we are very grateful.However, we cannot name these peopleindividually, since, for example, morethan 100 people have contributed to theELI–NP Whitebook and to the maincomponents of the ELI–NP infrastruc-ture. We thank the EU for funding theELI Preparatory Phase within the 7thFramework Programme.

References 1. European Strategy Forum on Reseach

Infrastructure (ESFRI), Roadmap forEuropean Research Infrastructure,Report of the Physical Sciences andEngineering, Roadmap Working Group,PSE-Report-Roadmap-WG-2006-en.

2. ELI http://www.extreme-light-infra-structure.eu/

3. http://www.eli-beams.eu/ 4. http://www.eli-hungary.hu/index–

EN.html 5. ELI-NP http://www.eli-np.ro/ 6. J. P. Chambaret, The Extreme Light

Infrastructure Project ELI and its Pro-totype APOLLON/ILE ‘‘the Associated

Laser Bottlenecks,’’ LEI Conference,Brasov, Romania, 16–21 October 2009.

7. F. V. Hartemann et al., Phys. Rev. STAB 8 (2005) 100702.

8. C. Barty et al., Development of MEGa-Ray technology at LLNL: http:/www.eli-np.ro/executive committee-meeting-april-12-13.php (2010).

9. W. J. Brown et al., Phys. Rev. ST AB 7(2004) 060702.

10. F. Albert et al., Opt. Lett. 35 (2010) 454. 11. E. Haseltine, http: //discovermagazine.

com /2002 /feb/cover 12. D. Habs et al., arXiv:1007.1251v3

[nucl-ex] 2010, accepted by Appl. Phys.B. DOI: 10.1007/S00340-010-4278-x.

13. K. L. Kratz, K. Farouqi, and B. Pfe-iffer, Prog. in Part. and Nucl. Phys. 59(2007) 147.

14. I. V. Panov and H.-Th. Janka, Astr.Astroph. 494 (2009) 829.

15. A. P. L. Robinson et al., Plasma Phys.Control. Fusion 51 (2009) 024004.

16. A. Henig et al., Phys. Rev. Lett. 103(2009) 245003.

17. A. I. Titow et al., J. Phys.G: Nucl.Part. Phys. 32 (2006) 1097.

18. H. A. Weidenmüller et al., Rev. of Mod.Phys. 81 (2009) 539 and G. E. Mitchellet al., Rev. of Mod. Phys. (2010) in press.

19. M. S. Dewey et al., Phys. Rev. C73(2006) 044303.

20. J. Schwinger, Phys. Rev. 82 (1951) 669. 21. D. Habs, P. Thirolf, N. Elkina, and H.

Ruhl, Brilliard hard. α-production ande+e–-creation in vacuum with ultra-highlaser fields: testing theoretical predic-tions a ELI-NP. Proceedings of thePIF2010 Conference at KEK, Tsukuba,Japan, November 24–26, 2010.

22. K. Homma, D. Habs, and T. Tajima,arXiv:1006.4553[quant-ph]2010.

23. D. Habs and U. Köster, arXiv-1008.5336v1[physics.med-ph]2010,accepted by Appl. Phys. B. DOI:10.1007/S00340-010-4278-1.

24. D. Habs et al., arXiv-1008.5324v1[nucl-ex]2010, accepted by Appl. Phys. B.DOI: 10.1007/S00340-010-4276-3.

25. P. G. Hansen, A. S. Jensen, and B.Jonson, Annu. Rev. Nucl. Part. Sci. 45(1995) 591.

26. T. Hayakawa et al., Nucl. Instr. Meth.A 621 (2010) 695.

DIETRICH HABS

LMU Munich

TOSHIKI TAJIMA

LMU Munich

VICTOR ZAMFIR

IFIN-HH Bucarest

impact and applications


Laboratory of Neutron Activation Analysis at the Nuclear Physics Institute of the ASCR, Rež

Introduction In addition to analytical methods

with ion and neutron beams describedin the previous issue of NuclearPhysics News [1], neutron activationanalysis (NAA) has been tradition-ally pursued at the Nuclear PhysicsInstitute (NPI). NAA as the mostimportant radioanalytical techniquefor determination of trace elements inbulk samples of various matrices hasbeen utilized at NPI since the end ofthe 1960s, after the advent of Gesemiconductor detectors for high-res-olution γ-ray spectrometry. In thisperiod, attention was paid especiallyto analysis of the materials of mineralorigin, for example, tektites [2], mete-orites [3], minerals, rocks, and lunarsamples (from the Apollo 11 and 12expeditions) [4]. The introduction ofnon-destructive, so-called instrumen-tal neutron activation analysis (INAA)opened the possibilities of applica-tion of this technique in many otherfields, namely environmental controland monitoring, biological, medical,nutritional, material, and archaeologi-cal research, in analytical qualityassurance, and so on. To be able toutilize the potential of NAA for analy-ses of various materials effectively,many technical advances and method-ological improvements have beenmade.

