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. Blank GSI-Darmstadt, Germany: J.Gerl, H.J.Wollersheim, F.Becker, H.Grawe, M.Gorska, P.Bednarczyk, N.Saitoh, T.Saitoh J.Jolie IKP Koeln, Germany: J.Jolie, P. Reiter, N. Warr, A. Richard, A. Scherillo, N. Warr TU Munchen, Germany: R. Krücken, T. Faestermann University of Camerino, Italy: D. Balabanski, K.Gladnishki, IFJ PAN Krakow, Poland: A. Maj, J. Grebosz, M. Kmiecik, K. Mazurek Warsaw University, Poland: M. Pfűtzner A.Jungclaus Universidad Autonoma de Madrid, Spain: A.Jungclaus J.Benlliure Universidad de Santiago de Compostela, Spain: D. Cortina Gil, J.Benlliure, T. Kurtukian Nieto, E. Caserejos IFIC Valencia, Spain: B. Rubio INFN-Legnaro, Italy: A. Gadea, G. deAngelis, J.J. Valiente Dobon, N. Marginean, D. Napoli, INFN-Padova, Italy: E. Farnea, D. Bazzacco, S. Lunardi, R. Marginean University and INFN-Milano, Italy: A. Bracco, G. Benzoni, F. Camera, B. Million, O. Wieland, S. Leoni Zs.PodolyàkP.H.Regan,W.Gelletly University of Surrey, UK: Zs.Podolyàk, P.H.Regan, P.M. Walker, W.Gelletly, W.N.Catford, Z. Liu, S. Williams University of York, UK: M.A. Bentley, R. Wadsworth A.M.Bruce University of Brighton, UK: A.M.Bruce University of Manchester, UK: D.M. Cullen, S.J. Freeman University of Liverpool, UK: R.D. Page University of Edinburgh, UK: P. Woods, T. Davinson CLRC Daresbury, UK: J. Simpson, D. Warner Uppsala University, Sweden: H. Mach D.Rudolph Lund University, Sweden: D.Rudolph Lawrence Berkeley National Lab, USA: R.M. Clark University of Notre Dame, USA: M. Wiescher, A. Aprahamian Youngstown State University, Ohio, USA: J.J. Carroll Debrecen, 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~ W Dy ,130 Cd Kr Nb, 86 Tc 7. Zr, Mo, A~ Ni 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)  FRS M. Caamano et al., Eur. Phys. J. A23 (2005) p201  FRS primary beam 1GeV/u Production target Central focus, S2 Final focus, S4  E(Z 2 ) catcher degrader dipole, B  scint 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) Ge 69 Se 76 Rb 92 Mo fragmentation on nat Ni target

Heaviest odd-odd,N=Z gammas, isobaric analog states ? N=Z=43; 86 Tc, C. Chandler et al. Phys. Rev. C61 (2000) ~ Tc in ~ 1 week

208 Pb beam at 1 GeV/u showed production of heavy, neutron-rich (A> ) high-spin (>35/2 h) isomers. Pfützner et al. Phys Rev. C65 (2002) 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) ; K. Gladnishki et al., Phys. Rev. C69 (2004)

370 ions!. Useful information can be obtained with very low production rates, e.g., Fragmentation of 1 GeV/u 238 U to populate  g 9/2 2 isomer in 212 Pb. M. Pfützner et al., Phys. Lett. B444 (1998) 32

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 208 Pb, M. Caamano et al., Eur. Phy. J A23 (2005) p201 fully-stripped H-like 184 Lu, H-like fully-stripped 188 Ta

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 Ge Cluster Array. MUSIC Sci41 MW41 MW42 degrader beam

5 at 51 0, 5 at 90 0 and 5 at all at 209.8mm Photopeak efficiency 17.2% at 1.3MeV 8 BaF 2 detectors ( mm)

5 at 51 0, 5 at 90 0 and 5 at all at 209.8mm Photopeak efficiency 17.2% at 1.3MeV 8 BaF 2 detectors ( mm)

Stopped Beam RISING Campaign Accepted Proposals Nuclei interest Spokespersons ß-decay lifetimes, ß-decay spectroscopy studies and collective evolution "south" of 208 Pb S312 N~126 south of 208 Pb J. Benlliure, P.H.Regan Nuclear dynamical symmetries and shape evolution in K-isomeric nuclei from 190 W to the 170 Dy val. max. S W- 170 Dy P.H. Regan, J.Benlliure Search for the 8 + (πg 9/2 ) -2 isomer in N= Cd via 6 proton knockout from 136 Xe fragmentation S CdA. Jungclaus Shape co-existence and X(5) behaviour in neutron-rich A~110 nuclei S ZrA.M. Bruce Along the N=126 closed shell: Nuclei below 208 Pb S299 N=126 Z<82 Z. Podolyak Isospin symmetry of transitions probed by weak and strong interactions: the ß- decay of 54 Ni, 50 Fe, and 46 Cr S Ni, 50 Fe, 46 Cr Y.Fujita, W.Gelletly, B.Rubio + ‘old’ N=Z=41-43 (Regan, Blank, Rudolph Wiescher) + 54 Ni/ 54 Fe mirror Symmetry (Rudolph et al.,)

197 Au+ 9 Be 5p 4p Cold fragmentation (protons out) to produce neutron-rich nuclei is well modelled by theoretical estimates.

