Regione Piemonte - Bando Converging technologies 2007 ...personalpages.to.infn.it/~staiano/web-neuART/proposta_finale.pdf · study of textile, argillaceous and ligneous artworks,

Regione Piemonte - Bando Convergingtechnologies 2007 - Piedmont RegionConverging technologies call 2007

neutron and x-ray tomography and imaging for cultural heritage

ACRONYM: neuARTSECTOR: Nanotechnology - new materials - ICTABSTRACT: Modern Cultural Heritage restoration techniques and in general the need ofa deep understanding of the fine structure of objects of cultural significance requirepowerful and complementary analysis, and have a particular relevance in our region sincethe foundation of the Centro Conservazione e Restauro “La Venaria Reale”. This centrerepresents a relevant cultural enterprise in our region, being both a restoration and aformation centre for cultural heritage restorers at university level. It is certainly strategic forCCR development to promote collaborations with other research institutes, universities,and private companies of Piemonte in the framework of cultural heritage object analysisand description. We focus in the present proposal on the importance of computed tomography andimaging as invaluable tools for the description and understanding, prior restoration, ofcultural heritage objects, not only with the more conventional X-ray tomography, but alsousing neutron computed tomography (CT) and imaging. The use of neutrons in the cultural heritage field has received considerable attention in thepast years. Neutrons are particularly suited in art objects analysis and imaging due to theircapability to penetrate thick layers of materials, and they are very interesting when used inconjunction with X-ray imaging, since the absorption of photons and neutrons are verydifferent for various materials (metals for instance are almost neutron transparent contraryto photons, while H2 rich materials are opaque to neutrons). Neutron computedtomography can be obtained, in analogy with X-ray CT, by measuring the attenuation of aneutron beam passing through the sample to be analyzed. By rotating the object exposedto the neutron beam and by using custom image reconstruction algorithms, it is possibleto form 3D virtual maps of the object. The similarity in the two imaging approaches makespossible the planning of a CT device which can be used for both type of analysis. Cold and thermal neutron sources are generally nuclear reactors designed for researchpurposes, like the two Italian plants of University of Pavia and ENEA-Roma. In the presentproposal however we would use a small and compact high intensity Deuterium-Deuteriumfusion source with a full solid angle integrated fluence of up to 10**12n/sec that will beinstalled in the existing bunker of the Experimental Physics Department of the TorinoUniversity. The involved groups have a ten year experience in these kinds of neutronsources, in design and construction of moderators to obtain thermal neutrons and inneutron detection. In parallel to neutron and X-ray computed tomography, Prompt GammaActivation Analysis will be exploited, using resonance absorption properties of cold

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Title

GENERAL INFORMATIONS

neutrons. Many elements, commonly found in cultural heritage objects, have neutronabsorption resonance properties, and their cross sections are known in detail. This allowsrelative abundance determination of neutron sensitive elements, which is often essentialfor traceability of archaeological artifacts and artistic object components. The project will be completed building a 2D x-y plotter for high resolution X-rayradiography of large scale paintings (up to 3x4m) to be installed in the CentroConservazione e Restauro “La Venaria Reale”. This device will furnish the Venaria Centrewith an imaging instrument of unprecedented potential for applications, both for therestoration and the study of ancient paintings. The present proposal is the result of the synergic concentration of efforts of the TorinoINFN and Experimental Physics Department groups that have accumulated aconsiderable experience in neutron physics, material characterization using low energy X-ray and particle beam, high energy physics large scale experiments and particle detectorsdesign and assembly.DURATION (months): 36TECHNICAL SCIENTIFIC OBJECTIVES: The main goal of this project is the constructionof a combined system for neutron and X-ray computed tomography and imaging, focusedon Cultural Heritage analysis in collaboration with the Centro Conservazione e Restauro“La Venaria Reale”. To our knowledge this will be the first combined system devoted to thiskind of application in Italy. Neutron Tomography is a useful technique for testing objects of artistic andarchaeological interest, given the fact that thermal neutrons are non invasive and canpenetrate thick layers of the sample. The unique possibility to operate a neutron source isprovided by the presence in the underground area of the Department of Physics of theUniversity of Torino of a dedicated, certified shielded bunker, where in former times the“Turin Syncrotron” was hosted. Present technology allows the construction of compact highintensity neutron sources, based on RF-driven ion source impinging few hundreds KeVaccelerated D plasma on a D o T target, where neutrons are produced by fusion process.The limited size of the neutron source makes feasible the planning of a in-housetomographic device which, having the ability to rotate the target and displace the detectorindependently, allows neutron tomography on samples of unprecedented dimensions(when compared to fixed neutron sources deriving from nuclear reactors). As a complement to neutron computed tomography (CT) we plan to develop elementanalysis techniques like Prompt Gamma Activation Analysis (PGAA), a technique whichallows the detection of the elemental distribution in the sample. The neutron CT system will be set in parallel to a X-ray CT system, allowingcomplementary imaging of the same sample and thus enriching the analysis potential ofthe project. The experience of the groups involved in this proposal is crucial in the knowledge and useof neutron and X-ray sources and detectors. These type of detectors are developments ofHigh Energy Physics experimental programs, and research efforts will be invested indetector optimization according to the required performance. The proponent groups haveexperience in gas detector and silicon detector systems, detector families widely used inneutron and X-ray imaging. In particular a group participating to the project has developeda detecting system based on silicon microstrip detectors and single-photon countingelectronics optimized for dual-energy X-ray imaging. This system has been successfullyused both for medical imaging tests and for mapping the distribution of particular chemicalelements (e.g Zn, Cd) in art paintings. In parallel to detector know-how, the INFN Torino group, with its staff of engineers andtechnicians, will allow a full custom and optimized integration of the detection system in afully numerical controlled computed tomography device, designed from scratch to be usedboth for neutron and X-ray imaging, and another dedicated tool for 2D X-ray imaging oflarge scale art paintings (3x5m) to be installed in the Centro di Conservazione e Restauro

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di Venaria Reale. This device will provide the Venaria Centre with an imaging instrumentof unprecedented potential both for the restoration and the study of ancient paintings.STATE OF THE ART: Tomography allows investigations of the microscopic innerstructure of large samples; it is based on the measurement of the attenuation of aradiation beam passing through an object and is done by taking images at differentorientations of the sample and reconstructing off-line all data in a virtual 3D object. Many kinds of particles and radiations can be used to obtain important information aboutthe structure, density, composition, etc. of the analyzed objects, but two complementarymethods are X-ray and neutron tomography, since the absorption of photons andneutrons are very different for various materials: metals for instance are almost neutrontransparent (as opposed to photons), while H2 rich materials are opaque to neutrons. Since X-ray can easily penetrate through centimeters of light materials (liquids andorganic materials), they are utilized in many fields including medicine, cultural heritage,and industrial applications. In cultural heritage X-ray CT and imaging is mainly used in thestudy of textile, argillaceous and ligneous artworks, but also small metal and stone piecesare analyzed; the importance of this diagnostic tool can be understood for example in theligneous artworks analysis were X-ray CT can provide information about cracks, worm-eaten areas, woods density, annual rings, nails, etc. At present, small X-ray tubes up to 450 KeV and Linac up to few tens of MeV are used assources; the minimum spatial resolution achievable is about 1 micron. In Italy someindustries (for examples Fiat Avio) have their own system, but there is no researchinstitution that provides high-level services as in other countries (e.g. EMPA, Switzerland). Contrary to the photon case, a neutron beam can transmit through centimeters of metalbut it is easily attenuated by small amounts of light elements like hydrogen, boron andlithium. For this reason neutron tomography is an unique tool for non-destructive testingwith applications in cultural heritage analysis, industry, material science and various otherfields. The investigation of moisture and corrosion, the detection of explosives andadhesive connections and the inspection of defects in nuclear fuel or in thick metallicsamples are examples where neutron can be utilized favorably. Neutron tomography is obtained using beams of thermal or cold neutron from nuclearreactors and so must be considered as stationary. In fact, until now, only reactors cangive fluxes with sufficient intensity for a tomography (between 10**5 and 10**9 n/cm**2 s),but the beam collimation allows to obtain a maximum beam area of 30x30 cm and so toanalyze only small objects. In Italy there are only two of these reactors located at theUniversity of Pavia and ENEA-Roma. In the past years some small neutron generators have been developed (e.g. in Berkeley),but until now they have only been used for medical applications (BNCT). They are highintensity Deuterium-Deuterium fusion sources with a full solid angle integrated fluence ofup to 10**12 n/sec. After moderation and collimation the obtained flux is sufficient toproduce a neutron-image in few seconds. Using a last generation CCD camera with2048x2048 pixels it takes about 4 s to readout the entire array. The minimum spatialresolution achievable is about 0.2mm, and it degrades linearly with the distance betweenthe sample and the conversion screen. The best example of currently existing activity in this field in Europe (Milano and Romafrom Italy), is represented by the ANCIENT CHARM initiative, which is the result of acollaboration between 10 universities, research laboratories, and museum institutionsacross Europe, and is now a EU funded ADVENTURE project, under the New andEmerging Science and Technology (NEST) program of FP6. The central goal of ANCIENTCHARM is to develop an imaging technique based on Neutron Resonant Capturetogether with complementary neutron diffraction, and transmission-based imagingtechniques.POTENTIAL IMPACT: The present proposal would entail significant advances in thetechnical and scientific know-how acquired by the research partners (INFN Torino and the