Technical Description of the Laboratory Facilities

Neutron irradiation is carried outin the LVR-15 research reactor of theNuclear Research Institute Rež, Plc.operated at 8–10 MW thermal power,in which thermal, epithermal and fast

neutron fluence rates of up to 7·1013 ncm−2, 7·1013 n cm−2, and 6·1013 n cm−2,respectively, are available in verticalchannels. One of these channels isequipped with a pneumatic transportsystem for short-time irradiation, inwhich polyethylene containers can beirradiated for 10 s–3 min with thetransport time of 3.5 s. In severalother channels long-time irradiationin Al cans can be carried out for sev-eral hours to several weeks. Bothshort- and long-time irradiation canbe performed in special containersmade of or inlaid with a 1-mm Cdshield to screen out thermal neutronsand to achieve selective activationwith epithermal neutrons (epithermalneutron activation analysis—ENAA)and/or fast neutrons (fast neutron

activation analysis—FNAA). Formeasurement of the induced activi-ties, the laboratory is equipped with aCanberra Genie 2000 γ-spectrometricsystem, which comprises severalcoaxial HPGe detectors with relativeefficiency in the range of 20 to 78%and FWHM resolution of 1.75 to 1.87keV for the 1332.5 keV photons of60Co, one planar HPGe detector withthe effective area of 500 mm2, thick-ness of 15 mm, FWHM resolution of550 eV at 122 keV, and one well-typeHPGe detector with the active volumeof 150 cm3, FWHM resolution of2.02 keV at 1332.5 keV, well dimen-sions 16 × 50 mm. For a dynamic cor-rection of the dead-time and pile-upeffects, Canberra 599 Loss Free Count-ing modules are used. To facilitate

Pre-irradiation chemical separation

Selective neutron irradiation (TNAA, ENAA, FNAA)

Alternative activation routes(e.g., PGNAA, PAA, CPAA)

Independent isotopic activation reactions and/or

activation reactions of same isotope

Alternative standards and standardisation methods

INAA, ENAA, FNAA RNAA

Alternative counting techniques Alternative radiochemical separations, yield determinations

Consistency checks Self-verified and/ or

cross-checked results

Figure 1. Block diagram of strategies for self-verification in NAA [7].



counting of large batches of solidsamples, two coaxial HPGe detectorsare equipped with a pneumatic samplechanger. Contamination-free samplepreparation is carried out at a cleanbench, which provides Class 10 work-ing environment. Ordinary chemicallaboratories, as well as radiochemicallaboratories with disposal systemsfor both solid and liquid radioactivewaste are integral parts of the labora-tory of neutron activation analysisat NPI.

Methodological Developments

Self-Verification Principle Among the many favorable fea-

tures of NAA [5], the possibility todetermine a particular element usingdifferent neutron induced reactionsof its isotopes is a very salient one,which has no analogy in other analyt-ical techniques. Since it forms thebasis for a unique ability to verifyanalytical data that NAA produces,this special property has been termedthe self-verification principle [6].Figure 1 shows the basic elements of

the self-verification principle inNAA. The primary source of theindependence of the analytical data isthe essentially isotopic nature ofNAA, that is, activation of differentisotopes of the same element, and thepossibility of using different, againessentially independent, isotopicnuclear reactions, such as (n, γ),(n,p), (n,α), (n,2n), (n,f) in NAA. Ithas been shown [6] that more than 25elements most frequently assayed inbiological and environmental matri-ces can be determined by at least twoindependent reactions giving gammaemitting radionuclides. Figure 2illustrates an example of self-verifi-cation of INAA results for Se inhuman red blood cells using twoindependent nuclear reactions74Se(n,γ)75Se and 76Se(n,γ)77mSe [7].In addition to the undoubted inde-pendence of analytical data providedby NAA using different isotopicreactions, other elements of indepen-dence exist in NAA methods. Inter-nally independent routes to analyticalinformation in NAA can be providedby several ways:

• using the different modes ofNAA non-destructive, instrumen-tal NAA (INAA) or radiochemicalNAA (RNAA)

• using selective activation withthermal, epithermal, and fast neu-trons (TNAA, ENAA, and FNAA,respectively)

• using selective measurement tech-niques (α-, γ-, and X-ray spec-trometry, Compton suppressioncounting in γ-ray spectrometry, γ-γor β-γ coincidence counting, β andCherenkov counting, and delayedneutron or fission track countingfor determination of fissile ele-ments and/or nuclides)

• using combinations of the above.

Other examples of various strategiesof the self-verification principle havebeen published elsewhere [7].

NAA as a Primary Method of Measurement

Due to a higher potential for accu-racy compared with other methods ofelemental analysis, especially for traceelement analysis, NAA has beendenoted for a long time as a “refer-ence, arbitrary, independent” method.However, only recently the case hasbeen made for NAA as a primarymethod to the Consultative Committeeon the Amount of Substance (CCQM)of the International Committee forWeights and Measures (CIPM) [8].Although the final recommendationsare not yet finalized, it appears thatCCQM has agreed to consider NAAas a primary method of measurement.This has been achieved because themethod satisfied the CCQM´s defini-tion that “a primary method of mea-surement is a method having thehighest metrological properties, whoseoperation can be completely describedand understood, for which a completeuncertainty statement can be writtendown in terms of SI units” [9, 10].

y = 0.9928x + 0.0162

R2 = 0.9381

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0.2 0.4 0.6 0.8 175Se, 264.7 keV, mg kg–1

77m

Se,

161

.9 k

eV, m

g k

g–1

Figure 2. Self-verification of INAAresults for Se in human red bloodcells using two independent nuclearreactions [7].

