Rare ISotope INvestigation at GSI

+ Notre Dame, LBNL, Youngstown (USA), ANU (Australia), ……Notre Dame, LBNL, Youngstown (USA), ANU (Australia), ……

Decay Studies of Exotic Nuclei with RISING & the GSI Fragment Separator

   

 Part of the ‘Stopped Beam’ RISING experimental campaign at GSI. 

PARTICIPANTS CENBG Bordeaux, France: B. BlankGSI-Darmstadt, Germany: J.Gerl, H.J.Wollersheim, F.Becker, H.Grawe, M.Gorska, P.Bednarczyk, N.Saitoh, T.SaitohIKP Koeln, Germany: J.JolieJ.Jolie, P. Reiter, N. Warr, A. Richard, A. Scherillo, N. Warr TU Munchen, Germany: R. Krücken, T. FaestermannUniversity of Camerino, Italy: D. Balabanski, K.Gladnishki, IFJ PAN Krakow, Poland: A. Maj, J. Grebosz, M. Kmiecik, K. Mazurek Warsaw University, Poland: M. PfűtznerUniversidad Autonoma de Madrid, Spain: A.JungclausA.JungclausUniversidad de Santiago de Compostela, Spain: D. Cortina Gil, J.BenlliureJ.Benlliure, T. Kurtukian Nieto, E. CaserejosIFIC Valencia, Spain: B. RubioINFN-Legnaro, Italy: A. Gadea, G. deAngelis, J.J. Valiente Dobon, N. Marginean, D. Napoli, INFN-Padova, Italy: E. Farnea, D. Bazzacco, S. Lunardi, R. MargineanUniversity and INFN-Milano, Italy: A. Bracco, G. Benzoni, F. Camera, B. Million, O. Wieland, S. LeoniUniversity of Surrey, UK: Zs.PodolyàkZs.Podolyàk, P.H.ReganP.H.Regan,, P.M. Walker, W.GelletlyW.Gelletly, W.N.Catford, Z. Liu, S. WilliamsUniversity of York, UK: M.A. Bentley, R. WadsworthUniversity of Brighton, UK: A.M.BruceA.M.BruceUniversity of Manchester, UK: D.M. Cullen, S.J. FreemanUniversity of Liverpool, UK: R.D. PageUniversity of Edinburgh, UK: P. Woods, T. DavinsonCLRC Daresbury, UK: J. Simpson, D. WarnerUppsala University, Sweden: H. MachLund University, Sweden: D.RudolphD.RudolphLawrence Berkeley National Lab, USA: R.M. ClarkUniversity of Notre Dame, USA: M. Wiescher, A. AprahamianYoungstown State University, Ohio, USA: J.J. CarrollDebrecen, Hungary: A. Algora

Overall Physics Aims and Technical Background

• Use of FRS and RISING gamma-ray spectrometer to study internal structure of extremely exotic nuclei.

• Relativistic projectile fragmentation to populate – Heavy, neutron-rich nuclei (cold fragmentation). – N~Z nuclei approaching the proton drip-line.

• Active, position sensitive, pixellated stopper to correlate implanted ions (mother) with -decay.

• Measure rays (internal structure) from decays of– ns-ms isomeric states in implanted ion, and / or– excited states in -daughter nucleus.

Fragmentation at relativistic energies

abrasion ablation

fragmentation

Rare Isotope Production at GSI

relativistic energies: 0.2 – 1 GeV/amu

- fragmentation reactions

- fission after peripheral collisions

1. N~1261. N~126

2. 2. 190190W - W - 170170DyDy

3. 3. 128,130128,130CdCd4. 4. 7171KrKr5. 5. 8282Nb, Nb, 8686TcTc

7. Zr, Mo, A~1107. Zr, Mo, A~1106. 6. 5454NiNi

N=Z line

eg. R. Grzywacz et al. Phys. Rev. C55 (1997) p1126 LISE M. Pfützner et al. Phys. Lett. B444 (1998) p32 FRS Zs. Podolyàk et al. Phys. Lett. B491 (2000) p225 FRS M. Pfützner et al. Phys Rev. C65 (2002) 064604 FRS M. Caamano et al., Eur. Phys. J. A23 (2005) p201 FRS

primary beamPb @ 1GeV/u

Production target

Central focus, S2Final focus, S4

E(Z2)

cu

eB

Q

A

FTO

catcher

degrader

degrader

dipole, B

scintscint

MW=x,y

scint(veto)

In-Flight Technique Using Projectile Fragmentation

Use Fragment Separator to ID individual nuclei. Transport some in isomeric states (TOF~ x00ns).Stop and correlate decays with nuclei id.