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University of Torino) in a new field, i.e. non-destructive characterization techniques forcultural heritage, opening up new possibilities for national and international scientificcollaborations, participation in international calls and funding initiatives, and providing anenriched base for the existing collaboration with the Centro di Conservazione e Restauro“La Venaria Reale” for teaching and courses. Also, it would provide an opportunity toreconvert highly-specialized INFN structures and facilities to new tasks. For the industrial participants (SEPA SpA Torino and NEKHEM Srl Torino), the projectcould bring considerable advantages related to the acquisition of new knowledge andexpertise, expanding the working area of interest from scintillation detectors forradioactivity measurements in transit goods to that of neutron sources and detectors forvarious applications (SEPA), and from imaging for medical applications to imaging in thefield of cultural heritage (NEKHEM). The neutron radiography technology to be developedin the project can indeed be easily applied both in the characterization of cultural heritageartefacts as in the verification of structural integrity of large scale parts used in varioussectors of industry. Thus, the project could possibly open up new possibilities and marketportions for SEPA and NEKHEM in Piemonte and abroad. The main objective of the project is however to provide the Centro di Conservazione eRestauro di Venaria Reale with technology, structures and know-how in the field of X-rayand neutron radiography (currently available only in the ENEA-Roma plant), thus possiblyrealizing the ambitious goal of allowing the Venaria Centre to compete with the two mostimportant centres for cultural heritage conservation in Italy, namely Rome and Florence.The impact for the Venaria Centre, for the city of Venaria and for the Region of Piemontewould thus be considerable in terms of visibility and prestige. Also, the new techniquesdeveloped in the project could be applied to characterize the state of conservation ofmany medium or large scale artefacts currently residing in the Museums of Torino andPiemonte.DESCRIPTION OF THE RESOURCES: The Istituto Nazionale di Fisica Nucleare,operates in close collaboration with departments of Fisica of the University of Torino,sharing infrastructures, manpower, laboratories and knowledge. For this reason bothinstitutes are to be considered as proponents and act in full coordination. The Sezione di Torino of Istituto Nazionale di Fisica Nucleare, is organized in researchstaff members (physicists and engineers), who actively work in experimental activitiescentrally managed by national scientific committees of the institute, and local serviceswhich grant administrative and technical support. The technical support is organized inspecialized divisions, with permanent technical staff. In Torino INFN can support activitiesthrough its electronic laboratory, where electronics and integrated electronic projects canbe fully developed, through the mechanical workshop, a 3000 m**2 atelier, wheremechanical engineers and designers can develop projects and produce executabledrawings of objects which can be built in the workshop by dedicated personnel working onnumerical controlled milling machines of various types and dimensions, and finally by acomputing centre, which grants full supports for operating local servers and complexcomputing farms designed, assembled and operated to meet the important computationalrequirements of the experimental groups. The present project will heavily make use of the Torino INFN resources both in terms ofthe use of the infrastructures related to the described laboratories, and in terms ofmanpower provided by technical staff of the administration, electronics, mechanical andcomputing local services. In particular, a sophisticated large scale, high precisionmotorized x-y gantry, designed and built by INFN Torino for the construction of the muondetectors of the CMS experiment at CERN (43 Drift Tubes chambers of 4,2x2,5m withmore that 50000 readout channels), will be modified and adapted to be operated as X-raysource and detector support for large area art painting X-ray imaging. The dual X-raysilicon detector has also been developed by INFN for the NA50 experiment and hasalready been successfully used in art painting imaging.

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Moreover University of Torino will provide the laboratories, with associated equipments,where the scientific apparatus will be assembled and operated, and, mostly important, theshielded bunker where all nuclear devices, the neutron source and the X-ray source willbe operated in full conformity with the existing law. This area is a unique structure thatwas used until 1986 for the "Turin Synchrotron", a formerly pioneering electronaccelerator machine. The area has been recently renovated and is available forinstallation of a stationary nuclear device as, for instance, a neutron source. University willalso be of crucial relevance in the formation of students and fellows who will join thisproject. It should be underlined that co-proponents of this project, already active in thefield of neutron analysis, are also teaching university courses in the Venaria Centre, bothin the Restoration School and in the Corso di Laurea in Scienza e Tecnologia per i BeniCulturali of the Science Faculty of the Torino University.ORGANIZATION: The collaboration is formed by five partners, one proponent (IstitutoNazionale di Fisica Nucleare Sez. di Torino) and one additional proponent (Universita’ diTorino), two co-proponents (SEPA S.p.A. and NEKHEM S.r.l.) and one additional subject(Centro Conservazione e Restauro “La Venarla Reale”). The project, planned over 3 yearsactivity, is organized in 10 Work Packages. The weight of each partner in each WP ismodulated over the expertise and know how which will be invested. The Dipartimento diFisica Sperimentale of University of Torino will have a leading role in WP1 (neutronsource) and WP3 (neutron detector), given the fact that the group has very good anddocumented experience in these fields. INFN, thanks to the experience on designconstruction and commissioning of large apparatuses and related electronics, willcoordinate WP6 (mechanical system for X-ray and neutron Computed Tomography), WP8(2D Art Painting Radiography) WP9 (K-Threshold Art Painting Imaging), and WP10 (WPmanagement). WP2 (Design and manufacturing of thermal/cold column) and WP5 (X-RayTomography) will have important contributions from both INFN and University of Torino.Finally WP4 will be covered by co-proponent SEPA S.p.A. (Photon Gamma ActivationAnalysis Detection and Neutron Resonant Capture Analysis), a firm with good expertise inphoton detector applications, while NEKHEM S.r.l., a computing SME with skills inmedical imaging algorithms development, will take responsibility and organize WP7 (X-Ray and neutron tomography and imaging. Centro Conservazione e Restauro “La Venaria Reale”, is the final user of all project’s WP’sand directly participates to WP3,5,8,9. It’s activity will be fundamental in giving feedbackand validation to all CT imaging instruments and algorithms developed. The overall project organization, will be managed through WP10, which will cover generalcoordination tasks and will constantly monitor progresses of the activities of the WP’s,ensuring that the project will meet its objectives within budget and scheduled timescales.This WP will routinely make reports both to funding and collaborating agencies and willdrive dissemination initiatives. All administrative work will be managed and controlledwithin this WP. The consortium will be coordinated by the project manager with regular meetings and adedicated web site will be used to archive all informations and documents shared by allpartners.DISSEMINATION: The collaboration with the Centro Conservazione e Restauro "LaVenaria Reale" will play a central role in the dissemination of the scientific results ofthe present project. We expect that the analysis of artistic objects of different types, bothin terms of tomography and radiography inspections and in terms of analysis of thematerials, will allow a deeper understanding of the artistic samples. This will turn either ineasier and better restoration when needed, or in traceability or authentication of art objectcomponents or archaeological sample. The dissemination of the results of the analysis ofartistic objects will therefore proceed through parallel streams. The Centro Conservazionee Restauro "La Venaria Reale" will provide the best visibility to the project.From the appearing of first results to the end of the project CCR will organize and