0

2

4

6

8

10

12

14

16

18

20

1350 1400 1450 1500 1550 1600

Co

un

ts p

er c

han

nel

Energy, keV

52V, 1434.1 keV

40K, 1460.8 keV

Figure 3. Section of γ-ray spectrum of aseparated vanadium fraction in RNAAof blood. The 52V peak corresponds to~50 pg·mL-1 of vanadium [12].



Two types of primary methods are dis-tinguished: (1) A primary directmethod: measures the value of anunknown without reference to a stan-dard of the same quantity and (2) Aprimary ratio method: measures thevalue of a ratio of an unknown to astandard of the same quantity; its oper-ation must be completely described bya measurement equation.

Obviously, NAA belongs to thelatter category and extends the list offormerly recognized potentially pri-mary methods of measurement, whichcomprise isotope dilution massspectrometry (IDMS), coulometry,gravimetry, titrimetry, and determina-tion of freezing point depression [10].The recognition of NAA as a primarymethod of measurement has furtheraccentuated its special positionamong other trace element analyticalmethod. The NAA laboratory at NPIhas contributed to this recognition byone of the very first design of quanti-fication of uncertainty in NAA [11].

Radiochemical NAA (RNAA) Ordinary INAA of complex

matrices may yield unsatisfactory

detection limits and/or uncertaintiesof trace elements of interest due tothe overwhelming activities of other

radionuclides formed on neutronactivation. There are various physi-cal means of improvements of detec-tion limits of elements, such asoptimization of irradiation, decayand counting times, use of selectiveactivation with thermal, epithermaland fast neutrons, use of specificcounting techniques, and so on,which has been described in detailelsewhere [12]. However, it has beendemonstrated that in cases where theinduced radionuclides of trace ele-ments are masked by matrix activity,radiochemical separation is very fre-quently the most effective means ofoptimization in NAA and yields thelowest detection limits and uncertain-ties, which are close to the theoreticalones [12]. Examples are given inTable 1 and Figure 3. Table 1 presents

Table 1. Comparison of uncertainties of ENAA and RNAA for low-level determination of iodine in identical food samples [12].

*Combined relative uncertainty in which all standard uncertainties exceptfor counting statistics are equal to ~3% and ~4% for ENAA and RNAA,respectively.

Sample

ENAA RNAA

ng·g-1 uc,r*, % ng·g-1 uc,r*, %

1 32 29.3 39 5.7

2 58 28.3 69 5.0

3 62 29.3 58 5.2

4 130 27.3 124 4.5

5 178 12.6 164 4.0

Table 2. Single-element RNAA procedures [7and refs. therein].

Element Nuclear reaction Sample decomposition Separation

Si 30Si(n,γ)31Si Alkaline-oxidative fusion with Na2O2 + NaOH

Distillation of SiF4

V 51V(n,γ)52V Pre-irradiation dry ashing in air followed by post-irradiation wet ashing in a mixture of H2SO4 + HNO3 + HClO4

Extraction with N-benzoyl-phenyl-hydroxylamine

Cr 50Cr(n,γ)51Cr Wet ashing in a mixture of HNO3 + HClO4

Extraction with tribenzylamine

Mn 55Mn(n,γ)56Mn Wet ashing in a mixture of HNO3 + HClO4

Precipitation of hydrated MnO2

I 127I(n,γ)128I Alkaline-oxidative fusion with Na2O2 + NaOH

Extraction of elementary I with CHCl3

Re 185Re(n,γ)186Re 187Re(n,γ)188Re

Microwave assisted wet ashing in a mixture of HNO3 + HF or alkaline-oxidative fusion with Na2O2 + NaOH

Extraction with tetraphenylarsonium chloride or methylethylketone or solid extraction with trioctyl-methylammonium chloride

Pt 198Pt(n,γ)199Pt→199Au Wet ashing in a mixture of HNO3 + HClO4

Precipitation of elementary Au with Se by ascorbic acid

Tl 203Tl(n,γ)204Tl 203Tl(n,2n)202Tl

Wet ashing in a mixture of HNO3 + HClO4 (+ HF)

Extraction with Na diethyldithiocarbamate



a comparison of uncertainties foriodine determination in biologicalsamples using ENAA and RNAA,while Figure 3 shows a result ofRNAA for determination of vana-dium in blood, in which very selec-tive radiochemical separation yieldedthe vanadium peak at virtually zerobackground. For this reason, a num-ber of RNAA procedures were devel-oped at NPI to be able to fullyexploit the possibilities of NAA fordetermination of extremely low lev-els of elements. These procedures arebriefly summarized in Tables 2 and3. Thus, the laboratory of NAA atNPI became one of the world-leadinginstitutions, where RNAA is avail-able for determination of elements attrace and ultratrace levels in variousmatrices, which find many interdisci-plinary applications.

