Testing shell-model interactions at high excitation energy and low spin: Nuclear resonance fluorescence in Ge 74

With their complex low-spin structure, the germanium isotopes have accrued a large number of experimental data which challenge nuclear models. The structure of the Ge74 isotope is investigated here with nuclear resonance fluorescence as part of an extensive campaign of experimental tests of the shell model in the germanium isotopic chain using a number of complementary techniques. Levels were excited with 3.10-5.44 MeV photon beams provided by the High Intensity Gamma-Ray Source at TUNL. Many new levels were identified and their spins, parities, branching ratios, and associated scattering cross section values were determined. Large-scale shell-model calculations, which include jj44b and JUN45 effective interactions developed to describe nuclei in this mass region, predict the new data satisfactorily. This study extends the validation of these two interactions, which are candidates for computation of matrix elements to be used in the interpretation of neutrinoless double-β decay experiments in Ge76, into the low-spin, high excitation energy domain.

Duke Scholars

Author Sean Finch  

Author Werner Tornow Physics