High spin states in75Se populated by the72Ge(?,n) and73Ge(?, 2n) reaction

Abstract

Abstract. The 72Ge(~, n)75Se and 73Ge(0~, 2n)75Se reactions have beer studied at bombarding energies of 15 MeV and 22.5 MeV respectively using Ge(Li)-detectors. 7-singles spectra, 7-7-coincidences, ";-angular distributions and excitation functions have been taken. A level scheme has been constructed, which contains a stretched spin and a normal rotational band. Nuclear reactions ~2Ge(~,n)VSSe, 73Ge(c~,2n)75Se; measured E., I~, ~'-7-coincidences, 7-angular distribution, 7-excitation function. 75Se deduced levels, J, 7t, 7-multipolarity. Enriched target, Ge(Li).

High spin states in73Se observed by the reaction70Ge(?,n?)

“…Similar bands have been found in odd isotopes of which we investigated 71As [4,5], 73As [5,6], 8tRb [7,8], 83Rb [9], VSSe [10], VVSe [11] and 79Se [12]. For extending our survey on the odd Se isotopes we used the reaction 7~ to populate the high spin states of the 73Se nucleus.…”

“…This is the reason why we assign the spin (5/2) to this level. We think that it should have positive parity, as in 7SSe and 77Se there is also a low lying 5/2 + state [10,11], but we cannot proof that.…”

“…We assign to it tentatively a spin of 1/2 or 3/2 as the excitation function of the 64.9keV line is among those increasing most slowly even if one compares it with the sidefeeding of other levels. In 758e, 77Se and 79Se there exists a low lying 1/2-state [10][11][12], which might correspond to this level. Figure 6.…”

“…For extending our survey on the odd Se isotopes we used the reaction 7~ to populate the high spin states of the 73Se nucleus. After we gave a preliminary account on the negative parity cascade found in this nucleus [13], Behar et al [14] reported also the lowest five states of this cascade which they populated by the 72Ge(~, 3n7) reaction. 738e was investigated before by means of the 7-spectroscopy only by Murray et al [15] who produced it by the/?-decay of 73Br.…”

Rotational bands in77Kr

“…In this case decoupling is favoured by the high angular momentum of the positive parity neutron (gg/z), but hindered by the rather large deformation of the core. The energies of this cascade are very similar to those of the positive parity band in ~45Se~1 [17]. Summing up one can say that the (3/2) band can be described as a case of strong coupling in the sense of Bohr and Mottelson with some slight perturbation, whereas the 5/2 + band is closer to the rotation aligned coupling scheme of Stephens.…”