Main Research Activities The INAA and RNAA procedures

developed are utilized in a wide vari-ety of research activities, which areperformed in close collaboration withCzech institutions and those abroad.INAA has been used in environmentalcontrol and monitoring, especially inanalysis of ambient air aerosols,aerosols originating from combustionprocesses, and aerosols from occupa-tional settings. This technique is beingincreasingly used in geo- and cosmo-chemical research to study the com-position and origin of rocks,sediments, tektites [13] and meteor-ites [14]. One of these studies resultedin a new theory of moldavite forma-tion [13]. A combination of short- andlong-time irradiation and countingwith coaxial and planar HPGe detec-tors using suitable decay and countingtimes yields information on contentsof up to 35 major, minor, and traceelements. If RNAA is also used to

determine Rb and Cs and almost allrare earth elements (which provideinformation about the origin andevolution of a rock or a meteorite),and instrumental photon activationanalysis (IPAA) is employed fordetermination of some elements thatcannot be assayed with INAA,contents of 42 elements can bedetermined in this type of samples[14]. A similarly large number of ele-ments were also determined withINAA in an archaeological study onthe origin of sandstone blocks usedfor the construction of Khmer templesin Angkor, Cambodia. The combina-tion of INAA and RNAA proved to beuseful in occupational and environ-mental health studies concerningevaluation of workers’ exposure inmachining, assembling and weldingof stainless steel constructions [15],and exposure of workers of a vana-dium pentoxide production plant andthat of general population living in thevicinity of the plant. The determina-tion of vanadium in blood and urineof control subjects in the aforemen-tioned studies by RNAA yielded

improvements of our knowledgeabout normal, baseline levels in occu-pationally non-exposed population[16]. This is an example of vanadiumdetermination at the ultratrace ele-ment level (~50 pg·mL−1), which canhardly be achieved by any other ana-lytical technique. Similarly low levelsand/or amounts of elements in biolog-ical materials were also determinedby RNAA in biomedical studies con-cerning dynamics of trace elementconcentrations during neurodegenera-tive processes in the brain, such asAlzheimer’s disease, studied in brainsof mutant mice [17], or in studyingthe pharmacokinetics of cisplatin, anantitumor drug. In nutritional studies,INAA and RNAA were employed toassess the transfer of pollutants intoagricultural crops and foodstuffsgrown in the vicinity of a phosphatefertilizer production plant [18], whileENAA and RNAA were used forassessment of iodine intake fromAsian diet samples [19]. Trace ele-ment determination in mushrooms byINAA and ENAA is at the borderlineof purely mycological and nutritional

Table 3. Multi-element RNAA procedures [7 and refs. therein].

Element (nuclide) Sample decomposition Separation

Rare earth elements Alkaline-oxidative fusion with Na2O2 + NaOH

Precipitation with oxalic acid

Cu, As, Mo, Cd, Sb Wet ashing in a mixture ofH2SO4 + HNO3 + H2O2

Extraction with Zn diethyldithiocarbamate

Co, Ni (58Co) Wet ashing in a mixture of HNO3 + HClO4

Ion exchange chromatography using Dowex 2 × 8

Hg, Se Microwave assisted wet ashing in HNO3

Extraction with Ni diethyldithiocarbamate and precipitation of elemental Se with ascorbic acid

I, Mn Alkaline-oxidative fusion with Na2O2 + NaOH

Extraction of elementary I with CHCl3 and precipitation of hydrated MnO2 or Mn extraction with Na diethyldithiocarbamate



research (if edible mushrooms areconcerned), and can also be used inenvironmental monitoring due to aspecial ability of some mushroomspecies to accumulate certain ele-ments from their environment. Notonly elements, but also some long-lived radionuclides can be measuredwith NAA for environmental moni-toring. An example is assay of 129I, along lived fission product with half-life of 15.7·106 years, with NAAemploying a combination of pre- andpost-irradiation separation of iodineto study the 129I distribution in theBaltic Sea [20] and in thyroids fromUkraine and Denmark [21]. In theview of a special potential of NAA foraccuracy compared with other traceelement analytical techniques, NAA

has been used at NPI in chemicalmetrology, for quality assurance andin the preparation of reference materi-als (RM) of chemical composition along time before the method has beenrecognized as a primary method ofmeasurement. INAA and RNAA pro-cedures were employed for homoge-neity tests and certification of elementconcentrations in RM prepared bynational and international bodies.Table 4 shows NPI activities in thepreparation of RM with various matri-ces achieved in co-operation with themost important RM producers, suchas the U.S, National Institute ofStandards and Technology (NIST),Institute for Reference Materials andMeasurements (IRMM—the EuropeanCommission Joint Research Centre),

and the International Atomic EnergyAgency (IAEA), Vienna. Table 5compares RNAA results of certifica-tion analyses of ultratrace levels of Vand Ni in the recently prepared NISTSRM-1577c Bovine Liver achieved atNPI with the NIST certified values.NAA has also many times helped in

Table 4. NPI activities in the preparation of reference materials of world-leading producers.

