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Quadrupole collectivity in neutron-rich Cd isotopes Thorsten Kröll for the IS411/IS477/IS524 collaborations Work supported by BMBF (Nr. 06DA9036I and 05P12RDCIA),

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Presentation on theme: "Quadrupole collectivity in neutron-rich Cd isotopes Thorsten Kröll for the IS411/IS477/IS524 collaborations Work supported by BMBF (Nr. 06DA9036I and 05P12RDCIA),"— Presentation transcript:

1 Quadrupole collectivity in neutron-rich Cd isotopes Thorsten Kröll for the IS411/IS477/IS524 collaborations Work supported by BMBF (Nr. 06DA9036I and 05P12RDCIA), EU through EURONS (No. 506065) and ENSAR (No. 262010), HIC for FAIR, and the MINIBALL/REX-ISOLDE

2 1-6 June 2014 | ARIS 2014 - Tokyo | Institut für Kernphysik, TU Darmstadt | Thorsten Kröll | 2 Region of interest  Z=48 Cd 132 Sn Z=50Z=50 Sn N=82 122,123,124,126,128 Cd r process 

3 1-6 June 2014 | ARIS 2014 - Tokyo | Institut für Kernphysik, TU Darmstadt | Thorsten Kröll | 3 Neutron-rich Cd isotopes *T. R. Rodríguez et al., Phys. Lett. B668, 410 (2008) E(2 + ) drops from 126 Cd to 128 Cd! Not reproduced by SM Beyond Mean Field* approach with Gogny D1S force angular momentum projection particle number projection configuration mixing (GCM)  trend of E(2 + ) reproduced E(2 + ) somewhat too large 128 Cd is prolate deformed!?! Data: nndc.bnl.gov W. Watanabe et al., PRL 111, 152501 (2013)

4 1-6 June 2014 | ARIS 2014 - Tokyo | Institut für Kernphysik, TU Darmstadt | Thorsten Kröll | 4 Experimental set-up MINIBALL DSSSD MINIBALL Beams from REX-ISOLDE @  2.85 MeV/u “Safe” Coulomb excitation Gamma – particle coincidences Isobaric beam contaminants 24 6-fold segmented HPGe detectors (  ≈ 7%) fully digital electronics N. Warr et al., EPJ A 49, 40 (2013)

5 1-6 June 2014 | ARIS 2014 - Tokyo | Institut für Kernphysik, TU Darmstadt | Thorsten Kröll | 5 Prompt  -ray spectra NEW Analysis of 128 Cd/ 128 In: Sabine Bönig (PhD thesis, TU Darmstadt, 2014) 646 keV is indeed the 2 +  0 + transition in 128 Cd!!! Coulomb excitation of isobaric In contamination - level scheme of 126 In needs revision A. Scherillo et al., PRC 70, 054318 (2004) - new SM calculations agree with finding (G. Simpson, UWoS) - conversion electron measurement (August 2013 @ ILL)... analysis ongoing

6 1-6 June 2014 | ARIS 2014 - Tokyo | Institut für Kernphysik, TU Darmstadt | Thorsten Kröll | 6 Analysis procedure “safe” Coulomb excitation... single step dominates reorientation effect.... quadrupole moments 2+2+ 0+0+

7 1-6 June 2014 | ARIS 2014 - Tokyo | Institut für Kernphysik, TU Darmstadt | Thorsten Kröll | 7 Maximum likelihood fit Lifetime measurement with DSAM find optimal M 20 -M 22 combination if available, additional information like lifetimes is included projection of 1  contour on axes Michael Thürauf (Master thesis, TU Darmstadt) without 

8 1-6 June 2014 | ARIS 2014 - Tokyo | Institut für Kernphysik, TU Darmstadt | Thorsten Kröll | 8 New beyond mean field calc‘s Beyond mean field including triaxiality prolate deformation (  ≈ 0) excitation energies better reproduced large overlap of wave functions... large B(E2) Tomás Rodriguez (TU Darmstadt)

9 1-6 June 2014 | ARIS 2014 - Tokyo | Institut für Kernphysik, TU Darmstadt | Thorsten Kröll | 9 Collectivity in even Cd isotopes   122,124,126 Cd S. Ilieva et al., PRC 89, 014313 (2014) experimental B(E2) value for 128 Cd robust (different conditions in analysis) general trend for even Cd isotopes continued - larger B(E2)’s than SM prediction - B(E2)’s well reproduced by BMF - very limited sensitivity to Q 2 

10 1-6 June 2014 | ARIS 2014 - Tokyo | Institut für Kernphysik, TU Darmstadt | Thorsten Kröll | 10 123 Cd – first odd Cd isotope DC wrt projectile DC wrt target recoil Coulomb excitation of both 123 Cd and 123m Cd Level scheme of 123 Cd well known in literature...??? Anna-Lena Hartig (Master thesis, TU Darmstadt, 2014) (unresolved multiplet )

11 1-6 June 2014 | ARIS 2014 - Tokyo | Institut für Kernphysik, TU Darmstadt | Thorsten Kröll | 11 123 Cd – revised level scheme 466 412 222 598 Excitation energy of isomer: 144 keV (not 316 keV) A. Kankainen et al., PRC 87, 024307 (2013) Matrix elements, e.g. 117 keV: 0.92 eb 376 keV: 0.50 eb... similar size 376 117 Inconsistencies with literature H. Huck et al., PRC 40, 1384 (1989)... revised level scheme (... mainly single-step excitations!!!) -  -ray yield following Coulomb excitation -  coincidences... very few - variation of 123 Cd/ 123m Cd content in beam (RILIS, only broad band laser available for this run)

12 1-6 June 2014 | ARIS 2014 - Tokyo | Institut für Kernphysik, TU Darmstadt | Thorsten Kröll | 12 Summary and Outlook Safe Coulomb excitation of even neutron-rich isotopes 122,124,126,128 Cd... B(E2) values are larger than predictions from large scale SM calculations... better agreement with BMF... axially symmetric shapes... no clear conclusion from Q 2 (2 + ) values... small deformation preferred First successful run with odd isotope 123 Cd... level scheme needs revision... new decay experiment desirable... both positive and negative parity orbitals seem to contribute similarly to collectivity Continuation of programme at HIE-ISOLDE... multiple Coulomb excitation... lifetime measurements with plunger... 130 Cd (... worth a try at HIE-ISOLDE?)... narrow band laser to ionise selectively g.s. or 11/2 - isomer in odd isotopes... transfer reactions to pin down single-particle properties and thank you for your attention!!!!


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