Shape determination in Coulomb excitation of 72 Kr

1. B.S. Nara Singh University of York Shape determination in Coulomb excitation of 72Kr Oblate shape driving mechanism rp-processes in X-ray binaries

2. Shape co-existence in A=70 region; expected for Kr, Se isotopes W. Nazarewicz et al., NPA 435 (1985) 397 36

3. Present Scenario • Moments of inertia, B(E2) values on 68Se,72Kr • →oblate low-lying and prolate high-lying states • S. Fischer et al., PRC 67, 064318 (2003), PRL 84, 4064 (2000) • A. Gade et al., PRL 95, 022502 (2005) • Coulomb energy differences,70Se,70Br • →prolate (2=0.18) to prolate (0.33) shape change • B.S. Nara Singh et al., Submitted to PRC Rapid com. • Re-orientation effect in low energy Coulex on70Se • →prolate 2+state for 70Se • A.M. Hurst et al., PRL 98, 072501 (2007) • No excited 0+ state found in 68, 70Se • No direct evidence for oblate ground/low-lying states

4. Electron and -spectroscopy E. Bouchez et al, PRL 90, 082502 (2003) Y.Sun et al, NPA 758 (2005) 765

5. Intermediate energy Coulomb excitation A. Gade et al., PRL 95, 022502 (2005) 72Kr: All evidence points towards oblate ground/low-lying state

6. Coulomb excitation E. Clément et al, to be published in PRC Reproduced by triaxial HFB with Gogny DIS interaction

7. A. Gade et al., PRL 95, 022502 (2005) ~ 28 % reorientation effect Population due to M12 gives magnitude of β M22 gives sign of β as well ~ 2% variation in the 2+ state population due to depletions 72Kr 104Pd

8. 70Se at 2.94 MeV/u on 104Pd A.M. Hurst et al PRL 98, 072501 (2007) 139 (13) 22 % 540 (40) ~ 11 % cross section measurement, relative to 104Pd → 6 % accurate experimental B(E2) value for 104Pd

9. 72Kr at 3.0 MeV/u on 104Pd M02 < 0.70 eb Rotational value for M22 B(E2: 0+→2+) = 0.4997(647) e2b2 A. Gade et al., PRL 95, 022502 (2005) ?? ~ 26%

10. Beam time request Assumptions CD coverage: 16.2 to 53.3 εγ= 7% at 1.3 MeV 76kr at 3-3.1 MeV/u, ~106 pps at target position for 1+1 days

11. 72Kr at 200 MeV 104Pd 2mg/cm2 CD coverage: 16.2 to 53.3 εγ= 7% at 1.3 MeV

12. Collaboration B.S. Nara Singh, D. G. Jenkins, C. J. Barton, M. Bentley, M.J. Taylor, R. Wadsworth , Univ. of York, UK. J. Cederkall, E. Clément, P. Delahaye, L. M. Fraile , J. Lettry, F. Wenander, ISOLDE P. Van Duppen, K.U. Leuven, Belgium R. Krücken, Technische Universität München, Germany P. Reiter, University of Cologne, Germany N. Pietralla, Technische Universität Darmstadt, Germany A. Görgen, W. Korten, M. Zielinska, CEA-SACLAY, DSM/DAPNIA/SPhN, France P.A. Butler, R.-D. Herzberg, R.D. Page, E.S. Paul and A. Petts, University of Liverpool, UK J. Billowes, C.R. Fitzpatrick, S. J. Freeman, University of Manchester, UK R. Chapman, X. Liang, J. Ollier, J. F. Smith, University of Paisley, UK P.J. Woods, University of Edinburgh, UK D. Bandyopadhyay, TRIUMF, Canada K.Heyde, S. de Baerdemacker, V. Hellemans, Ghent University, Belgium P.-H. Heenen, Université Libre de Bruxelles, Belgium M. Bender, CNRS/IN2P3, Centre d'Etudes Nucléaires de Bordeaux Gradignan, France and the Miniball collaboration and the REX-ISOLDE collaboration Spokesperson: B.S. Nara Singh Contactperson: E. Clément

13. Thanks

14. 2+2 R * 1.61 b R* 3.40 b + (1-R) * 1.94 b 2+1 0+2 Intermediate energy Coulex; Isomeric ratio R unknown for 02 B(E2) = 0.4997(647) e2b2 A. Gade et al., PRL 95, 022502 (2005) 2+2is not observed → R <<1 and ~ 5% > 26% B(E2) gets reduced by ~ 5% No effect on sign determination

15. The case of 72kr ~ 1 % uncertainty in the 2+ state population due to this depletion An over estimated coupling, 0.70 eb →

16. Unlikely ?? M22 < < M02 Likely !! M22 > M02 M22 > 0.71 eb , M02 < 0.71 eb

17. Unlikely Assumed M02 ~ 0.70 eb Rotational value for M22 M22 < < M02 →Second 2+ would be observed → Re-orientation effect and the depletions at similar levels. → More accurate B(E2) value An independent B(E2) value + Angular distributions → determination of the shape Interpretation may have to be done for two possible scenarios ??.