RM code Producer Method Activity

IAEA A-11 Milk Powder, IAEA H-4 Animal Muscle, IAEA A-13 Freeze Dried Animal Blood, IAEA H-8 Horse Kidney, IAEA H-9 Mixed Human Diet

IAEA, Vienna RNAA New data on Cu and Mn

Single cell green algae RMs with managed levels of heavy metals IAEA-391, IAEA-392, IAEA-393

IAEA, Vienna INAA, RNAA Certification analyses for up to 22 elements

IAEA Reference Air Filters (RAF)-I, IAEA Reference Air Filters-II

IAEA, Vienna INAA Preparation of RAF, homogeneity testing and certification analyses for up to 35 elements, evaluation of the certification campaign

IRMM-530 Al-0.1% Au alloy IRMM, Geel INAA New data on Au content

IRMM-540R, IRMM-541 Uranium-doped glass IRMM, Geel INAA Certification analyses for uranium

NIST SRM-1515 Apple Leaves, NIST SRM-1515 Peach Leaves NIST SRM-1573a Tomato Leaves

U.S. NIST, Gaithersburg INAA, RNAA Certification analyses for 28 elements

NIST SRM-1570a Spinach Leaves U.S. NIST, Gaithersburg INAA, RNAA Certification analyses for 20 elements

NIST SRM-2783 Air Particulate on Filter Media U.S. NIST, Gaithersburg INAA Certification analyses for 23 elements

NIST SRM-1648 Urban Particulate Matter U.S. NIST, Gaithersburg INAA New data for V and Mn

NIST SRM-1577c Bovine Liver U.S. NIST, Gaithersburg RNAA Certification analyses for V and Ni

Table 5. Comparison of RNAA results for V and Ni with NIST certified values for NIST SRM-1577cBovine Liver [22].

aexpanded uncertainties with coverage factor of 2 are given.

Element, ng·g-1 V Ni

NPI resulta 8.4 ± 1.0 44.0 ± 6.4

NIST valuea 8.17 ± 0.66 44.5 ± 9.2



resolving of discrepant analytical dataand there are also several examplesthat the consistent application of NAAadvantages lead to the corrections oforiginally biased certified values. TheNAA results helped in improvingassigned values of Cu and Mn in IAEARM A-11 Milk Powder [7]. While thiscase concerned the correction of dataobtained in an open intercomparison,in another case the NAA resultsobtained at NPI differed from NISTvalues for Mn and V in NIST SRM-1648 Urban Particulate Matter [7].This finding has led to a change of theoriginal NIST values to new ones asgiven in Table 6. It is noteworthy thatthis was only the second case wheredata for environmental and/or biologi-cal RM obtained outside NIST has ledto a correction of the NIST certifiedvalues of element contents.

It can be concluded that despite ofthe fast development of other traceelement analytical techniques, suchas atomic absorption and fluores-cence spectrometry, and mass spec-trometry, NAA is indispensable forsolving special analytical tasks inmany interdisciplinary applications.

This concerns especially the caseswhere a large number of elements isto be determined or where determina-tion of very low elements levels witha low uncertainty is required.

References 1. J. Dobeš, Nucl. Phy. News 20 (2010) 5. 2. J. Kuncí0, J. Benada, Z. Randa, and M.

Vobecký, J. Radioanal. Chem. 5(1970) 369.

3. M. Vobecký, J. Frána, Z. Randa, J.Benada, and J. Kuncí0: Radiochem.Radioanal. Lett. 6 (1971) 237.

4. M. Vobecký, J. Frána, J. Bauer, Z.Randa, J. Benada, and J. Kuncí0, Pro-ceedings of the Second Lunar ScienceConference, vol. 2, The M.I.T. Press,Geochim. Cosmochim. Acta, Suppl. 2(1971) 1291.

5. A. R. Byrne, Fresenius J. Anal. Chem.345 (1993) 144.

6. A. R. Byrne and J. Ku1era, Proc. Int.Symp. on Harmonization of HealthRelated Environmental Measure-ments Using Nuclear and IsotopicTechniques, Hyderabad, India, 4–7November 1996, IAEA Vienna, 1997,paper IAEA-SM-344/8, 223–238.

7. J. Ku1era, J. Radioanal. Nucl. Chem.273 (2007) 273.

8. R. R. Greenberg, J. Radioanal. Nucl.Chem., 278 (2008) 231.

9. T. J. Quinn, Metrologia 36 (2009) 65. 10. Report of the 4th Meeting (February

1998) of CCQM, BIPM, Sevres,France, ISBN 92-822-2164-4, 71(February 1999).

