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Coulomb Excitation of Neutron-rich Isotopes around A~140 (IS 411)

Coulomb Excitation of Neutron-rich Isotopes around A~140 (IS 411). Thomas Behrens Physik-Department E12 TU München. Physical motivation: Evolution of B(E2) values around N=82. Experimental setup and realisation at REX-ISOLDE with MINIBALL. Preliminary results for 144 Xe & 124,126 Cd.

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Coulomb Excitation of Neutron-rich Isotopes around A~140 (IS 411)

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  1. Coulomb Excitation of Neutron-rich Isotopes around A~140(IS 411) Thomas Behrens Physik-Department E12 TU München

  2. Physical motivation:Evolution of B(E2) values around N=82 Experimental setup and realisationat REX-ISOLDE with MINIBALL Preliminary resultsfor 144Xe & 124,126Cd Conclusion & Outlook Gliederung

  3. Modified Grodzins’ rule Grodzins’ rule (version by Raman) Motivation [S.Raman et.al., Atomic Data and Nucl. Data Tables 78,1 (2001)] Isospin dependent modification of Grodzins’ rule Setup Results [D.Habs, R.Krücken, INTC-P-156 (2002)] Minimum mass for fixed A (from Weizsäcker’s mass formula) Outlook

  4. B(E2) values before IS411 B(E2) before 2004 122Cd Motivation Setup 140Xe ? Results 136Te Outlook

  5. preliminary results: 122Cd: 0.37(11) e2b2 124Cd: 0.32(10) e2b2 B(E2) values after 2004 B(E2) after 2004 122,124Cd Motivation Setup 140Xe Results 136Te Outlook

  6. preliminary results: 138Xe: 0.38(2) e2b2 140Xe: 0.52(2) e2b2 142Xe: 0.69(2) e2b2 B(E2) values after 2005 B(E2) after 2005 138,140,142Xe Motivation Setup Results 136Te Outlook

  7. Projectile b Z Target f i Coulomb Excitation • Beam energy below Coulomb barriera“Safe Coulex” • bproj ~ 0.06 c (aDoppler correction) Motivation Setup Results Outlook

  8. REX-ISOLDE & MINIBALL 124,126Cd(Laser Ionization) Motivation 144Xe Setup Results REX-ISOLDE Outlook MINIBALL MINIBALL

  9. Particles • Angles • Energies Gamma- spectroscopy Beam monitor Beam purity MINIBALL DSSSD PPAC Beam g Target Beam Dump Detector TU Darmstadt Univ. of Edinburgh Experimental Setup Motivation Setup Results Outlook

  10. Statistics for Cd isotopes Motivation Setup • Protons on converter target (didn’t hit the converter!) • new quartz transfer line a improved purity!! • Laser ionization (RILIS) • varying beam intensities and purities (increasing In)a problems with the ISOLDE target • tried different settings for line heating and target heating Results Outlook

  11. Statistics for Xe isotopes Motivation Setup Results • shielding to slow down ejectiles at low qlab a changed due to low energy from REX • changed target to check for scattered particlesa beam was not focused, might have hit collimator • changes of IH phase, line & target heating a improved intensity • 2h on stopper foil a looking for decay lines of 144Cs Outlook

  12. CD energy vs angle Motivation Epart [a.u.] Setup 64Zn 124Cd Results Outlook

  13. 124Cd: Eg(21+) peaks runnig time: ~15 h (Laser ON) Doppler correction incl. particle reconstruction Contaminants: 124In, 124Cs Motivation 124Cd FWHM ~12 keV Setup 64Zn FWHM ~14 keV Results Outlook

  14. 126Cd: Eg(21+) peaks runnig time: ~26 h (Laser ON) Doppler correction incl. particle reconstruction Contaminants: 126In, 126Cs Motivation 126Cd FWHM ~15 keV Setup 64Zn FWHM ~15 keV Results Outlook

  15. 144Xe: Eg(21+) peaks runnig time: ~19 h (2.7 MeV/A) Reconstruction of Recoils for Doppler correction a elastic scattered Xe to be used for normalization Motivation 144Xe FWHM ~6 keV Setup 96Mo ~25 counts Results Outlook

  16. Preliminary Results: Isotope B(E2)[e2b2] 124Cd 0.35(6) 126Cd 0.22(3) 144Xe 0.73(18) B(E2) values after 2006 126Cd 144Xe Motivation Setup Results 136Te Outlook

  17. successful measurement of 144Xe & 124,126Cda no derivation from systematic open tasks: • beam contamination • CD efficiency • angular distribution of g’s • 144Xe: normalize to Rutherford proposed: • development of BaF+ beams for Ba isotopes • 128Cd is feasible Conclusion & Outlook Motivation Setup Results Outlook

  18. dashed line: theoretical calculation[N.Shimizu et.al., Phys.Rev.Lett. 86,1171 (2001)] solid line: modified Grodzins` rule [S.Raman et.al., Atomic Data and Nucl. Data Tables 78,1 (2001)] Future Experiments Ba isotopes Motivation 150Ba ? Setup 140Ba 148Ba Results Outlook Mass Number

  19. Helping hands and heads... T. Behrens1, V. Bildstein1, R. Gernhäuser1, Th. Kröll1, R. Krücken1, M. Mahgoub1, P. Maierbeck1, W. Weinzierl1, D. Habs2, R. Lutter2, T. Morgan2, P. Thirolf2, F. Finke3, M. Seidlitz3, N. Warr3, D. Weisshaar3, S. Franchoo4, J. Diriken5, P. van Duppen5, O. Ivanov5, I. Stefanescu5, J. van de Walle5,6, J. Cederkall6, L. Fraile6, U. Köster6, T. Sieber6, D. Voulot6, F. Wenander6, A. Ekström7, T. Davinson8, and the REX-MINIBALL collaboration 1TU München, 2LMU München, 3Universität zu Köln, 4IPN Orsay, 5KU Leuven, 6CERN, 7Lund University, 8University of Edinburgh, Thank you for your attention!

  20. MINIBALL NEW: 3 MeV/A Targets 0 5 10 m REX-ISOLDE @ CERN ISOLDE Thomas Behrens

  21. IS411 – Intensity on CD Hits on CD in polar coordinates Motivation Setup y [mm] Results x [mm] 96Mo(144Xe,144Xe)96Mo: Beam shift: ~2 mm Outlook

  22. Modified version (Habs, Krücken, INTC-P-156 (2002) ) B(E2)exp / B(E2)theo Physical Motivation Empirical relation between E(2+) and B(E2) [Grodzins’ Rule] (N.V. Zamfir et.al., Phys.Rev.C 51 (1995) 98 ) B(E2) smaller than expected

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