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patronize meetings and workshops about diagnostic and scientific aspects involved,paying always the right attention to preserve any information connected to eventualpatents. Relevant events will be also widely communicated to press agencies. Starting from the important flux and presence of artistic samples in its restorationlaboratories, CCR could easily organize workshops focused on manufacts of particularartistic and historical relevance. In parallel to this, scientific results coming from the research of the proponents will bepresented in national and international conferences and workshops, where theachievements in the neutron and X-ray tomography of cultural heritage objects will bepresented. Dissemination will also go through publication of scientific results oninternational reviews. Publication of scientific results will be strongly encouraged andpursued during the full activity of the project, but all dissemination initiatives will always bepreviously discussed within the full group (proponents, co-proponents and adjunctivesubjects). As for CCR care will be taken in preserving informations related to potentialpatents. An essential tool to maximize internal communication between the partners (passwordprotected) and information to external world will be the creation and maintaining of a website dedicated to this project. Within the web site we will create a database to be used asa general repository of all actions taken by any of the partners in the diffusion of theresults of the project (thus including presentations to workshops and conferences,published articles and posters, press releases, and patents). The group of partners will also enhance dissemination of general informations on theproject also outside the cultural heritage and scientific communities, since we expect thatthe technology described in this project will have important potential applications also inother fields of relevant importance in Piedmont territory. This will be done not only throughthe web site, but also by directly investigating possible applications in other fields, throughactive analysis of reviews and conference proceedings and direct communication withexternal subjects dealing with applications possibly related to our analysis capabilities.DIFFUSION OF THE RESULTS: As specified above, the main aim of the project is toexploit existing know-how and resources from the INFN and University research partnersto provide the Venaria Conservation and Restoration Centre with innovative facilities foreffective characterization of cultural heritage artefacts, with the support of industrialresearch partners who will be involved in the development of the detecting and dataprocessing stages. Therefore, the interest in the exploitation and diffusion of the projectresults differs for the various partners: INFN and UniTo have interest in communicatingthe scientifically original results of the project in journal publications and conferencecontributions; the Industrial partners have interest in acquiring the know-how for thedescribed characterization techniques for future exploitation in consulting services orapplications in other fields, possibly leading to patents for specific instruments ortechniques developed in the course of the project; the Venaria Centre has mainly interestin acting as end-user in this case, acquiring innovative technology and expertise for theuse of an additional characterization technique for cultural heritage objects, thus reachinga prominent position among its competitors. Therefore, the participants have subscribed arather general preliminary agreement on Intellectual Property Rights (IPR), basicallystating that any original knowledge emerging from the project will be attributed to allparticipants involved in its acquisition and circulated exclusively among them, with thepossibility of publishing scientific results and/or exploiting technical innovations forcommercial purposes, e.g. patents. There is also the opportunity of involving venturecapital at a later stage, e.g. in a continuation of the project, possibly leading to a Startupcompany exploiting the know-how and specialist instrumentation developed in the project.In this case, the IPR settlement would be modified accordingly, with specific agreementsbetween the participants.ISSUES ETHICS: We do not envisage ethical aspects to be relevant to the present

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project.ATS (more than one coproponent): YesASSOCIATED KEYWORDS: 4.6.12 Neutron physics ,4.3.11.3 Software development,2.1.3.3 Art works restoration ,2.1.3.2 Art works preservation ,4.3.1 3 D modelling ,4.6.8.1Radiation physics ASSOCIATED ACTIVITY CODES: 3.4 New areas not covered in the specific programme,3.1.1 Long-term interdisciplinary research into understanding phenomena, masteringprocesses and developing research tools ,3.1.5 Applications in areas such as health andmedical systems, chemistry, energy, optics, food and environment FREE KEYWORDS: art,neutron,tomography,X-ray,digital-imagingFREE ACTIVITY CODES: nuclear techniques applied to cultural heritageFINANCING TOTAL: 6529858FINANCING TOTAL PROPONENT: 3899748FINANCING TOTAL COPROPONENT: 2007760

NUMBER: 1TITLE: Installation and characterization of neutron generatorRESPONSIBLE: LORENZO VISCASTARTING MONTH: 1ENDING MONTH: 36OBJECTIVES: At present neutron tomography can be realized by means of thermaland/or cold neutrons mainly produced by nuclear reactor. The project proposes to use acompact neutron source developed by the Plasma and Ion Source Technology Group atLawrence Berkeley National Laboratory. This device is based on D-D fusion reaction,producing 2.45 MeV neutrons. It can provide neutron flux in excess of the current state ofthe art D-D neutron generators and more than most commercial D-T neutron generators.It operates without pre-loaded target or radioactive tritium gas. Safe and reliable long-lifeoperation is typical feature of this D-D generator. Because of the high neutron fluence produced by the neutron source, great attention hasto be pointed on protection from the ionising radiation produced. For this reason the D-Dsource will be installed in the bunker located at the Experimental Physics Dept. of TorinoUniversity. This facility was realized around 1960 to host a particle accelerator used fornuclear physics experiments and it has been recently modified in such a way to besuitable for installing new irradiation facilities. The D-D neutron generator is based on a unique co-axial design, which maximizes thetarget area in a compact outer dimensions of the generator. The dimensions areapproximately 45 cm in diameter and 60 cm in height. The large target area enables oneto operate at high beam power, with efficient cooling thus yielding high neutron fluxes.The most powerful prototype available from LBNL is designed to operate 300 mA ofdeuterium beam current at 160 kV of acceleration voltage. This beam current andacceleration voltage yields a D-D neutron flux of >10^11 s-1. In order to run the device a high vacuum has to be reached inside the plasma chamber;then the deuterium gas is flowed inside the chamber and plasma is generated by RF(13.56 MHz) discharge method. The produced ions are subsequently diffused toward theextraction apertures of the plasma chamber and accelerated in the gap between theplasma generator and the target cylinder. When ions are accelerated they impinge on a titanium coated aluminum target, ions areimplanted in it to about 1 micro meter depth. Due to the elevated temperature of the

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Work Package: Installation and characterization of neutron generator

implanted target area, the deuterium atoms diffuse in the metal matrix. The maximumreaction efficiency is reached when these diffused deuterium atoms are reacting with in-coming deuterium ions at very close to the target surface. An electrostatic secondaryelectron filter structure is employed between plasma chamber and target in order to stopthe secondary electrons accelerating back to the plasma generator, thus generatingexcess heat in the plasma generator walls and lowering the available HV power supplycurrent for the ion beam. An additional secondary electron filter arrangement is made bypermanent magnets, located into the aluminum target cylinder. A magnetic shieldingmade of carbon steel is wrapped around the target to eliminate any stray magnetic fieldstowards the target, that might lead to HV spark-downs. The target cylinder-structure issupported by a Al2O3 cylinder, which functions also as a high voltage insulator. The aim of this task is to optimise the functional parameters of the neutron source in sucha way to maximize the neutron flux. In particular the activity consist on: 1) investigation and optimisation of the deuterium plasma generation; 2) study and manufacturing of the cooling system; 3) optimisation of the vacuum system; 4) monitoring of: functional parameters, material characteristics, material stress underhigh neutron irradiation, materials activation; 5) beam testing and installation and tests of commercial beam monitoring system; 6) installation of interlock systems both for radioprotection and instrumentation safety.DESCRIPTION: 1) An important feature of the RF-induction discharge is that it generateshigh fraction of atomic ion species from molecular gases. Another feature of the RF-induction discharge is its ability to generate high plasma. An RF-matching network is usedto match the plasma and antenna impedance to the output impedance of the RF-amplifierand co-axial transmission line. One of the activity inside of this task is the optimization of the matching network tomaximize the transferred power from the RF generator to the antenna. Correct impedancematching allows to obtain high density plasma for high extractable ion current fromrelatively small discharge volume. Different tests about the antenna life have to be taken on. This high flux generator is aunique prototype and there are not so clear indications about the antenna wear underhigh usage stress. 2) Titanium has the property to form stable chemical compounds (metal hydrides) whencombined with hydrogen or its isotopes while aluminium is characterized by a lowdiffusivity for deuterium. During the first few minutes of operation the target will be''loaded'' with deuterium atoms. During this phase of operation the neutron yield isconstantly increasing. When equilibrium condition is reached and the target is saturatedthe neutron yield saturates to a level typical for the current and voltage used. If the targettemperature increases to much the equilibrium is lost and the neutron flux decreases. A close loop cooling system has to be realized: deionising water has to be cooled andtemperature controlled by a chiller before to reach the target, the vacuum system, theantenna and the RF network. Different tests about the link between the target cooling and the neutron beam have to betaken on in such a way to determine the correct temperature of the target to maintain astable neutron beam. 3) The vacuum system is based on a turbo molecular pump, backed by a rotary vaneroughing pump. Without gas load the vacuum in the target chamber will reach 10^-8 mbarlevel. Good vacuum level has to be maintained during the deuterium gas injection insidethe plasma chamber. Better vacuum condition supports the deuterium ion beam inreaching the target. Tests about the level of both gas flow and vacuum are needed to