11. J. Ku1era, P. Bode, and V. Štepánek, J.Radioanal. Nucl. Chem. 245 (2000) 115.

12. J. Ku1era and R. Zeisler, J. Radioanal.Nucl. Chem. 262 (2004) 255.

13. Z. Randa, J. Mizera, J. Frána, and J.Ku8era, Meteoritics and PlanetarySci. 43 (2008) 461.

14. Z. Randa, J. Ku1era, and L. Soukal, J.Radioanal. Nucl. Chem. 257 (2003) 257.

15. J. Ku1era, V. Bencko, J. Tejral, L.Borská, L. Soukal, and Z. Randa, J.Radioanal. Nucl. Chem. 259 (2004) 7.

16. E. Sabbioni, J. Ku1era, and R. Pietra,and O. Vesterberg, Sci. Total. Environ.188 (1996) 49.

17. J. Bäurle, J. Ku1era, S. Frischmut, M.Lambert, and K. Kranda, BrainPathol. 19 (2009) 586.

18. J. Ku1era, J. Mizera, Z. Randa, and M.Vávrová, J. Radioanal. Nucl. Chem.271 (2007) 581.

19. J. Ku1era, G. V. Iyengar, Z. Randa,and R. M. Parr, J. Radioanal. Nucl.Chem. 259 (2004) 505.

20. X. L. Hou, H. Dahlsgaard, S. P.Nielsen, and J. Ku1era, J. Environ.Radioactivity 61 (2002) 331.

21. X. L. Hou, A. F. Malenchenko, J.Ku1era, H. Dahlgaard, and S. P.Nielsen, Sci. Total. Environ. 302(2003) 63.

22. R. Zeisler, B. E. Tomlin, K. E. Mur-phy, and J. Ku1era, J. Radioanal.Nucl. Chem. 282 (2009) 69.

23. U.S. NIST Certificate of Analysis, http://ts.nist.gov/measurementservices/refer-encematerials/index.cfm

JAN KUCERA

Nuclear Physics Instituteof the Academy of Sciences

of the Czech Republic

Table 6. Comparison of old and new values for Mn and V in NIST SRM-1648 Urban Particulate Matter.

aNIST values with uncertainty are certified; noncertified values are in parenthesis.

Element, mg·g-1

Original NIST valuesa [23] NPI results [7]

New NIST valuesa [23]

Mn (860) 768 ± 18 786 ± 17

V 140 ± 3 128 ± 4 127 ± 7

meeting reports


Report on the FINUSTAR3 Conference

The 3rd International Conferenceon Frontiers In Nuclear STructure,Astrophysics, and Reactions(FINUSTAR 3) was held on theisland of Rhodes, Greece from August23–27, 2010. The venue was theRodos Palace Hotel on the north-east-ern coast of Rhodes, 2 km north of thecapital city Rhodos. It was organizedby the Institute of Nuclear Physics(INP) of the National Center for Sci-entific Research (NCSR) “Demokri-tos” (Athens, Greece) and theDepartment of Physics of the Univer-sity of Jyväskylä (JYFL, Finland).

FINUSTAR3 was the third in aseries of international conferencespreviously held in 2005 in the isle ofKos, Greece and in 2007 in AgiosNikolaos, Crete, Greece. Just like theprevious ones, this conference cov-ered a wide spectrum of research

activities in nuclear structure, nuclearastrophysics, and nuclear reactionsthat due to common instrumentationand research facilities have been over-lapping strongly over the last years:

• Nuclear structure at the extremes. • Collective phenomena and phase

transitions in nuclei. • Exotic excitations. • Synthesis and structure of the

heaviest elements. • Nuclear masses and ground state

properties. • Ab-initio calculations and the shell

model. • Mean field theories, cluster mod-

els, and molecular dynamics. • Scattering and reaction dynamics

at low and intermediate energies. • Nuclear reactions off stability and

indirect methods. • Neutrinos in nuclear astrophysics

and astro-particle physics. • Nuclear astrophysics (Big-Bang

nucleosynthesis, s-, r-, and p-process,& nuclide production).

• Radioactive and exotic relativisticbeams.

• Facilities and instrumentation forthe future.

The conference was attended by 150physicists with a fair representation ofall the major nuclear physics laborato-ries. There were a total of 131 contribu-tions, 79 of them given as oral (20

invited talks and 10 invited contribu-tions) and 52 as poster presentations.Ninety-eight of them were based onexperimental and 33 on theoreticalresults. They were of excellent quality,also reporting on fresh new data andresults and provoking lively discussions.

The conference was supported bythe EU-FP7 project “Center ofExcellence in Low-energy Ion-BeamResearch and Applications—LIBRA”of the Tandem Accelerator Labora-tory, INP, NCSR “Demokritos.”

The best poster presentation intheory and experiment were electedby a committee consisting of mem-bers of the international advisorycommittee and awarded a prize of 500euro. The winners were John Daouti-dis (ULB, Brussels) and GulfemSusoy (Istanbul University), respec-tively. An additional excellent posterprize, not accompanied with money,was awarded to Nassima Adimi(CENBG, Bordeaux) (see Figure).

The proceedings of FINUSTAR3will be published in AIP ConferenceProceedings Series.

SOTIRIOS V. HARISSOPULOS

Tandem Accelerator LaboratoryInstitute of Nuclear Physics, NCSR

“Demokritos”

RAUNO JULIN

Department of PhysicsUniversity of Jyväskylä

Nuclear Structure 2010 The conference “Nuclear Structure

2010” (NS2010) was hosted byLawrence Berkeley National Labora-tory, 9–13 August 2010. This was the

thirteenth in this series of conferences,which are hosted once every two yearsby the North American National Labo-ratories. More than 140 people attended

from over 50 institutions representing20 different nations around the world.Nuclear structure physics remains anexciting, international affair.