C. Chandler et al. Phys. Rev. C61 (2000) 044309

67Ge

69Se

76Rb

92Mo fragmentation on natNi target

Heaviest odd-odd,N=Z gammas, isobaric analog states ? N=Z=43; 86Tc, C. Chandler et al. Phys. Rev. C61 (2000) 044309

~500 86Tc in ~ 1 week

208Pb beam at 1 GeV/u showed production of heavy, neutron-rich (A>170-200) high-spin (>35/2 h) isomers.

Pfützner et al. Phys Rev. C65 (2002) 064604

High spins (>35/2) populated

Walker, Dracoulis et al., Nuc. Phys. A568 (1994) 397

Higher spins for greater A.

M. Pfützner et al., Phys. Rev. C65 (2002) 064604; K. Gladnishki et al., Phys. Rev. C69 (2004) 024617

14.3 ns

M. Caamano et al., Eur. Phy. J A23 (2005) p201

Stripping the ions of electrons lengthens the apparent isomeric decay half-life by ‘switching off’ conversion electron decay branch

Fragmentation of 1 GeV/u 208Pb, M. Caamano et al., Eur. Phy. J A23 (2005) p201

fully-stripped H-like

184Lu, H-like fully-stripped

188Ta

Prompt ‘flash’ can be a limiting problem for fragmentation isomer spectroscopy.

Can reduce the effective Ge efficiency factors of 3-4 for close geometry….

but 105 (15 x 7) detectors in RISING will improve this.

RISING set-up with stopped beams

RISING GeCluster Array.

MUSIC MUSIC

Sci

41

MW

41 MW

42

deg

rad

er

beambeam

5 at 510, 5 at 900 and 5 at 1290 all at 209.8mm Photopeak efficiency 17.2% at 1.3MeV

8 BaF2 detectors (185-220mm) 

5 at 510, 5 at 900 and 5 at 1290 all at 209.8mm Photopeak efficiency 17.2% at 1.3MeV

8 BaF2 detectors (185-220mm) 

Stopped Beam RISING Campaign Accepted Proposals

Nuclei interest

Spokespersons

ß-decay lifetimes, ß-decay spectroscopy studies and collective evolution "south" of 208Pb S312

N~126 south of 208Pb

J. Benlliure, P.H.Regan

Nuclear dynamical symmetries and shape evolution in K-isomeric nuclei from 190W to the 170Dy val. max. S313

190W- 170Dy

P.H. Regan, J.Benlliure

Search for the 8+ (πg9/2)-2 isomer in N=82 130Cd via 6 proton knockout from 136Xe fragmentation S305

130Cd A. Jungclaus

Shape co-existence and X(5) behaviour in neutron-rich A~110 nuclei S300

106Zr A.M. Bruce

Along the N=126 closed shell: Nuclei below 208Pb S299

N=126Z<82

Z. Podolyak

Isospin symmetry of transitions probed by weak and strong interactions: the ß-decay of 54Ni, 50Fe, and 46Cr S316

54Ni, 50Fe, 46Cr

Y.Fujita, W.Gelletly, B.Rubio

+ ‘old’

N=Z=41-43(Regan, Blank, Rudolph Wiescher)

+

54Ni/54Fe mirrorSymmetry (Rudolph et al.,)

197Au+9Be

5p

4p

Cold fragmentation (protons out) to produce neutron-Cold fragmentation (protons out) to produce neutron-rich nuclei is well modelled by theoretical estimates. rich nuclei is well modelled by theoretical estimates.

B. Fornal et al., Phys. Rev. Lett. 87 (2001) 212501

208Pb -> 206Hg (2p knockout)I= 10+ = 0.25mbI= 8+ = 0.20mb I= 7- = 0.20 mbI= 5- = 0.15mb

N=126, Z=80 206Hg(idealised 2hole system)

Seniority (h11/2)-210+ probes knock-out theory (see Jeff Tostevin Fri.)

more ways of knocking out a pair of high-j orbitals than low-j ones. Isomeric RatioIsomeric Ratio gives test of reaction mechanism / spin population.

