A simplified response function formalism for medium-heavy Λ hypernuclei

There is a variety of spectra for Λ hypernuclei (from light to heavy) which contain many peaks ranging from the deepest orbits to the surface ones. An approach is presented for the calculation of the bound state specrum of Λ hypernuclei, where the cross section is expressed through the response function. This was achieved in the framework of the Green function method with a square well optical potential using the plane waves. An analytic treatment was made for the prominent peaks with the contribution of only the valence neutron-hole series and a Gaussian folding was obtained for the rest spectrum. The method was applied mainly to the (π+,Κ+) medium to heavy Λ hypernuclei and also to the (Ä"~in-flight, π~) Λ hypernuclear spectra (with respect to their differences). The results are satisfactory compared to the experimental values. The main advantage of the proposed model is its simplicity. Possible extensions and improvements of this method are also suggested.

Excited quasiparticles and entropy in 161,162Dy

In this paper, the nuclear level densities of [Formula: see text]Dy is studied by the use of a microscopic theory which includes nuclear pairing interaction. It is based on the modified harmonic oscillator model according to the Nilsson potential. The entropy of even–odd and even–even nuclei as a function of nuclear temperature is obtained. The entropy excess of [Formula: see text]Dy is compared with that of [Formula: see text]Dy. It is concluded that the difference is related to the entropy carried by the neutron hole coupled to the even–even core. The numbers of excited quasiparticles are calculated. Good agreement was observed between calculated results and the experimental data.

Systematics on the low-lying spectra in N = 78 ~ 80 isotones

Combining the new spectroscopy results of 144 Tb and previous spectroscopy studies of neighboring nuclei, a systematic investigation on the low-lying spectra in N = 78 ~ 80 isotones is performed. Good systematics have been found for the coupling patterns which couple the odd nucleon(s), such as πh11/2, [Formula: see text], to the 2+, 4+, 6+ and 3- core excitations. It is found that the relative excitation energies of the states formed by coupling h11/2 proton(s) to the 2+, 4+ core excitations are pushed up, in contrast with those formed by coupling h11/2 neutron hole(s) to the 2+, 4+ core excitations, which are pulled down. According to the systematics, the interpretation that the 17/2+ states observed in 141 Sm and 143 Gd are the fully aligned member of coupling the odd h11/2 neutron hole to the octupole 3- core excitation, is explored to the isotones 145 Dy , 142 Eu , and 144 Tb .