High-spin states in neutron-rich Dy isotopes populated in deep-inelastic reactions

Abstract

High-spin states in neutron-rich Dy isotopes, populated in deep-inelastic processes produced by the interaction of 234 MeV 37Cl ions with a 160Gd target, have been studied using the highly sensitive EUROBALL IV gamma-ray detector array. The previously known level schemes for 159,160,161,162Dy have been extended to significantly higher spin ( ? 30?) and the i 13/2 band crossing in 159Dy has been observed for the first time. The experimental results are discussed within the framework of cranked shell model and projected shell model calculations with particular reference to the observed delayed band crossing in 162Dy

Intruder negative-parity states of neutron-richSi33

“…The neutron-rich nucleus 33 Si was populated in binary grazing reactions produced by a 215-MeV beam of 36 Projectile-like fragments produced during the reaction were analyzed with PRISMA, a large acceptance-angle magnetic spectrometer (±5.5…”

“…The evolution of the E(1/2 + )-E(3/2 + ) energy spacing for odd-mass K, Cl, and P isotopes with neutron numbers in the range from 20 to 28 has been reported by Gade et al [8]. 33 Si has previously been studied using deep inelastic collision processes with a thick target [9][10][11], in multinucleon transfer reactions [12,13], in one-neutron knockout reactions [14], and in β decay [15]. The ground-state J π value has been assigned as 3/2 + , on the basis of one-neutron transfer studies [14] and shell-model predictions.…”

“…In the work of Cottle [6], the splitting is given as about 7 MeV for 34 Si. In its ground state, 33 Si has a neutron hole in the 1d 3/2 orbit; neutron one particle-two hole configurations * zhimin.wang@uws.ac.uk will therefore play a dominant role in the structure of negativeparity states. With a neutron promoted to the 1f 7/2 orbit, the monopole tensor force [7] will influence the binding of the proton single-particle orbits below the Z = 20 shell closure.…”

“…Knowledge of the nuclear structure of 33 Si is somewhat limited, and here we attempt to address this in an experiment that utilized an experimental setup involving the coupling of the large-acceptance magnetic spectrometer PRISMA [17] and the high-granularity and high-efficiency γ -ray Ge detector array CLARA [18]. The ability to perform Doppler correction, on an event-by-event basis, of the energies of γ rays emitted by nuclei moving with velocities of the order of υ/c ∼ 0.1, together with good reaction-channel selection, enables highquality singles γ -ray spectra to be produced.…”

“…The experimental level scheme is compared with the results of 1hω p-sd-pf large-scale shell-model calculations using the recently developed PSDPFB effective interaction; good agreement is obtained. The structure of the populated states of 33 Si is discussed within the context of an odd neutron coupled to states of the 32 Si core. …”