Proposal A:2 (S313)

Nuclear Dynamical Symmetries and Shape Evolution in

K-isomeric Nuclei from 190W to the 170Dy Valence Maximum.

 P.H. Regan, J. Benllliure et al.,

Department of Physics, University of Surrey, Guildford, GU2 7XH, UKUniversity of Santiago de Compostela, Spain

IKP, University of Cologne, 50937 Cologne, GermanyPlanckstrasse 1, GSI, Germany

Warsaw University, PolandUppsala University, Sweden

CLRC Daresbury Laboratory, Cheshire, UK University of Camerino, ItalyUniversity of Manchester, UK

Youngstown State University, Ohio, USA IJF, PAN Krakow, Poland

STOPPED BEAM CAMPAIGN - A

Podolyak et al., Phys. Lett. 491B (2000) 225;Caamano et al., EPJ A23 (2005) 201

Discontinuity (change of structure)observed for 190W following GSI isomer (K=10-) spectroscopy.

0

50

100

150

200

250

300

350

400

450

Yb (70) Hf (72) W (74) Os (76) Pt (78)

108

110

112

114

116

118

120

122

E(2E(2++) is signature of deformation. Possible shape change ) is signature of deformation. Possible shape change identified from identified from 190190W data point (N=116).W data point (N=116).

Proposal to identify Proposal to identify first 2first 2++ state in state in 192192W (N=118)W (N=118)188,190188,190Hf (N=116,118)Hf (N=116,118)186,188186,188Yb (N=116,118)Yb (N=116,118)

Decays from IDecays from I=10=10- -

isomers and/orisomers and/or -- decay of decay of 192192TaTa188,190188,190Lu andLu and186,188186,188Tm Tm

tt1/21/2 ~1-5 secs ~1-5 secs

Constrained HF calculations (P.D.Stevenson)suggest prolate-oblate shape change/competition at N=116 isotones, 188Hf, 190W, etc.

Physics interpretation consistentwith O(6) ‘critical point’ in extended ‘Casten triangle’ at phase transitionbetween prolate and oblate axially symmetric shapes.See J. Jolie and A. Linnemann, Phys. Rev. C68 (2003) 031301(R)

170Dy, double mid-shell, nature’s purest K-isomer ? P.H. Regan et al. Phys. Rev. C65 (2002) 037302

Reduced hindrance correlated with N.N…max. at 170Dy...

K=6+ isomer

K=0+ band

Primary 198Pt beam @ 1GeV/u, intensity of 109 particles per spill, 10 second spill cycle. 2.5 g/cm2 thick Be target, 5.1g/cm2 Al. degrader at S2, plus a 108mg/cm2 Niobium stripper. Cross-section estimates from the COFRA.Estimated values for transmission per eight hour

shift are: Setting 1: Centred on 191W

190W 1x107 191W 0.4x107 192W 0.4 x107

Setting 2: Centred on 187Hf 187Hf 3.7x105 188Hf 9x104 189Hf 1x104

Setting 3: Centred on 185Yb 184Yb 2x104 185Yb 6x103 186Yb 240

 20% -ray efficiency for 662 keV, (~50%) prompt-flash, isom. ratio

(~5%), Yield estimates for observed photopeak rays per 8 hour shift of  190W 250,000 ; 192W 100,000 ; 188Hf 2,250 ; 184Yb 500 ; 186Yb 6  Setting 4: Centred on 170Dy

170Dy 1.4x105 170Tb 4,500 168Tb 4.9x104

 Assuming -ray (0.2) and -detection (0.5) efficiency for decays of 170Tb

gives 450 photopeak rays from the decay of the first 2+ state in 170Dy per

shift.  Setting 1: 3 shifts (1 day) ; Setting 2: 3 shifts (1 days)Setting 3: 6 shifts (2 days) ; Setting 4: 6 shifts (2 days)2 days (6 shifts) primary beam tuning and particle id. calibrations, 191W

setting:Total beam request of 24 shifts (8 days). 

