High-spin yrast levels of 38Ar

Abstract

High-spin states of 38Ar have been studied with the 35Cl(α, pγ)38Ar reaction at Eα = 18 MeV and with the 24Mg(16O, 2pγ)38Ar reaction at E(16O) = 38 and 45 MeV. The 38Ar level scheme is obtained with the former reaction from a proton-γ coincidence measurement. Gamma-gamma coincidence, γ-ray angular distribution and linear polarization experiments have been performed with a Ge(Li)-Na(Tl) Compton suppression spectrometer and a three-crystal Ge(Li) Compton polarimeter. Unambiguous spin-parity assignments of Jπ = 7−, 7+, 8 +, 7−, 9− and 11−to the 38Ar levels at Ex = 7.51, 8.08, 8.57, 8.97, 10.17 and 11.61 MeV, respectively, are obtained. The 8.57 MeV, 8+ level has a mean life below 0.8 ps. Excitation energies, branching ratios, multipole mixing ratios and transition strengths are reported. The experimental results are compared with shell-model calculations.