Freiburg 1999 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 32: Postersitzung / Kernphysik

HK 32.5: Poster

Wednesday, March 24, 1999, 10:15–12:00, Foyer

Beta Decay of ⁹⁷Ag: Evidence for the Gamow-Teller Resonance near ¹⁰⁰Sn — •Z. Hu¹, L. Batist², J. Agramunt³, B.A. Brown⁴, D. Cano-Ott³, R. Collatz¹, A. Gadea³, M. Gierlik⁵, M. Górska¹, H. Grawe¹, M. Hellström¹, Z. Janas⁵, M. Karny⁵, R. Kirchner¹, F. Moroz², A. Płochocki⁵, M. Rejmund¹, E. Roeckl¹, B. Rubio³, M. Shibata¹, J. Szerypo⁵, J.L. Tain³, and V. Wittmann² — ¹GSI Darmstadt — ²PNPI St. Petersburg — ³IFIC Valencia — ⁴Michigan State University — ⁵University of Warsaw

A cube-like array of 6 Euroball-Cluster germanium detectors [1] and a total-absorption γ-spectrometer [2] were used to investigate the β decay of ⁹⁷Ag, a three proton-hole nucleus with respect to the ¹⁰⁰Sn core. Half-life and Q_EC value of the decay of the 9/2⁺ ground-state of ⁹⁷Ag were determined to be 25.9(4) s and 6.98(11) MeV, respectively. A total of 603 γ rays (578 new) was observed, and 151 levels (132 new) in ⁹⁷Pd have been identified. An interesting β-delayed γ cascade was observed, which comprises 6 γ transitions with a de-excitation pattern involving an initial increase of the level spin. The Gamow-Teller (GT) β-decay strength distributions from the two complementary measurements reveal a large GT resonance around 4 MeV with a width of about 1.8 MeV. The hindrance factor for the total GT strength, summed from the ground state up to 6 MeV excitation energy of ⁹⁷Pd, amounts to 4.2(6) with reference to the extreme single-particle shell-model prediction.

[1] Z. Hu et al., Nucl. Instr. and Meth. in Phys. Res. A, in print.

[2] M. Karny et al., Nucl. Instr. and Meth. in Phys. Res. B126, 411 (1997).