B. Fornal et al., Phys. Rev. Lett. 87 (2001) Pb -> 206 Hg (2p knockout) I  = 10 + = 0.25mb I  = 8 + = 0.20mb I  = 7 - = 0.20 mb I  = 5 - = 0.15mb N=126, Z=80  206 Hg (idealised 2hole system) Seniority (  h 11/2 ) probes knock-out theory (see Jeff Tostevin Fri.) more ways of knocking out a pair of high-j orbitals than low-j ones. Isomeric Ratio Isomeric Ratio gives test of reaction mechanism / spin population.

Proposal A:2 (S313) Nuclear Dynamical Symmetries and Shape Evolution in K-isomeric Nuclei from 190 W to the 170 Dy Valence Maximum. P.H. Regan, J. Benllliure et al., Department of Physics, University of Surrey, Guildford, GU2 7XH, UK University of Santiago de Compostela, Spain IKP, University of Cologne, Cologne, Germany Planckstrasse 1, GSI, Germany Warsaw University, Poland Uppsala University, Sweden CLRC Daresbury Laboratory, Cheshire, UK University of Camerino, Italy University 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 190 W following GSI isomer (K  =10 - ) spectroscopy.

E(2 + ) is signature of deformation. Possible shape change identified from 190 W data point (N=116). Proposal to identify first 2 + state in 192 W (N=118) 188,190 Hf (N=116,118) 186,188 Yb (N=116,118) Decays from I  =10 - isomers and/or  - decay of  - decay of 192 Ta 188,190 Lu and 186,188 Tm t 1/2 ~1-5 secs

Constrained HF calculations (P.D.Stevenson) suggest prolate-oblate shape change/competition at N=116 isotones, 188 Hf, 190 W, etc. Physics interpretation consistent with O(6) ‘critical point’ in extended ‘Casten triangle’ at phase transition between prolate and oblate axially symmetric shapes. See J. Jolie and A. Linnemann, Phys. Rev. C68 (2003) (R)

170 Dy, double mid-shell, nature’s purest K-isomer ? P.H. Regan et al. Phys. Rev. C65 (2002) Reduced hindrance correlated with N .N …max. at 170 Dy... K  =6 + isomer K  =0 + band

Primary 198 Pt 1GeV/u, intensity of 10 9 particles per spill, 10 second spill cycle. 2.5 g/cm 2 thick Be target, 5.1g/cm 2 Al. degrader at S2, plus a 108mg/cm 2 Niobium stripper. Cross-section estimates from the COFRA.Estimated values for transmission per eight hour shift are: Setting 1: Centred on 191 W 190 W 1x W 0.4x W 0.4 x10 7 Setting 2: Centred on 187 Hf 187 Hf 3.7x Hf 9x Hf 1x10 4 Setting 3: Centred on 185 Yb 184 Yb 2x Yb 6x Yb %  -ray efficiency for 662 keV, (~50%) prompt-flash, isom. ratio (~5%), Yield estimates for observed photopeak  rays per 8 hour shift of 190 W 250,000 ; 192 W 100,000 ; 188 Hf 2,250 ; 184 Yb 500 ; 186 Yb 6 Setting 4: Centred on 170 Dy 170 Dy 1.4x Tb 4, Tb 4.9x10 4 Assuming  -ray (0.2) and  -detection (0.5) efficiency for decays of 170 Tb gives 450 photopeak  rays from the decay of the first 2 + state in 170 Dy 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, 191 W setting: Total beam request of 24 shifts (8 days).

Proposal A:3 (S305) Search for the 8 + (  g 9/2 ) -2 isomer in N= Cd populated via the 6 proton knockout channel in the fragmentation of 136 Xe A. Jungclaus et al., Universidad Autónoma de Madrid, Spain Institute of Nuclear Research, Debrecen, Hungary Universidad de Santiago de Compostela, Spain GSI Darmstadt, Germany Uppsala University, Sweden University of Surrey, UK Universität zu Köln, Germany University Warsow, Poland IFIC Valencia, Spain Lund University, Sweden STOPPED BEAM CAMPAIGN - A

Search for the 8 + (  g 9/2 ) -2 isomer in N= Cd populated via the 6 proton knockout channel in the fragmentation of 136 Xe Why study 130 Cd ? astrophysical reasons: 130 Cd 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= Cd 132 Sn

