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AGATA@GSI LoI Relativistic Coulomb M1 excitation of neutron-rich 85 Br N. Pietralla G. Rainovski J. Gerl D. Jenkins

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Evolution of the proton SPEs towards 78 Ni Approaching 78 Ni from left - N=40 to N=50 Z=28 50 K.T. Flanagan et al., PRL 103, 142501 (2009) T. Otsuka et al., PRL 104, 012501 (2010)

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89 Y, NNDC; 87 Rb, L. Käubler et al., PRC 65, 054315; 85 Br NNDC; 83 As, NNDC and E, Sahin et al., AIP Conf. Proc. 1072, 298 (2008), 1012, 139 (2008); 81 Ga, D. Verney at al. PRC 76, 054312 (2007) 39 ESPE (kEV) 39373533 31 29 Approaching 78 Ni from above - Z=40 to Z=28 89 Y 87 Rb 83 As 81 Ga 85 Br 79 Cu ? 1)E( p 3/2 ) – E( f 5/2 ) constant 2) E( p 1/2 ) – evolves ??? 28 50 p 1/2 ???

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What is the unique experimental signature of p 1/2 ? 89 Y 87 Rb 85 Br Spin-flip M1 transitions: direct observation of spin-orbit splitting Relativistic Coulomb excitation reactions 1p (l=1) j < = l-1/2 1p 1/2 j > = l+1/2 1p 3/2 B(M1;j > j < ) 1 N 2 Unique signature!!! 0.68(10) N 2 0.47(5) N 2 ??? c (E2) (1/ ) 2 c (M1) – independent at high v/c large M1 matrix elements can significantly contribute to the total CE yield Relativistic beam energies 50-80 % Huge Doppler spread in the observed -ray spectrum need of capability to perform precise Doppler correction and reduce the Doppler broadening AGATA Unique at GSI

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Test case – 85 Br primary beam – 86 Kr with intensity of about 10 9 pps primary target – 2 g/cm 2 9 Be secondary beam – 85 Br, produced in fragmentation - 10 mb secondary beam energies – 200 MeV/u and 450 MeV/u beam intensity at S4 – 10 5 pps (10% FRS efficiency) yield estimates - 10% efficiency of AGATA+PRESPEC set-up Assume the same strengths as in 87 Kr: B(E2;5/2 - 3/2 - )= 40 e 2 fm 4 B(M1;5/2- 3/2 - )=10 -2 N 2 B(M1;1/2 - 3/2 - )=0.58 N 2 E beam (MeV/u)v/cE level (keV)JJ CE (mb)Yield ( /h) 2000.57 3455/2 - 6.94234 11911/2 - 0.6422 4500.74 3455/2 - 4.21142 11911/2 - 0.7826 Disentangle E2 and population from GDR: DSAM, two beam energies and multiplicity-total energy gates HECTOR Beam time – 100 h 85 Br

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Summary Relativistic Coulomb M1 excitation of neutron-rich 85 Br physics goal - to fix the relative spacing between the p 1/2 and p 3/2 orbitals in the neutron rich nucleus 85 Br methodological goal - to show that the method of relativistic Coulomb excitation is a reliable experimental tool for quantitative study of M1 excitation strengths in exotic nuclei Requires RIB at relativistic energies – unique at GSI Requires capability for high resolution -ray spectrometry at v/c 50-80% - needs AGATA

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