Interplay between single-particle and collective excitations in argon isotopes populated by transfer reactions

Abstract

New γ transitions have been identified in argon isotopes in 40 Ar + 208 Pb multiple transfer reactions by exploiting, in a fragment-γ measurement, the new generation of magnetic spectrometers based on trajectory reconstruction coupled to large γ arrays. The coupling of single-particle degrees of freedom to nuclear vibration quanta was discussed. The interpretation of the newly observed states within a particle-phonon coupling picture was used to consistently follow, via their excitation energies, the evolution of collectivity in odd Ar isotopes. The proposed level schemes are supported by the results of sd-pf shell-model calculations, which have been also employed to evaluate the strength functions of the populated states.

First in-beamγ-ray study of the level structure of neutron-richS39

“…The largest component of the wave function (33%) is π (1d 5/2 ) 6 ⊗ ν(1d 3/2 ) 4 (1f 7/2 ) 2 (2p 3/2 ) 1 . In the work of Szilner et al [44], the most strongly populated state of 41 Ar is that at 1354 keV with a J π value of 3/2 − ; this state has a pronounced single-particle character. In the 40 Ar(d,p) 41 Ar single-neutron transfer study of Sen et al [50], the measured transfer strength to the state is (2J + 1)S = 1.7 ± 0.3, which is consistent, within the normal uncertainties associated with a distorted-wave Born analysis of single-nucleon transfer cross-section measurements, with the shell-model wave function, π (1d 5/2 )…”

“…For 41 Ar, the level scheme of Szilner et al [44] is presented; in this work, the PRISMA/CLARA detector systems were used, as in the present study, and states of 41 Ar were populated in a binary grazing reaction initiated by an 40 Ar beam on a 208 Pb target. Consequently, there are expected to be some similarities with the yrast and near-yrast excited states of 39 S based on the present work; however, because the states of 41 Ar were populated in a one-neutron transfer reaction, single-neutron states are also expected to be strongly populated in this case, and this is what is observed experimentally [44].…”

Selective properties of neutron transfer reactions in the 90Zr + 208Pb system for the population of excited states in zirconium isotopes

“…In the reaction 40 Ar + 208 Pb [9], the interpretation of newly observed states within a particlephonon coupling picture has been used to consistently follow, via their excitation energies, the evolution of collectivity in odd Ar isotopes. In 48 Ca + 64 Ni [10], evidence has been found, using a weak coupling model, for particle-vibration coupled states in 49 Ca and 47 Ca based on the 3 − phonon of 48 Ca.…”

Multinucleon transfer reactions in the Ar40+Pb208 system

“…The same reaction (in the same experiment) was previously used [12,24] to study the spectroscopy of the neutron-rich Ar and Cl isotopes with PRISMA coupled with the CLARA gamma array. • .…”