The winners of the FINUSTAR3 posterprize: Nassima Adimi (CENBG,Bordeaux), Gulfem Susoy (IstanbulUniversity), and John Daoutidis (ULB,Brussels).

meeting reports


Berkeley, with its long history as ahome of progressive ideas and cutting-edge intellectual research, provided aperfect back-drop to the conference thatplayed out at the beautiful Clark-KerrCampus on the edge of the city. Theprogram ranged over the latest researchand developments in nuclear structurephysics which covered diverse topicsconcerning the properties of nuclei atthe extremes of isospin, mass, angularmomentum, and excitation energy. Inkeeping with the tradition of the confer-ence, only a handful of speakers wereinvited and most of the talks wereselected from submitted abstracts. Thisresulted in a vibrant program withmany young speakers, some givingtheir first talk at a major internationalconference, presenting the very latestresearch from their labs and universi-ties. The program, talks, and many pho-tos are available at the conferencewebsite: http://www.lbl.gov/nsd/con-ferences/nuclearstructure2010/.

The conference started with a spe-cial session devoted to halo nuclei, dis-covered twenty-five years ago atBerkeley by Tanihata and collaborators.Halo nuclei, which have spatiallyextended wavefunctions arising from adecoupling between the weakly bound

valence nucleons and the core, are nowa major research focus at many radioac-tive-ion beam facilities and provide adramatic example of the type of newphenomena we hope to discover as wepush to the edges of nuclear stability.Later sessions provided a snapshot ofthe newest results and latest ideas acrossthe entire ambit of the field: from dis-cussions of the decay of proton-rich iso-topes to the shell evolution in nucleiwith extreme neutron excess; from themicroscopic understanding of the light-est systems to the observation of super-heavy elements (including the latestelement added to the periodic table, asreported by Krzysztof Rykaczewski ofOak Ridge National Laboratory onbehalf of the collaboration that recentlydiscovered element-117 at Dubna).

The final session was devoted tothe latest experimental facilities beingbuilt in the United States and we heardabout the progress toward the FRIBaccelerator (Facility for Rare IsotopeBeams to be hosted by Michigan StateUniversity) and the GRETINAgamma-ray tracking array (currentlybeing assembled at Lawrence BerkeleyNational Laboratory). In the nearfuture, it is clear these experimentaladvances, along with similar facilities

being constructed elsewhere in theworld, will create an exciting period ofexploration and discovery in the fieldof nuclear structure.

In conclusion, I should like to para-phrase some comments from one of thegreat figures in the field (those attend-ing the meeting should know to whom Irefer), made at an earlier incarnation ofthis conference, also held in Berkeley,but repeated again by Mark Riley ofFlorida State University in his NS2010summary talk. “I have the distinctimpression that our subject is in the bestpossible shape. Mother Nature contin-ues to shower us with her bounties andwe remain continually amazed by thecomplexity and elegance of nuclei. Weare enjoying ourselves, being very cre-ative, and our techniques are powerfuland beautiful. We are continually find-ing new phenomena and the theories weuse have tremendous intellectual bite.”The truth of these words was clearlydemonstrated at Nuclear Structure2010. I look forward to the next confer-ence in the series and I wish the localorganizers of NS2012 at ArgonneNational Laboratory the very best.

RODERICK CLARK

Lawrence Berkeley Laboratory

news and views


International Agreement on the FAIR International Accelerator facility

Nine Countries are Involved in One of the World’s Largest Research Projects in Darmstadt, Germany

Nine countries signed the interna-tional agreement on the constructionof the accelerator facility FAIR(Facility for Antiproton and IonResearch) on 4 October in Wies-baden, Germany (see Figure). FAIRwill be located at the GSI HelmholtzCenter for Heavy Ion Research inDarmstadt, Germany. Signing theagreement were science ministersand state secretaries from Finland,France, Germany, India, Poland,Romania, Russia, Slovenia, and Swe-den. The countries that could not yetjoin because of their internal ratifica-tion procedures (France, Poland, andSlovenia) are expected to do sowithin the next year. China, SaudiArabia, Spain, and the United King-dom are also planning to contributeto FAIR.

Immediately after the signing,FAIR GmbH was established as acompany. The first shareholders areGermany, Russia, India, Romania,and the Swedish–Finnish consortium.In its first session, the council of thecompany appointed Boris Sharkov asscientific managing director andSimone Richter as administrativemanaging director. Beatrix Vierkorn-Rudolph was appointed as the firstchair of the FAIR council.

FAIR will be one of the largestresearch projects and most sophisti-cated accelerator centers worldwide.The international agreement has nowcleared the way for its realization.Germany will bear roughly three-quar-ters of the total costs of approx. €1billion. Roughly 3,000 scientists frommore than 40 countries are alreadyworking on the planning of the experi-ment and accelerator facilities. FAIRwill generate antiproton and ion beamsof a previously unparalleled intensityand quality. When completed, FAIRwill comprise eight ring accelerators

of up to 1,100 meters in circumfer-ence, two linear accelerators, andaround 3.5 kilometers of beam pipes.The existing GSI accelerators willserve as preaccelerators for the newfacility. FAIR will make it possible toconduct a wider range of experimentsthan ever before, enabling scientistsfrom all over the world to gain newinsights into the structure of matterand the evolution of the universe sincethe Big Bang.

INGO PETER

GSI Darmstadt

Representatives of the signatory countries in Schloss Biebrich, Wiesbaden(Photo: G. Otto, GSI).

news and views


The G.N. Flerov Prize is Awarded for Studies of Exotic Nuclei Near the Drip-Lines

The G.N. Flerov prize for 2009is awarded to Sidney Gales, Domin-ique Guillemaud-Mueller, and YuriPenionzhkevich for outstandingresults achieved in the study of theproperties of exotic nuclei near thenucleon drip-line (see figure).