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obtain high plasma density and good neutron beam performance. Periodic checks of thevacuum will control possible leakages in the system mainly due to gaskets damages. 4) It is necessary to realize a cross checking monitoring system of different functionalparameters (vacuum level, plasma density, target temperature, cooling flow) to have acomplete control of the neutron generator and to prevent possible risks derived fromfunctional failures of the service apparatus. Periodic disassemblies of part of the systemare necessary to asses possible components’ damages and activation due to the highradiation stress level. 5) Characterization of the beam is necessary because this kind of neutron generator hasnever worked at so high emission rate. Neutron spectra of the bare generator has to bemeasured for realising the moderator column. This measured has to be taken on usingdifferent methods to cover all the energy range. Neutron fluence has to be measured infunction of voltage and current of the HV generator, plasma density and targettemperature. After that correct commercial beam monitoring system has to be bought,installed and tested. 6) Italian regulations require some features for the use of neutron source generating aneutron beam >10^7 n/s. Class A neutron sources have to be used ensuring theprotection from ionizing radiation to workers and population. Doors microswitches have tobe installed to control the area access when the neutron beam is on. Special keys systemto switch on the neutron generator is needed. Neutron and gamma monitor for theambient dose measures have to be installed in such a way to take under control radiationlevels.ATTENDED RESULTS: - A unique neutron beam facility will be realized using a noncommercial fusion generator. When the neutron generator will be installed and all testswill be taken over a stable and well characterized 2,5 MeV neutron flux will be available tobe used for epithermal, thermal and cold neutron production. Neutrons could be used fordifferent kinds of application from materials analysis to medical physics. -Titanium is the most efficient metal hydrides for neutron generation. In steady-state, thedeuterium concentrations are believed to reach certain saturation values, which dependon the target temperature. In the theoretical calculation it is assumed that the saturationconcentration are constant over the particle range, and that the target thickness is largerthan the particle range. For a deuteron beam of current I and energy E composed ofmonoatomic species the total number of neutrons produced per second can be computedusing the integral form of the thick-target yield equation. When the machine and thecontrol and beam monitoring systems will be installed, we will be able to compare thecalculated neutron yield per current unit in Ti target as a function of the beam energycurrent density and target temperature. Deliverables: 1) design and acquisition of the necessary material and instrumentation: month 8; 2) completion of neutron source installation: month 14; 3) characterization of the bare neutron source: month 24; 4) report on neutron source performances: month 24; 5) report on neutron thermal column charachteristics: month 30; 6) report on the whole system performances: month 36.

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AGENCY PARTICIPANT: Dipartimento di Fisica SperimentaleSTARTING MONTH PEOPLE ACTIVITIES: 1ENDING MONTH PEOPLE ACTIVITIES: 36PEOPLE/MONTHS ACTIVITIES FOR PARTICIPANT: 24

AGENCY PARTICIPANT: Istituto Nazionale di Fisica NucleareSTARTING MONTH PEOPLE ACTIVITIES: 1ENDING MONTH PEOPLE ACTIVITIES: 36PEOPLE/MONTHS ACTIVITIES FOR PARTICIPANT: 33

AGENCY PARTICIPANT: SEPA S.p.A.STARTING MONTH PEOPLE ACTIVITIES: 1ENDING MONTH PEOPLE ACTIVITIES: 36PEOPLE/MONTHS ACTIVITIES FOR PARTICIPANT: 3

NUMBER: 2TITLE: Design and manufacturing of thermal/cold columnRESPONSIBLE: ALBA ZANINISTARTING MONTH: 1ENDING MONTH: 36OBJECTIVES: The neutron generator, characterized by a coaxial design, is based on D–Dreaction producing 2.45MeV and it is designed to provide a neutron yield >10^11 s-1.While the neutron energy distribution, for deuterium beam energies < 160 keV, spreadbetween 2.9 MeV and 2.1 MeV, the angular distribution is isotropic. In order to performneutron tomography these particles need to be moderate to lower energies and thisrequires the construction of a Beam Shaping Assembly (BSA). While the primary purposeof this assembly is to shift the neutron energy spectrum to lower energies maintainingadequate beam flux, several different components, such as moderator, reflector, gammashielding and delimiter, are needed to make proper use of all neutrons and to properlytailor many aspects of the beam. The optimisation of BSA consists in the choice ofappropriate materials, thicknesses and shapes in order to get the best neutron spectrumat the beam exit. Concerning the angular distribution of the beam, the best option seemsto be a quasi-parallel beam with a L/D-ratio (that is a measure of the beam collimation,where D is the diameter of an aperture and L the distance between aperture andmeasuring position) as high as achievable. In this way, no geometrical distortion occursand the spatial resolution should be limited only by the properties of the detector device. At present thermal neutrons are mainly used for tomography, but there are also some

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Participant to the Work Package: Installation and characterization of neutrongenerator

TOTAL PEOPLE/MONTHS OF ACTIVITY Installation and characterization ofneutron generator: 60

Work Package: Design and manufacturing of thermal/cold column

options with cold neutrons. The main reason to use cold neutrons is to improve the imagecontrast. Far from resonances, the cross-section for neutron capture is inverselyproportional to the neutron velocity, or using the particle-wave duality, is proportional to itswavelength. Thus comparing thermal (1.8 angström) and cold neutrons (5.5 angström), theimage contrast obtained with cold neutrons is generally about the cube of that withthermal neutrons. The objective of WP2 is to: 1) study by means of simulation code a thermal column suitable to perform neutrontomography on different objects; 2) design and manufacturing thermal column; 3) perform test, compare simulation results with measurements and characterize thethermal neutron field; 4) investigate, design and manufacturing a new column to produce cold neutron toimprove the image contrast; 5) perform test on the cold column, compare simulation results with measurements andcharacterize the neutron field.DESCRIPTION: The Monte Carlo code MCNP-4C will be used to model the neutronsource, to study the BSA and to simulate the neutron and photon transport in the column.The most suitable materials to moderate and reflect neutrons will be investigated througha careful analysis of materials macroscopic cross-sections (elastic scattering, inelasticscattering, absorption), obtained from the ENDF/ B-VI cross-sections libraries. Moreoverattention will be paid to the material activation in order to meet the radioprotectionrequirements. The activation analysis will be carried out with FISPACT (NEA-1564) code.It is a complete tool for the calculation of activation in materials exposed to neutronswhere the neutron energy does not exceed 20 MeV. The part of the code consist of theinventory code FISPACT-2003, the EAF-2001, EAF-2003 and the FENDL-2 data libraries.EAF contains cross section data of neutron-induced reactions for energies between 1.0E-5 eV and 20 MeV. The primary job of the BSA is to provide the moderation of the neutron beam to thermal orcold energies by interaction with moderator materials. It is important to choose materialsthat cause the rapid loss of energy to the desired energy range without overmoderation orloss of neutrons, moreover the material thickness should also be as little as possible todecrease the geometric attenuation of the beam. A reflector is needed to maximize thetotal neutron flux to the beam exit window. It should be thick enough to provide adequatereflection but it should also not significantly absorb useful neutrons. The optimization ofthe reflector is very important especially with a co-axial neutron source, where neutronsare not preferentially directed towards the exit window. A gamma shielding is required ifgamma-ray contamination from the BSA components is determined to be significant. Itconsists of a thin plate at the edge of moderator or it covers the exit window at the edge ofthe delimiter. Moreover, depending on the shielding requirements of the treatment room,neutron or gamma shielding (or both) also may be added around the entire BSA. Thegamma component in the moderated neutron beam, coming from the compact generator,is very poor compared to that one in the reactor, where photons produced by secondaryreactions in the moderator are added to the gamma created in the reactor core. A beam delimiter must be provided to absorb neutrons that are not aimed at the targetvolume, it should be cone-shape to channel neutrons to the target and be thick enough toprovide a good beam directionality. Different beam delimiter will be designed in order tochange easily the dimension of the neutron field (from 1x1 cm^2 to 20x20 cm^2)according to the experimental set-up. The beams will be compared through the assessment of free beam parameters such as:

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- thermal and/or cold neutron flux (> 1 E5 cm-2 s-1). - fast neutron contamination and photon contamination as low as possible, - beam collimation as high as possible. An important parameter for the tomography is the L/D ratio; it is a measure of the beamcollimation, where D is the diameter of an aperture and L the distance between apertureand measuring position. The larger the L/D ratio the better is the beam collimation. Theresolution is equal to the geometrical blur b=d/(L/D) where d is the distance betweenobject and detector screen. The L/D ratio can be increased to values of about 500 and the spatial resolution improvesto up to 200 micrometers. When the simulation step will be completed the columns realization will start. Test will berealized on each component and measurements will be compared always with thesimulation data. The final step consists in the complete characterization of the neutron field and in theinvestigation of the performance of the electronic devices and sensors used in theexperimental set up, under operative conditions.ATTENDED RESULTS: By the careful analysis of materials macroscopic cross-sections itis expected to select as good moderator materials: graphite, polyethylene, PMMA andheavy water. Concerning reflector materials C, Pb and Bi should effectively reflectneutrons back to the exit window, while a gamma shielding (made of Pb or Bi) shouldabsorb efficiently residual gammas. By means of MCNP-4c code a detailed simulation of the neutron source will be providedand different configurations (BSA) of the thermal column will be realized in order tooptimise the neutron beam at the collimator aperture. The thermal column will be manufactured following the optimized design and a completecharacterization of the beam will be provided. The new column will have a modularstructure in order to modify the beam according to the experimental set-up and it will beequipped with different collimator to change beam dimensions. A feasibility study of the cold column will be completed and following the same procedureexplained above the column will be manufactured following the optimized design andcharacterized. Deliverables: 1) design of the thermal column and acquisition of the necessary materials: month 15; 2) completion of thermal column: month 21; 3) completion of thermal column installation: month 27; 4) report on feasibility of a cold neutron column: month 30; 5) completion of thermal column optimization: month 30; 6) report on the whole system performances: month 36.