Proposal A:3 (S305)

 Search for the 8+ (g9/2)

-2 isomer in N=82 130Cd populated via the 6 proton knockout channel in the

fragmentation of 136Xe 

A. Jungclaus et al., 

Universidad Autónoma de Madrid, Spain Institute of Nuclear Research, Debrecen, Hungary

Universidad de Santiago de Compostela, SpainGSI Darmstadt, Germany

Uppsala University, SwedenUniversity of Surrey, UK

Universität zu Köln, Germany University Warsow, Poland

IFIC Valencia, Spain Lund University, Sweden

STOPPED BEAM CAMPAIGN - A

Search for the 8+ (g9/2)-2 isomer in N=82 130Cd populated

via the 6 proton knockout channel in the fragmentation of 136Xe

Why study 130Cd ?

astrophysical reasons:

130Cd is the most important waiting-point nucleus before the r-process breakout of the N=82 shell

relation between N=82 shell closure and the A~130 peak of the solar r-process abundance distribution

r-process path

N=82

Z=50

130Cd

132Sn

nuclear structure reasons:

unexpected behaviour of the 2+ excitation energies of even Cd isotopes towards the N=82 shell closure (change of curva- ture starts already at 124Cd)

there is a series of other nuclear structure puzzles in the 132Sn region

Is this behaviour really a “signature of a weakening of the N=82shell structure already one proton-pair below 132Sn” as suggestedby the authors of the experimental study ?

50 54 58 62 66 70 74 78 82

400

800

1200

1600 Pd Cd Sn Te

E(2

+ ) [k

eV]

neutron number N

-decay @ ISOLDEKautsch et al., EPJ A9 (2000) 201

Sn

TeCd

Pd

NiZn

Ge

Gd

54 56

524846444240383634323028

Sr

Mo

Ru

Pd

Cd

100Sn Te

Xe

Ba

Ce

Nd

Sm

58 60 62

68 70

72

7476 78

8082

Z

50

50

N=Z

132Sn

98Cd 102Sn 134Sn 130Sn134Te130Cd

(g9/2)-2 (d5/2 g7/2)2 (g9/2)-2 (f7/2)2 (g7/2)2 (h11/2)-2

0+

8+

0+

6+

0+

6+

165 ns

1.6 s

80 ns

480 ns

1.0 s

0+ 0+0+

6+

4+

2+

2+

2+

4+

4+

4+6+

2+

4+6+

2+

8+10+

?

N

8+ isomer with (g9/2)-2 con-figuration expected in 130Cdin analogy to the one in 98Cd

Study of 8+ isomer decay in 130Cd (and 128Cd)

already searched for withoutsuccess at LOHENGRIN andFRS (Mineva, Hellström et al.)

Advantage compared to -decay:• possible observation of whole sequence up to the 8+ state• lifetime of the isomer itself contains valuable information

Production of 130Cd @ FRS

238U fissioncold fragmentation

of 136Xe

implantation rate at the focal plane:

I [sec-1] = [cm2] · d[g/cm2] · A-1[mol/g] · [sec-1] · Ttot · NA[mol-1]

cross section

target thickness d

primary beam current

total transmission

0.1 bcalc. !

0.154 nbmeasured !

1 g/cm2 2.5 g/cm2

109/spill (15s) 5·109/spill (5s)

3.5% 95%

1.4 (2000)0.9 (1300)implanted 130Cd/min(d)

for Be target

Mineva et al.:=2·107 sec-1

in total 700implanted 130Cd measured

easier beameasier exp.

University of SurreySCHOOL OF ELECTRONICS AND PHYSICAL SCIENCES

Department of PhysicsPost-Doctoral Research Fellow in Experimental Nuclear Physics

JOB(Ref: 5077)Salary: Up to £24,820 per annum

(subject to experience and qualifications) Applications are invited for the position of Research Fellow in the Nuclear Physics Group to undertake research to study the structure of atomic nuclei with highly exotic proton to neutron ratios following their production via projectile fragmentation reactions at the GSI laboratory in Germany as part of the RISING collaboration. You will be expected to help perform research with initiative and a reasonable degree of independence with particular focus on the physics arising from isomer and beta-delayed spectroscopic studies of heavy, neutron-rich nuclei as part of the Stopped Beam RISING collaboration. Experience in structural studies of exotic nuclei with particular emphasis on the production of nuclei with projectile fragmentation reactions and/or gamma-ray spectroscopy following decays from beta-decays/isomeric states would be an advantage with a PhD in experimental nuclear physics or expect to receive such an award in the near future.You will need to spend a significant period of the initial part of the project at the GSI facility in Darmstadt, Germany, providing technical expertise to the successful running of the experiments of the RISING Stopped Beam Campaign. Later in the grant period, you will lead the development of a new pixellated silicon detection system for the measurement of beta particles following the implantation of exotic projectile fragments at the focal plane of the GSI Fragment Separator. This post is initially for 2 years, with the prospect of renewal for a further two years, subject to performance. The post is available from October 2005 so we are looking for you to start as soon as possible. For further information about the Department of Physics visit http://www.ph.surrey.ac.uk/ Informal enquiries can be made to Dr Paddy Regan by e-mail: p.regan@surrey.ac.uk For full job and application details visit http://www.surrey.ac.uk/ and click on ‘Working at UniS’ or contact Becky McTigue on Tel: +44 (0) 1483 686126 or email b.mctigue@surrey.ac.uk Please quote Post Ref No. 5077, supply your postal address and where you saw this advertisement.  Closing date for applications is: Thursday 15 September 2005 