The G.N. Flerov prize was estab-lished in 1992 in accordance withthe resolution of the 71st Session ofthe Scientific Council of the JointInstitute for Nuclear Research(Dubna) in memory of the eminentphysicist Georgy Nikolaevich Flerov(1913–1990).

The prize is awarded for the con-tributions in the field of nuclearphysics related to Flerov’s interestsconnected with the experimentalheavy ion physics including the syn-thesis of heavy and exotic nucleiusing ion beams of stable and radio-active isotopes, studies of nuclearreactions, acceleration technology,and applied research.

RUMIANA KALPAKCHIEVA

JINR Dubna G.N. Flerov prize winners, from left to right: Sidney Gales andYuri Penionzhkevich.

calendar


April 3–8 Eilat, Israel. Nuclear Physics in

Astrophysics 5 http://www.weizmann.ac.il/

conferences/NPAS/

April 27–May 1Vancouver, Canada. 10th Interna-

tional Conference on Low EnergyAntiproton Physics (LEAP 2011)

http://leap2011.triumf.ca/

May 2–6Saint Malo, France. FUSION11http://fusionl1.ganil.tr/

May 17–20Newport News, Virginia, USA. The

18th International Workshop on thePhysics of Excited Nucleons (NSTAR2011)

http://conferences.jlab.org/nstar2011/index.html

May 31–June 3 Leuven, Belgium. Advances in

Radioactive Isotope Science (ARIS –2011)

http://iks32.fys.kuleuven.be/aris/

June 6–10 Bordeaux, France. Fourth Interna-

tional Conference on Proton-emittingNuclei PROCON2011

http://www.cenbg.in2p3.fr/PROCON2011/

June 12–17 New London, NH, USA. Gordon

Research Conference on NuclearChemistry

http://www.grc.org/programs.aspx?year=2011&program=nuchem

June 12–18Crete, Greece. 11th International

Conference on Applications of NuclearTechniques

http://www.crete11.org/

June 27–July 2Constanta, Romania. Advanced

Many-Body and Statistical methodsin Mesoscopic Systems

http://www.theory.nipne.ro/donstanta-meso2011

August 8–12 Manchester, UK. Rutherford

Centennial Conference on NuclearPhysics

http://rutherford.iopconfs.org/

September 5–9 Vienna, Austria. International

Conference on Exotic Atoms andRelated Topics - EXA2011

http://www.oeaw.ac.at/smi/research/talks-events/exotic-atoms/exa-11/

September 11–18Piaski, Poland. XXXII Mazurian

Lakes Conference on Physicshttp://www.mazurian.fuw.edu.pl/

October 11–15 Kyoto, Japan. Yukawa Interna-

tional Seminar “Frontier Issues inPhysics of Exotic Nuclei” (YKIS2011)

http://www2.yukawa.kyoto-u.ac.jp/~ykis2011/ykis/index.html

November 23–28Hanoi, Vietnam. International

Symposium on Physics of UnstableNuclei 2011 (ISPUN11)

http://www.inst.gov.vn/ispun11/

2012 March 1–3

Phillip Island, Victoria, AustraliaAstronomy with Radioactivities VII

http://cspa.monash.edu.au/awr7/

March 10–11 Lund, Sweden HIE-ISOLDE Spec-

trometer Workshop http://indico.cern.ch/conference

Display.py?confId=116915

May 31 – June 3 Agios Nikolaos, Crete, Greece 4th

International Conference on ChaoticModeling, Simulation and Applica-tions (CHAOS2011)

http://www.cmsim.org/

June 6–9 Ghent, Belgium Second International

Conference on Advancements in NuclearInstrumentation, Measurement Methodsand their Applications - ANIMMA

http://www.animma.org/

June 13–17 Stockholm, Sweden Nordic Con-

ference on Nuclear Physics 2011 http://www.nuclear.kth.se/

NCNP2011/Home.html

June 27–30 Padova, Italy EGAN 2011 Workshop http://egan.lnl.infn.it/egan2011.html

June 30–July 2 RIKEN Tokyo, Japan Joint Inter-

national Symposium on Frontier ofgamma-ray spectroscopy (gamma11)

http://www.cns.s.u-tokyo.ac.jp/gamma11/

July 4–10 St. Petersburg, Russia Isomers in

Nuclear and Interdisciplinary ResearchMeeting (INIR-2011)

http://onlinereg.ru/inir2011

September 4–9 San Sebastián, Spain 2nd Interna-

tional Particle Accelerator Confer-ence IPAC2011

http://www.ipac2011.org/

September 16–24 Erice, Sicily, Italy Erice School

2011 “From Quarks and Gluons toHadrons and Nuclei”

http://crunch.ikp.physik.tu-darmstadt.de/erice/

September 17–21 Bucharest, Romania. European Nuc-

lear Physics Conference EuNP C2012 http://www.ifin.ro/eunpc2012/

More information available in the Calendar of Events on the NuPECC website: http://www.nupecc.org/

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