AGENCY PARTICIPANT: Istituto Nazionale di Fisica NucleareSTARTING MONTH PEOPLE ACTIVITIES: 1ENDING MONTH PEOPLE ACTIVITIES: 36

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Participant to the Work Package: Design and manufacturing of thermal/coldcolumn

PEOPLE/MONTHS ACTIVITIES FOR PARTICIPANT: 30


NUMBER: 3TITLE: Neutron detection and tomographyRESPONSIBLE: VINCENZO MONACOSTARTING MONTH: 1ENDING MONTH: 36OBJECTIVES: The main objective of this work package is to obtain an apparatus forComputed axial Tomography (CT) using thermal neutron on objects of interest in the fieldof cultural heritage. Being the neutron source developed in WP1 and WP2, this WP will befocused on neutron detection and on the assemblage of the whole system. Thermal or cold neutron tomography provide within a relative short time (from few minutesto few hours) a three-dimensional inside view of thick objects with spatial resolution downto 100 micrometers, in the case of few centimetre objects. Similar in principle to X-ray CT,the neutron tomography technique is based on the measurement of the attenuation of aneutron beam passing through an object. For a computed neutron tomography,two–dimensional (2D) transmission images of the sample taken from different view anglesare required, whereas the quality of the tomography depends strongly on the number ofimages from different view angles. Therefore the experimental setup for neutron tomography consists of the neutron source(mainly thermal neutron, but cold neutrons are also used) with a collimator (developed inWP1 e WP2), a rotary table for the rotation of the object (developed in WP6), a properdetector and a motion control system that synchronizes the rotary table and the detector.The common arrangement is a fixed beam line and a stationary detector, whereas thesample is rotated between them on a turn table. In this way, the necessary projections inorder to define a 3D map of the object are obtained (of the order of few hundred). The detection principle is the following: the neutron beam penetrating the sample isattenuated according to the sample material and geometry and reaches the neutronsensitive scintillator screen, where each detected neutron triggers a photon cascade. Thelight emitted by the scintillator is reflected to the CCD-camera by a mirror. This detectordesign allows to place the camera out of the direct neutron beam to protect the chip fromradiation damage. The detection system of the camera is read out by the computer. After exposure the computer sends a trigger signal to the rotary table, the sample is rotated of adefined angle and the next exposure starts automatically. In the past years, severaltechniques in digital imaging were successfully applied providing high sensitivity detectorswith important performances regarding their dynamic range and linearity. This holdsmainly for imaging plates and detectors based on CCD cameras with a scintillator screen

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TOTAL PEOPLE/MONTHS OF ACTIVITY Design and manufacturing ofthermal/cold column: 69

Work Package: Neutron detection and tomography

as primary neutron-to-light converter. Other methods are not yet completely optimised forneutron imaging (amorphous silicon arrays, micro-strip gas counters), but have a highpotential as detectors in radiography and in neutron scattering experiments as well. The final goal of this WP will be met through the following phases: 1) study, design and acquisition of the necessary material and instrumentation (12months); 2) construction and characterization of the detectors (6 months); 3) detector test using a commercial neutron class B source (6 months); 4) integration of the mechanical structures (WP 6) with the source and detector,alignment, calibration and tests with the acquisition and control software developed bySEPA (2 months); 5) detector test using a collimated class A neutron source (6 months); 6) system optimization and verification of 3D reconstruction software developed in WP 7by means of a number of tomographies on reference objects with different compositionsand dimensions (2 months); 7) system validation with CT scans on cultural heritage artefacts from public and privatemuseum collections (2 months).DESCRIPTION: The first phase consists in the study and design of the tomographicsystem to be assembled. Here, innovative solutions for the detector will be evaluated. Theneutron-to-visible-light converter usually consists of a 420 µm-thick ZnS layer doped with aCu, Al, Au and Ag blend with specified minimum resolution of 80 µm and homogeneity of±5.0%. Neutrons passing through the sample and arriving in the scintillator create alphaparticles by reaction with 6Li and the alpha particles produce blue light scintillation byreaction with ZnS. The scintillation light is peaked at 540nm and is reflected out of thebeam path at 45° or 90° by a silver-free mirror, to limit the radiation damage to the CCD.The distribution of the scintillations is imaged on the CCD array by means of a standardobjective lens or various lenses, to improve the spatial resolution of the image, especiallyfor small samples. In some cases, for thermal neutrons, the screen is made ofGd2O2S:Tb(Eu). Screens with different phosphor loading are manufactured and usedwith respect to different thermal neutron spectra of the source to optimise detectionefficiency and spatial resolution. A composite screen made of a silicon organic resin andembedded Gd2O2S:Tb(Eu) is used for fast neutron imaging. The CCD will be mounted ona vertical translation stage in order to accommodate different fields of view. A lead glassplaced between the objective and the mirror will protect the CCD chip from gamma raysemitted by the mirror and the converter. Finally, the camera will be covered on its sides bytiles of 6LiF polymers and lead bricks to shield it against neutrons and gamma rays. Towork in low neutron flux regime, a high efficiency detection system will be designed inorder to perform at least one tomography within one working day. The camera will benitrogen-cooled to reduce dark current, which is extremely important for long exposuretimes caused by the low neutron flux to gain a better signal to noise ratio. The mainrequirements for the mirror will be: a high reflectivity (95%) of the light emitted by thescintillator, generation of as few gamma-rays as possible and no lasting activation of thematerials composing the mirror. In the second and third phases the detector will be constructed and characterized using acommercial neutron class B source with a neutron flux few order of magnitude lower thanthe flux from the main source that will be developed in WP1 and WP2. Tests performedwith materials of various compositions and thicknesses will be important to optimize thedetector and to reduce the noise. The fourth phase will consist in the integration of the detector with the mechanicalstructure (WP 5 and WP 6) that has few components that are common with X-Ray CT.The software for the movement of the mechanical parts developed for X-Ray CT will beintegrated with the acquisition system of the neutron image by means of a CCD camera.

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In the fifth phase the thermal neutron flux obtained in WP2 from the main source will beused to obtain the first neutron images. The whole system will be checked in a fixedconfiguration. In this phase, it is foreseen that optimal measurement parameters will bedefined, such as the distance between the source, the detector, and the measured object,the neutron current and exposure time (which needs to be adjusted according to thephysical characteristics and dimensions of the object under analysis). Also in this phasetests will be performed with materials of various compositions and thicknesses. The sixth phase will be devoted to the first actual neutron tomography tests on referenceobjects. These will be fundamental to evaluate the functionality of the whole system. Atthe end of this phase, the whole structure will be ready to perform measurements onobjects of interest in the field of cultural heritage. In the final phase, system validation will be carried out on works of art from public andprivate museum collections.ATTENDED RESULTS: At present neutron tomography can be realized by means ofthermal and/or cold neutrons mainly produced by nuclear reactor. The main expectedresult of this WP is to obtain an innovative instrument for CT neutron scans on large scaleobjects or high-resolution scans on small objects using a compact D-D fusion reactionneutron source. The apparatus will be coupled to the X-Ray tomography systemdeveloped in WP 5. The number of analysis techniques available to cultural heritage researchers is constantlygrowing, but so is the demand for non-invasive methods to unveil the secrets hiddeninside archaeological objects. The information output from neutron CT should be uniqueand not available by other routine archaeometric tools. The samples that can be analyzedare hardly accessible by other diagnostic techniques like, for example, solid compositeobjects with complex structure but simple raw materials: casts containing a core, jewellerywith inlays and multi-layered objects (coins, belts, iron swords in an organic - wood andleather - sheath with metal fittings, fibulas). The specific advantage of neutrons compared to X-rays is their high interaction probabilitywith hydrogen and the lower attenuation in several heavy elements which are “black” for X-rays (e.g. lead, bismuth, uranium). This gives the justification for using neutrons forspecial applications where X-rays must fail even if neutron imaging is more expensive anddemanding. Moreover it will be possible to use the neutron CT developed in various other fields: spaceindustry, nuclear industry, geology, biology, dentistry, etc. The investigation of moistureand corrosion, the detection of explosives and adhesive connections and the inspection ofdefects in nuclear fuel or in thick metallic samples are examples where neutron can beutilised favourably. Deliverables. 1) design and acquisition of the necessary material and instrumentation: month 12; 2) delivery of detector system: month 18; 3) report on detector performaces using radiation sources: month 18; 4) report on detector performaces using class B neutron source: month 24; 5) delivery of neutron CT mechanical structure, including software controls: month 26; 6) report on detector performaces using class A neutron source: month 32; 7) report on the whole system performances: month 34; 8) report on first neutron CT on cultural heritage artifact: month 36.