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 124 Cd) there is a series of other nuclear structure puzzles in the 132 Sn region Is this behaviour really a “signature of a weakening of the N=82 shell structure already one proton-pair below 132 Sn” as suggested by the authors of the experimental study ?  ISOLDE Kautsch et al., EPJ A9 (2000) 201 Sn Te Cd Pd

8 + isomer with (  g 9/2 ) -2 con- figuration expected in 130 Cd in analogy to the one in 98 Cd Study of 8 + isomer decay in 130 Cd (and 128 Cd) already searched for without success at LOHENGRIN and FRS (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 130 FRS 238 U fission cold fragmentation of 136 Xe implantation rate at the focal plane: I [sec -1 ] =  [cm 2 ] · d[g/cm 2 ] · A -1 [mol/g] ·  [sec -1 ] · T tot · N A [mol -1 ] cross section  target thickness d primary beam current  total transmission  0.1  b calc. !  nb measured ! 1 g/cm g/cm /spill (15s)5·10 9 /spill (5s)  3.5%  95% 1.4 (2000)0.9 (1300) implanted 130 Cd/min(d) for Be target Mineva et al.:  =2·10 7 sec -1 in total 700 implanted 130 Cd measured  easier beam easier exp.

University of Surrey SCHOOL OF ELECTRONICS AND PHYSICAL SCIENCES Department of Physics Post-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 Informal enquiries can be made to Dr Paddy Regan by For full job and application details visit and click on ‘ Working at UniS ’ or contact Becky McTigue on Tel: +44 (0) or 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 JOB !!!! GREAT

Isomer Spectroscopy of 91 Zr

B.A. Brown et al., Phys. Rev. C13 (1976) 1900 Expt. s.p.e. for N=51 and Z=41well known. Simple 88 Sr core allows max. spins of (  g 9/2 ) 2 8+ x d 5/2 = 21/2 + (E x = 3.17 MeV) (  g 9/2 ) 2 8+ x g 7/2 = 23/2 + (E x ~ 5 MeV) (  g 9/2 ) 2 8+ x h 11/2 = 27/2 - (E x ~ 5.5 MeV) Allowing 4 protons in (  g 9/2 ) gives extra 4 , ie. (  g 9/2 ) x d 5/2 = 29/2 + (  g 9/2 ) x g 7/2 = 31/2 + (  g 9/2 ) x h 11/2 = 35/2 - Higher spins require N=50 core breaking. I  =21/2 +,  =6  s

Experimental Details 13 C 50 MeV, 200  g/cm 2 82 Se target  s detected with 10 Clovers + 2 LEPS 91 Zr (+4n) predicted to have  ~500 mb Faraday cup acted as 'stopper' for isomer(s).

5 cm

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

178 Hf (Z=72) + 27 Al (Z=13)  Z=85, N=110 fusion-fission to 91 Zr G.A. Jones, private communication. (from GS expt. at ATLAS) keV delayed gate Projected earlies on double delayed {2170}.{859} keV gate below 21 / 2 + isomer in 91 Zr…candidates for transitions above! 90 keV 859 keV 290 keV transitions identified below 21/2 + isomer in 91 Zr, B.A.Brown et al., PR C13 (1976) 1900.

Simple 88 Sr core allows max. spins of (  g 9/2 ) 2 8+ x d 5/2 = 21/2 + (E x = 3.17 MeV) (  g 9/2 ) 2 8+ x g 7/2 = 23/2 + (E x ~ 5 MeV) (  g 9/2 ) 2 8+ x h 11/2 = 27/2 - (E x ~ 5.5 MeV) Allowing 4 protons in (  g 9/2 ) gives extra 4 , ie. (  g 9/2 ) x d 5/2 = 29/2 + (  g 9/2 ) x g 7/2 = 31/2 + (  g 9/2 ) x h 11/2 = 35/2 - Higher spins require N=50 core breaking. 25/2 + ? 27/2 + ? 27/2 - ? 23/2 + ? 88 Se core sen. 3 val.max. 29/2  35/2 ? Seniority 5 Val. Max ? > 35/2 N=50 core breaking

P.H. Regan 1, N.J. Thompson 1,2, A.B. Garnsworthy 1,2, H.C. Ai 2, L. Amon 2,3, R.B. Cakirli 2,3, R.F. Casten 2, C. Fitzpatrick 1,2, S.J. Freeman 4, G. Gurdal 5, A. Heinz 2, G.A. Jones 1, E.A. McCutchan 2, J. Qian 2, V. Werner 2, S.J. Williams 1, R. Winkler 2 1 Dept. of Physics, University of Surrey, Guildford, GU2 7XH, UK 2 WNSL Yale University, 272 Whitney Avenue, New Haven CT 06520, USA 3 Dept. of Physics, Istanbul University, Istanbul, Turkey 4 School of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL, UK 5 Clark University Worcester, Mass , USA