Nuclear level densities and spin cut-off factors deduced from microscopic theory for nuclei from²⁰F to²⁴⁴Am

Abstract

The experimental nuclear level densities and spin cut-off factors for nuclei from '9to '"Am are compared with a microscopic theory which includes the nuclear pairing interaction. Single particle levels of Nilssan and Seeger give similar results in most cases and both sets of single particle levels Rive results which agree well with experiment. For the case of the actinide nuclei and the lanthanide nuclei deformed single particle levels of Nilsson el ol are utilized. It is found that the values of p ( E * ) and o(E') are very sensitive to the structure of the single particle levels and the effects of this structure are illustrated and discussed. The calculational procedure is developed to account for an odd particle system blacking, this procedure as well as the effects of such blocking will also be discussed.NUCLEAR STRUCTURE study of nuclear level densities and spin cut-off factor, comparisotr of the thcorclical level densities with experiment far 20 S A S 244.

Pairing correlations and thermodynamical quantities inMo96,97

“…We have taken into account this by reducing the ground state for nuclear pairing. For information on this procedure see [20,24].…”

“…On the same figure the results from the Fermi-gas model [28] are also shown for comparison. The level density parameter is taken to be a = A/9, where A is the mass number [24].…”

“…The structural change in the entropy curves can be interpreted as a signature of the transition from strongly paired states at low temperature to unpaired at higher temperature. The dashed line on the figure represents the Fermi-gas values with the level density parameter a = A/9 [24]. Examination of Figs.…”

“…The standard theory of pairing as applied to excited states is based on the grand partition function obtained from the BCS Hamiltonian [18][19][20][21][22][23][24]:…”

Nuclear Level Densities with Microscopic Statistical Method Using a Consistent Residual Interaction

“…(6), which is a socalled renormalization term, are traditionally omitted in the BCS calculation, because its effect can be renormalized to the single-particle energies. Most of the microscopic statistical calculation 26,[37][38][39] uses Eq. (6) without the renormalization term.…”