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Participant to the Work Package: Neutron detection and tomography



AGENCY PARTICIPANT: FONDAZIONE CENTRO PER LA CONSERVAZIONE E ILRESTAURO DEI BENI CULTURALI "LA VENARIA REALE"STARTING MONTH PEOPLE ACTIVITIES: 24ENDING MONTH PEOPLE ACTIVITIES: 36PEOPLE/MONTHS ACTIVITIES FOR PARTICIPANT: 7


NUMBER: 4TITLE: Prompt Gamma Activation AnalysisRESPONSIBLE: EDOARDO DETOMASTARTING MONTH: 1ENDING MONTH: 36OBJECTIVES: The main objective of this WP is the construction of an apparatus for thedetection of gamma rays generated from the interaction of a neutron beam with thesample. The aim is to detect the gamma rays generated from neutron capture by atomicnuclei produced in sub-nanosecond time intervals (PGAA: Prompt Gamma ActivationAnalysis). The gamma rays are characteristic of the nucleus that has emitted them, andtherefore the energy detection of the latter allows the identification of the chemicalelements composing the sample under investigation. The sensitivity depends on thechemical element and is particularly high in the case of light elements like hydrogen,boron or nitrogen. The determination of the chemical composition is very important in many fields: in culturalheritage, to be able to determine chemical composition without the need to extractsamples is of fundamental importance, as it allows specific work on an object withoutdamaging it. Some examples of this are the identification of the constituent material ofobjects present inside sealed amphorae, or the composition of glues or fillers used toconsolidate wooden statues, or the determination of the material used for the soldering of

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TOTAL PEOPLE/MONTHS OF ACTIVITY Neutron detection and tomography:106

Work Package: Prompt Gamma Activation Analysis

metal statues. Currently, this technique has been primarily developed in research laboratories where anuclear reactor is present, allowing to have thermal or cold neutrons with sufficient fluxesto carry out this type of analysis (between 10^7 and 10^9 n/cm2 s). Usually the structuresfor this type of analysis are optimized for small samples (below 1 g.) and allow thedetermination of the sample composition with great accuracy, which is variable with theinvolved elements, but can reach above 10 ppb (10^-8). To obtain this kind of precision,often dedicated chambers are used in proximity of the outlet of the neutron flux, to reducethe neutron path in air to a minimum. In these chambers there is vacuum or He is fixed toreduce neutron scattering and gamma ray capture by air. Cultural heritage artefacts areusually quite large and do not allow this type of analysis, unless some sort of sample isextracted, which deteriorates the object under investigation. On the other hand, often it isnot necessary to obtain such high resolutions, because the material can be identified andone can obtain a good initial estimate of the composition. The aim is therefore to assemble two instruments that use the same detection system.The first, to be coupled to the neutron tomography, would allow the identification of theconstituent materials of the object under investigation (which can be quite large) with alimited precision, but sufficient for initial aims. The second would require the developmentof a dedicated analysis chamber, allowing to carry out measurements to determine thecomposition of small samples with great sensitivity (useful in the field of cultural heritagefor dating and determination of the origin of samples). The main goal of this WP will be attained by subdividing its development in variousphases: 1) design of the detection apparatus with choice of the detectors (12 months); 2) construction of the apparatus, of the detector shielding, of the detecting structure andpreparation of the management software; detector calibration with calibration sources (10months); 3) test using a class B neutron generator (flux< 10^7 n/s) on materials of differentcomposition (8 months); 4) optimization of the apparatus using the class A neutron generator (2 months); 5) test during trial neutron tomographies (2 months); 6) analysis of samples from public and private art collections (2 months).DESCRIPTION: This work package will be implemented by SEPA s.p.a., in collaborationwith the Dipartimento di Fisica Sperimentale of the University of Torino (DFS) and INFN.The work is subdivided in various phases, described below: 1) The first phase is relative to the design of the apparatus. This includes the part ofgamma ray detection which is usually obtained with more than one detector. In the mostadvanced systems a Germanium detector is used (HPGe) with a 65% efficiency andapproximately 2 keV resolution at 1333 KeV. Associated to this detector is a BGOscintillator for Compton scattering suppression. For rapid measurements anotherscintillator-photomultiplier system will be used. Also, the signal control electronics will bedesigned, the support structure and the detector shielding, which is necessary to reducebackground noise to a minimum and obtain high precision measurements. It will also benecessary to evaluate which acquisition software to use for spectrum analysis. In thisphase there will also be the design of a vacuum chamber to carry out high-sensitivitymeasurements on small samples. This will involve an adequate choice of materials(usually aluminium, due to its reduced interaction with neutrons), geometries and thewhole vacuum system. 2) The second phase, which will consist in the detector calibration, will be carried out in

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parallel to the shielding and support structure assembly in the INFN mechanical workshop((WP 6). The calibration will need to be carried out both to evaluate the efficiency and theenergy scale; for the first of the two, radioactive sources are necessary to generatephotons with characteristic energies up to 1500 keV (137Cs, 241Am, 60Co, 134Cs,152Eu and 133Ba) whilst to extend the scale up to approximately 11 MeV further peaksare necessary due to (n,g) reactions, e.g. those for Cl from KCl and nitrogen frommelanin, for which a neutron source is necessary, and will thus be carried out in the nextphase. The necessary radioactive sources for this calibration are already present at DFS,who will have a support role in this phase, with qualified personnel to carry out this type ofactivity. 3) The third phase will consist in tests of the installed structure by means of a class Bneutron source, which is less powerful than the source that will be installed in the finalversion, but is nevertheless fundamental to carry out the first measurements andcomplete the calibration up to high energies. In this way, all necessary tests on differentmaterials and it will be possible to evaluate the functionality of the spectrum acquisitionsoftware and if need be improve its performance. 4) The fourth phase, which will be carried out using the neutron source with a greater flux(WP 1 and 2) and the final structure, will consist of background measurements without asample, only with a neutron source. These will be performed in both configurations, i.e.both in a tomography simulation and in the installed analysis chamber. In this phase acalibration of standards will also be carried out to obtain a quantitative analysis asaccurate as possible and evaluate the detection limits of the system. 5) The fifth phase will consist in a detection test on large objects in a tomographymeasurement. Thus, it will be possible to evaluate the functionality of the whole apparatusand its integration with the tomography system. 6) The final phase will consist in tests on objects from public and private art collectionsand will allow to obtain first results of interest for the field of cultural heritage.ATTENDED RESULTS: The main result from this WP will be to obtain a structure to carryout the PGAA on large samples that would otherwise require sampling to be analysed.This will be of fundamental importance for the “La Venaria Reale” Centre, as they will allownot only neutron tomographies, but also composition analyses of large objects.Furthermore this structure will be capable of carrying out compositional analyses with highprecision, which is of fundamental importance in the field of cultural heritage for datingand origin analysis. To perform this WP, detector characterization will also be carried out; it will also bepossible to use it in other types of gamma measurements. One of the advantages of thistype of structure will be that it will not require the presence of a nuclear reactor, contraryto all other facilities perform this type of measurement. SEPA will obtain a number of advantages from this work, as it will develop instrumentationthat can be applied in other fields: PGAA can be used in all cases when particularelements need to be detected, especially light elements, with great precision, e.g. in theanalysis of new materials, or in the food industry to verify the absence of elements thatare dangerous for health. Furthermore, PGAA has numerous applications in chemistry,geology, archaeology, agriculture, environment studies, biology, medicine and industry. Deliverables.

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1) design and acquisition of the necessary material and instrumentation: month 12; 2) delivery of detector system: month 22; 3) report on detector performaces using radiation sources: month 22; 4) report on detector performaces using class B neutron source: month 30; 5) report on detector performaces using class A neutron source: month 32; 6) report on PGAA analysis using neutron CT apparatus: month 34; 7) report on first PGAA analysis on cultural heritage artifact: month 36.


