Shape evolution in neutron-rich Zr isotopes through secondary fragmentation reaction

1. Shape evolution in neutron-rich Zr isotopes through secondary fragmentation reaction S. Pietri, J. Gerl et al. (GSI Darmstadt), A. Bruce et al. (Univ. Brighton), Z. Podolyak et al. (Univ. Surrey), A. Algora et al. (IFIC Valencia), D. Sohler et al. (Debrecen) presented at AGATA Physics Workshop 2010 Istanbul, Turkey May 6, 2010

2. Shape evolution in neutron rich nuclei • How to explain collective phenomena from individual motion? • What are the phases, relevant degrees of freedom, and symmetries • of the nuclear many-body system? • Investigate the evolution of shapes and shape changes in nuclei • Neutron-rich medium heavy nuclei are predicted to exhibit dramatic shape effects

3. Nuclear shapes rapid shape changes and shape coexistence octahedral nuclear shapes phase transitions of the equilibrium shapes

4. Most dramatic shape changes in heavy Zr nuclei rapid deformation change from ≈ 0.1 to  = 0.47

5. Rapid shape changes in medium heavy nuclei from spherical via triaxial to prolate deformed rigid rotor vibrator

6. Liquid drop with shell correction Shape coexistence in heavy Zr nuclei? Alignment of g9/2 protons and h11/2 neutrons produce oblate structure Hartree-Fock Bogolyubov prolate PES for 106Zr: triaxiality oblate 9/2-[514]  5/2+[420] K = 5- ~100 ns isomer

7. Rotor Vibrator X(5) Deformation X(5) Critical point nuclei Interacting Boson Model X(5) Dynamical symmetry shape transitional nuclei unexplored Sr to Mo region

8. new hmark b h n hange whic shap a enc the e c oin as against uclear of t b compared prop can e erties [3]. The symmetri from deformed a a the oin to spher- rotor transition cally of critical-p t Bohr v harmonic denoted the the X(5), e as olv solution vibrator, in es collectiv of ically w comp p an onen Hamiltonian a o with decoupled oten square that to innite in t ts tial is - w p p and quadrup harmonic a oten deformation parameter, oten the in ole tial tial ell , w y an appro This ximation deformation parameter, the the true of for triaxialit ell is . IBM p p hange from shap found oten the the Sev- e c at oin calculations of t critical tial [3]. n p b v ha X(5) examples een the suggested e to oin including close eral uclei of t critical w N=90 Ho 126 130 Ba Ce some and and ev not the the predicted [10{ er isotones, of 12]. all and y X(5) duced a the the c repro are description haracteristics applicabilit of of is still debate considerable topic of [13]. Shape evolution controversy? prolate prolate oblate shape change sudden deformation triaxial shapes shape coexistence multi quasi-particle states dynamical symmetries excited states known no excited states known ... Ideal testing ground for theoretical models m The Pro- region Figure in states predicted this cation ulti-quasiparticle of 1: lo [1]. m m 110 112 114 and Zr ; ; predicted are oblate in states ulti-quasiparticle ulti-quasiparticle late N=66 100 112 The n marks from Pd. en Se ev red the en-ev to in limit states uclei of line n h b v ha whic ed een observ e excited text in (see states uclei for details). p n and mean-eld shap used oten the the the e implications to uclear calculate for tials m used the conguration-constrained to calculations calculate ulti-quasiparticle states. p n X(5) oin 2.2 Critical t uclei. n b Benc hmarks harmonic eha the e viour are vibrator de- uclear axially collectiv of [6], They and ond formed the corresp to teracting rotor rotor in limits triaxially of soft [7], [8]. w mo (IBM) b b and an een oson nature the the description del algebraic transition et of of b dev ed een with phase has analogy these elop in direct transitions limits classical [9]. b h nd Recen an xima- a appro een approac has suggested that to analytic useful tly it is , p the tion of critical A p b pap X(5) eha a out ted recen that that necessary condition viour oin er for t [4] is w um n b b v and sucien een neutrons induce the protons alence to teractions er in et of t is n b push but not the e c so as to ucleus to rotational large haracteristics collectiv e- full P= Np Nn NpNn/(Np+Nn) and ha where This the reected P-factor viour. in [14] is um n b v and y Substan the protons neutrons, are alence resp ely ectiv ers of collectivit tial .

9. Proposed experiment Goal:Identify low and medium spin yrast and near-yrast states in 104-108Zr, and in surrounding n-rich Sr and Mo isotopes, and determine lifetimes Technique:secondary fragmentation, relativistic DSAM Beam:238U at 750 AMeV, 4x109/spill → 110Mo at 150 AMeV, 7x102/spill Set-up:AGATA ( detection) LYCCA (channel identification)

10. secondary fragmentation of 55Ni on 9Be at 140 AMeV 2+ 50Cr 4+ 6+ (8+) DSAM lineshapes Rates An example of Mikes run from the early RISING days without mass selection

12. Prefragment Equilibrated nucleus Relativistic Coulomb excitation / fragmentation 112Sn →Au Coulomb interaction excited nucleus

13. massive fragm. I (hbar) 20 30 10 High Spin population in massive fragmentation Fragmentation of 208Pb Fragmentation of 238U Isomeric ratios I R [%] 211Fr 29/2+ 5.7 (2) 212Fr 15- 7.5 (2) 213Fr 29/2+ 12.0 (8) 214Ra 17- 6.8 (2) 215Ra 43/2- 3.1 (6) 148Tb I = 27+ R = 3.2 (3) % Zs. Podolyak et al.

14. dE Ni Co Fe 2+ 50Cr Mn 4+ Cr 6+ Ti (8+) Ca Ar S Si E Secondary fragmentation of 55Ni on 9Beat 140 MeV/u Mirror symmetry at N  Z extract lifetimes from lineshapes Mike Bentley et al. 2+ 46Ti 4+ 6+ (8+) First observation of higher spin states at relativistic energies