The University is committed to an Equal Opportunities Policy

GREAT

GREAT

JOB !!

!!

JOB !!

!!GREAT

GREATJOB !!!!

JOB !!!!

Isomer Spectroscopy of 91Zr

B.A. Brown et al., Phys. Rev. C13 (1976) 1900Expt. s.p.e. for N=51 and Z=41well known.

Simple 88Sr core allows max. spins of

(g9/2)28+ x d5/2

= 21/2+ (Ex= 3.17 MeV) (g9/2)2

8+ x g7/2 = 23/2+ (Ex ~ 5 MeV) (g9/2)2

8+ x h11/2 = 27/2- (Ex ~ 5.5 MeV)

Allowing 4 protons in (g9/2) gives extra4 ħ, ie. (g9/2)2

12+ x d5/2 = 29/2+

(g9/2)212+ x g7/2 = 31/2+

(g9/2)212+ x h11/2 = 35/2-

Higher spins require N=50 core breaking.

I=21/2+,=6s

Experimental Details

• 13C beam @ 50 MeV, 200g/cm2 82Se target

• s detected with 10 Clovers + 2 LEPS

• 91Zr (+4n) predicted to have ~500 mb

• Faraday cup acted as 'stopper' for isomer(s).

5 cm

92Zr data agrees with data from fusion-fission data from Fotiades et al., Phys. Rev. C65 (2002) 044303 and Pantelica et al., Phys. Rev. C72 (2005) 024304

178Hf (Z=72) + 27Al (Z=13) Z=85, N=110 fusion-fission to 91ZrG.A. Jones, private communication. (from GS expt. at ATLAS).

305

1545901

2170 keV delayed gate

Projected earlies on double delayed {2170}.{859} keV gate below 21/2

+ isomer in 91Zr…candidates for transitions above!

90 keV859 keV

290 keV

transitions identifiedbelow 21/2+ isomer in 91Zr, B.A.Brown et al., PR C13 (1976) 1900.

Simple 88Sr core allows max. spins of

(g9/2)28+ x d5/2

= 21/2+ (Ex= 3.17 MeV)

(g9/2)28+ x g7/2 = 23/2+ (Ex ~ 5 MeV)

(g9/2)28+ x h11/2 = 27/2- (Ex ~ 5.5 MeV)

Allowing 4 protons in (g9/2) gives extra

4 ħ, ie. (g9/2)212+ x d5/2 = 29/2+

(g9/2)212+ x g7/2 = 31/2+

(g9/2)212+ x h11/2 = 35/2-

Higher spins require N=50 core breaking.

25/2+ ?

27/2+ ?27/2- ?

23/2+ ?23/2+ ?

88Se core sen. 3 val.max.

29/2 35/2 ?

Seniority 5 Val. Max ?

> 35/2 N=50 core breaking

P.H. Regan1, N.J. Thompson1,2, A.B. Garnsworthy1,2, H.C. Ai2, L. Amon2,3, R.B. Cakirli2,3, R.F. Casten2, C. Fitzpatrick1,2, S.J. Freeman4,

G. Gurdal5, A. Heinz2, G.A. Jones1, E.A. McCutchan2, J. Qian2, V. Werner2, S.J. Williams1, R. Winkler2

1Dept. of Physics, University of Surrey, Guildford, GU2 7XH, UK2WNSL Yale University, 272 Whitney Avenue, New Haven CT 06520 , USA

3Dept. of Physics, Istanbul University, Istanbul, Turkey4School of Physics and Astronomy, The University of Manchester,

Manchester, M13 9PL, UK 5Clark University Worcester, Mass. 01610, USA