AGENCY PARTICIPANT: FONDAZIONE CENTRO PER LA CONSERVAZIONE E ILRESTAURO DEI BENI CULTURALI "LA VENARIA REALE"STARTING MONTH PEOPLE ACTIVITIES: 24ENDING MONTH PEOPLE ACTIVITIES: 36PEOPLE/MONTHS ACTIVITIES FOR PARTICIPANT: 2


NUMBER: 5TITLE: X-Ray TomographyRESPONSIBLE: ALESSANDRO RESTARTING MONTH: 1ENDING MONTH: 36OBJECTIVES: The main objective of this work package is to obtain an apparatus forComputed axial Tomography (CT) using X-rays on objects of interest in the field ofcultural heritage. The intent is to obtain tomographies both on artefacts of considerablesize with a resolution of the order of medical CT scans (half a millimeter), and on smallerobjects with a higher resolution (below 0,5mm). Due to the numerous applications in the medical field, X-ray tomography is a well-established technique and operates with X-rays having and energy comprised between 30and 150 KeV. In the field of cultural heritage, however, new issues emerge. In somecases there is the need to internally characterize small objects with a higher resolution

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Participant to the Work Package: Prompt Gamma Activation Analysis

TOTAL PEOPLE/MONTHS OF ACTIVITY Prompt Gamma ActivationAnalysis: 95

Work Package: X-Ray Tomography

than in a medical CT (about 0.5 mm) or to analyze large objects (whose size exceeds thestandard 70 cm diameter) of irregular shape, which in some cases cannot be transferredfrom museums or from restoration centres. In the first case, to obtain high resolutions, an accurate design of the X-raygenerator/object/detector system is necessary, together with the use of non standardsources and detectors. In the second case, it is necessary to develop highly-flexible transportable systems toadapt to the different types of artefacts under investigation. This includes the use ofsources of various energies, to be defined based on preliminary studies on the constituentmaterials of the objects under study, the use of large detectors, and the development ofhigh-precision translational mechanical systems. One of the possible ways to attain CT scans on large objects with a high resolution is toadopt a detector having smaller dimensions than the object and to perform partial scansby translating the detector with a mechanical stage, so as to scan the entire field of visioncontaining the object. The partial scans need then to be merged together to obtain thecomplete scan. It is therefore very important to develop dedicated software applicationsboth to assemble the partial scans, starting from single radiographs performed on differentportions of the artefacts and from different views, both to reconstruct the completetomography and to enable the subsequent visualization of results. Complex imagemanagement tools are therefore necessary to highlight the aspects of interest for theexperts in the field of restoration. Concerning the large-scale objects, one of the objectives is to assemble a system insidethe DFS bunker that is essentially fixed, to be exploited in a complementary manner to theneutron tomography system (WP 1,6) in order to obtain complementary images to thelatter technique. Taking advantage of the INFN mechanical workshop, the apparatus willbe constructed in a suitably compact form as to be separated from the neutron CT systemand transported to the Venaria Centre for Conservation and Restoration or to museums inall cases when the artefact cannot be displaced to the DFS. The entire system willmaintain its characteristics of high flexibility necessary to study unique objects, but at thesame time will be designed so as to be operated by non-experts in nuclear physics. The final goal of this WP will be met through the following phases: 1) study, design and acquisition of the necessary material and instrumentation (10months); 2) characterization of the X ray source; construction and characterization of the detectors;construction of the mechanical structures (WP 6) (8 months); 3) integration of the mechanical structures (WP 6) with the source and detector,alignment, calibration and tests with the acquisition and management software developedby SEPA (6 months); 4) system optimization and verification of 3D reconstruction software developed in WP 7by means of a number of tomographies on reference objects with different compositionsand dimensions (8 months); 5) system validation with CT scans on cultural heritage artefacts from public and privatemuseum collections (4 months).DESCRIPTION: This WP will be managed by DFS in close collaboration with INFN andwith the research group at the University of Bologna that has been working on thesetopics for a number of years. The first phase consists in the study and design of the tomographic system to beassembled. Here, innovative solutions for the detector and the generation and use of X-rays will be evaluated. According to the project, the mechanical parts, housing, andstructures for system mobility will be defined together with the INFN mechanicalworkshop, together with all elements necessary for their functioning. Among thesestructures are the shielding and security devices necessary for radiation protection, to be

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defined and designed according to indications from qualified experts based on legalrequirements. At the end of this phase the detailed final project will be defined and X-raysources will be made available, as well as the commercial components for the detector(CCD, amorphous silicon panels, scintillation screens, focusing system, fibre opticsystems for imaging…). In the second phase, the sources and detectors will be characterized without thetranslations system. The possibility of using a beam collimator and shielding for the detector will be evaluated,to reduce background noise due to the interaction of X-rays with the electronic devices,producing noise and possible damage. In this phase, it is foreseen that optimalmeasurement parameters will be defined, such as the distance between the source, thedetector, and the object to be measured, the beam energy, the current and exposure time(which need to be adjusted according to the physical characteristics and dimensions ofthe object under analysis). Many tests will be required with materials of various compositions and thicknesses toprovide a first estimation of the measurement times necessary for various desireddimensions and resolutions. In this phase, novel detectors will be tested, exploiting the know-how emerging from high-energy experiments being carried out in this field by INFN Torino. Other detectors will alsobe considered for X-rays of higher energy than those commonly used for CT scans, inview of the possible acquisition of a linear particle accelerator for CT scans using above-MeV energies. The third phase will consist in the installation of the mechanical structure (WP 6) and itsintegration with the source and detector. The software for the movement of themechanical parts will be developed through the INFN – SEPA collaboration, and firstalignment and calibration tests for the whole instrument will be carried out. In this phase,the image acquisition software will be tested and future improvements will be evaluated.The possibility of completely integrating the image acquisition part with that of detectorpositioning in the case of large objects for which partial scanning is necessary will lead toa totally automated CT system, with a resulting reduction in acquisition time, use ofhuman resources, and operator error probability, as well as the opportunity to proceedwith the 3D image reconstruction in parallel with image acquisition. The fourth phase will be devoted to the first actual tomography tests on reference objects.These will be fundamental to evaluate the functionality of the whole system and will alsobe useful to test the image reconstruction software developed in WP 7. At the end of thisphase, the whole structure will be ready to perform measurements on real large scaleobjects of interest in the field of cultural heritage. In the final phase, system validation will be carried out on works of art from public andprivate museum collections.ATTENDED RESULTS: The main expected result is to obtain a flexible and innovativeinstrument for CT X-ray scans on large scale objects or high-resolution scans on smallobjects. The main apparatus will be coupled to the neutron tomography system developedin WP 6, but will also be constructed in such a manner as to be transportable. To reach this goal, source and detector characterization will be carried out, some of whichof new conception. The mechanical translation stages will be also adaptable to otherinstruments and will allow the use of additional sources and detectors to thosecontemplated in this proposal. At the conclusion of the project, the first tomographies will be obtained with thisapparatus, and thus there will be the availability for the Centro di Conservazione e

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Restauro “La Venaria Reale” of a structure for non-invasive analysis of statues and objectsof large dimensions. The compact structure of the apparatus will allow its displacement directly to the site ofanalysis, in the case of a particularly large or delicate object, which would not betransferable to DFS. All of this would entail consistent advantages for the Centro diConservazione e Restauro “La Venaria Reale”, which would acquire a powerful instrumentof considerable importance for the study and restoration of large scale artefacts. Forexample, in the case of wooden statues, it would be possible to obtain information on theirentire volume and detect in a non invasive manner the presence of defects (insect holes,decayed zones, etc.), growth rings for the study of ageing with dendrochronology, thestructure of the grain patterns, presence of fillers or nails, wood density, constructionstructure, etc.. It is to be observed that often the difficulties encountered in achieving a CT instrument inthe field of cultural heritage are quite similar to those present in other industrial fields(different sized and shaped objects with various densities, presence of inhomogeneities,metals and heavy materials, presence of various constitutive materials, significantthicknesses, scarce relevance of released dose). It is therefore clear that both sectors canbenefit from this type of service and from the applicative results obtained in this project.The growing interest in various industrial sectors for the technique CT brings thistechnology to attention in the field of non-destructive tests. This apparatus could therefore also be employed for other purposes, mainly industrial,e.g. the analysis of mechanical components with a resolution of about 100 µm or, in thecase of a linear accelerator, of large scale objects that are impossible to analyse withconventional CT instrumentation. This could be extremely important, to extend thediagnostic possibilities to a new class of materials (thicker and heavier), and thus toextremely interesting items in the field of cultural heritage (large bronze, stone and marbleartefacts) and simultaneously to open up the possibility of using CT scans in the analysisof heavy industrial components like aluminium or steel casts, or similar items. Deliverables: 1) design and acquisition of the necessary material and instrumentation: month 10; 2) delivery of all mechanical parts and detectors: month 18; 3) characterization of the X ray source: month 18; 4) report on final assembly of mechanical structure and detector performances: month 18; 5) delivery of the complete system and control software: month 24; 6) report on the whole system performances: month 32; 7) report on 3D reconstruction software performances: month 32; 8) report on first X-ray CT on cultural heritage artefacts: month 36.


AGENCY PARTICIPANT: FONDAZIONE CENTRO PER LA CONSERVAZIONE E ILRESTAURO DEI BENI CULTURALI "LA VENARIA REALE"STARTING MONTH PEOPLE ACTIVITIES: 1ENDING MONTH PEOPLE ACTIVITIES: 36

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Participant to the Work Package: X-Ray Tomography

PEOPLE/MONTHS ACTIVITIES FOR PARTICIPANT: 32



NUMBER: 6TITLE: Mechanical system for X-ray and neutron Computed TomographyRESPONSIBLE: PAOLO MEREUSTARTING MONTH: 1ENDING MONTH: 36OBJECTIVES: Main goal of the present WP is to provide to the neutron and X-ray source-detector systems a reliable, stable, and accurate numerically controlled mechanicalstructure to perform fast CT on artistic objects. Choice of the motor and control systemwill be crucial for achieving the desired performances. The flexibility of the structure in the relative positioning of the source, sample to beanalyzed and X-ray or neutron detector, will allow for each case a full optimization of theCT in terms of imaging resolution. The modularity of the structure will allow quick disassembly and reassembly to open thefeasibility of CT on artistic objects which could not be moved away from their location. Thedesign of the mechanics will be therefore organized to ease in the best possible wayreassembly and installation, and all the necessary manuals to make this operation will beprovided by the constructors. Special care will be taken in the radiation test of all mechanical linear encoders, whichshould operate and guarantee good performance in large neutron and X-ray radiationenvironment. This is an important aspect of the development of the mechanical structureand a relevant goal to be accomplished to operate satisfactorily the CT devices. Another important goal of this WP is the benchmarking of the software for the motorcontrol and interfaces for data acquisition, which will guarantee the correct machinebehaviour under operator control. Two software levels are foreseen and will be developedin the present WP. A low level software, developed at the motor control CPU level, willprovide have all the necessary executables and motor parameter definitions to bedownloaded in the motor control firmware system. A higher level software is the GUI(Graphic User Interface) which will allow user friendly interface of the operator with themotor control programs. This part of the software will be made in close collaboration ofINFN and University of Torino experts and co-proponent (SEPA) software developers.

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TOTAL PEOPLE/MONTHS OF ACTIVITY X-Ray Tomography: 140

Work Package: Mechanical system for X-ray and neutron ComputedTomography

DESCRIPTION: The design and construction of the mechanical part of the X-ray andneutron Computed Tomography system is under responsibility of the engineering staff ofthe Istituto Nazionale di Fisica Nucleare. The group of engineers and technicians involvedin this task has very good skills and experience in the planning and design of computercontrolled machine which have been developed and used in the INFN laboratories in thepast years for the construction of large area particle detectors. The accuracy required inHigh Energy Physics experiments, even at scales of the order of few meters, is betterthan 100 microns. On top of this, the accuracy in the planning and construction ofequipments used for particle detector assembly is crucial for the serial quality control of many detectors. For this reasons the INFN staff is well suited to design, develop, contruct,assemble and commission the CT mechanical structure with motion controls andmonitoring system. Moreover it should be stressed that the group has already beeninvolved in the construction of a part of a CT system used to apply CT analysis techniquesto a wooden statue of the 12th century actually located in the CCR “la Venaria Reale”. TheCT will be done in february in collaboration with INFN and University of Torino and INFNand Univeristy of Bologna. The CT mechanical system will be designed having in mind the following requirements: 1) precision and stability of x-y gantry. Fast motor control together with high mechanicalstability will be crucial in the image scanning and therefore in the CT system duty cyclepotential. The duty cycle is relevant to be considered from the very beginning as a keyparameter of the mechanical assembly. The structure infact should grant short CT timesin order to minimize the stationary period of art samples in our laboratories and to boostthe frequency of CT which can be performed. Positioning accuracy will be obtained withoptical linear encoders, which will allow single axis precision of the order of 0.01mm; 2) precision rotation platform with good encoder resolution. The object which will undergoCT will be placed on this device. The distance between the the x-y gantry holding the X-ray or neutron sensor and the platform will be tuned to maximize image resolution (aimingto perform better than 0.1mm); 3) y movement for vertical displacing of the X-ray source (necessary for CT to voluminousobjects). The design of all mechanical parts and interfaces will be done by INFN engineers.Construction of most parts will be done by INFN technicians in the INFN mechanicalworkshop in Torino. The full apparatus will be mounted and fully commissioned in theINFN workshop. The commissioning will include a campaign of measurements with alaser interferometer to certify and calibrate all axes movements and the full benchmarkingof all software controls. Later it will be transported in the bunker of the Istituto di Fisica ofTorino, where it will be reassembled and integrated with all the necessary parts(dosimeters, sources, radioprotections system, detectors). The structure will be disegned keeping in mind from the very beginning that it will be ableto operate both on X-ray and neutron beams. Moreover it will be modeled in order to beeasily transported (when needed) in other locations (for the X-ray analysis only). This willopen the possibility to carry on X-ray CT directly on the art samples in the location andplace where they are conserved, and therefore to export the application of this techniqueto a multiplicity of potentially interested museums and galleries.ATTENDED RESULTS: Mechanical complexity of CT systems is one of limiting factors ofthe diffusion of this imaging method in the cultural heritage field. We expect that the knowhow developed with INFN groups and invested in this WP, will enhance the diffusion andthe use of this non invasive analysis technique, both in cultural heritage and archeologyfields. The tight collaboration with researchers of CCR “La Venaria Reale” and with its

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School of Restoration will certainly have considerable profits from the use of thisadvanced analysis tool, both in terms of analysis of artistic samples prior restoration, andfor the formation of young restorers of the school who will take enormous advantage intheir professional preparation. The school will offer their student the possibility to work inclose collaboration with our groups and to use our facilities. The diffusion of the results,well amplified by the large visibility of CCR in our territory, will hopefully also stimulateinterest in X-ray and neutron CT analysis in other fields, in particular in industry, where itis known that both gamma and neutron imaging is often an invaluable tool for mechanical(expecially metallic) samples to be analyzed. This is particularly true for neutrons, whichhave known applications in the investigation of moisture and corrosion, the detection ofexplosives and adhesive connections and the inspection of defects in nuclear fuel or inthick metallic samples. The use of neutron CT tomography in industry is essentially limitedby the difficulty to have facilities like the one described in the current project, whichrequires not only expensive equipments but also a certified bunker with controlled accesspremises, and dedicated, experienced personnel trained not only to operate the structurebut also for the interpretation of the results. We also expect that the possibility to export X-ray CT in galleries and museums whichcannot transport artistic objects of their collections might generate spin-off in this field, afield which is certainly of great relevance in Italy for its very important tradition and theamount and importance of the national cultural heritage. Again it should be emphasizedthat the design of the mechanical system should be done, already at its earlier stage,having this possibility in mind. Deliverables: 1) full design of the mechanical structure: month 8 2) mechanical structure components and machined parts delivery: month 12 3) final mechanical structure assembly: month 18 4) report on mechanical structure commissioning: month 24 5) report on final commissioning with integrated devices (source and detectors): month 36


NUMBER: 7TITLE: X-Ray and neutron tomography and imagingRESPONSIBLE: FILIPPO DE CECCOSTARTING MONTH: 1

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Participant to the Work Package: Mechanical system for X-ray and neutronComputed Tomography

TOTAL PEOPLE/MONTHS OF ACTIVITY Mechanical system for X-ray andneutron Computed Tomography: 27

Work Package: X-Ray and neutron tomography and imaging

ENDING MONTH: 36OBJECTIVES: Accomplishment of the goals foreseen will be distributed in the three yearsprojects with the following breakdown: Year 1. . All the effort of the imaging team will be focused on developing a first working version ofthe reconstruction algorithms. Year 2. . Refinement of reconstruction algorithms. . Development of processing and visualization algorithms. Year 3. . Further development of processing and visualization tools. . Development of a GUI based software application integrating the algorithms. . Installation of the processing workstation hardware platform.DESCRIPTION: This WP deals with all activities related to software developments on CTimage processing algorithms, controls, handling and archiving. 1. Develop an image reconstruction algorithms customized to our X-rays and neutrontomography scanner. The aim of transmission tomography reconstruction algorithms is to reconstruct the spatialdistribution of X-rays or neutrons attenuation coefficients, i.e. the image, starting from theset of radiographic projections of the sample, acquired at different angles. As apreprocessing step, the acquired projections are transformed in sinograms, by coordinatetransformation and rebinning; here is when the cone-beam geometry of our scannersplays a role. Sinograms correspond to the Radon transform of the image, therefore,tomographic image reconstruction consists in fact, in inverting the Radon transform. Thefiltered back-projection (FBP) is a discretized and stabilized version of the inverse Radontransform, and it is one of the most widely employed analytic reconstruction algorithm. Itscomputational efficiency makes FBP suitable to treat large reconstruction volumes andhigh resolutions, such as those of our scanners. 2. To develop image reconstruction algorithms for the paintings X-rays and K-thresholdradiography scanner. In the paintings X-rays and K-threshold radiography, the detector acquires small 2Dimages while scanning the surface of the painting. All the partial images will be integratedin a single 2D image of the whole scanned area, and subtracted images will be calculatedfor K-threshold radiography. 3. Develop a set of image processing, registration, and analysis tools, for the detailed andquantitative examination of tomographic and radiographic images. Develop a 2D and 3D scientific visualization framework, allowing optimal inspection andanalysis of different types of cultural heritage artworks, with our imaging modalities. In order to allow a detailed examination of tomographic images, several processing andvisualization algorit

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Regione Piemonte - Bando Converging technologies 2007 ...personalpages.to.infn.it/~staiano/web-neuART/proposta_finale.pdf · study of textile, argillaceous and ligneous artworks,