High-spin states in 40K investigated with the 26MG + 16O reaction

Abstract

Yrast levels in 40K and 40Ar have been investigated with the 26Mg( 16O, pnγ) 40K and 26Mg( 16O, 2pγ) 40Ar reactions at a beam energy of 34 MeV. Gamma-ray angular distribution and γ-γ coincidence measurements have been performed with a high-resolution large volume Ge(Li)-NaI(Tl) Compton-suppression spectrometer. Gamma-ray linear polarizations have been measured with a three-crystal Ge(Li) Compton polarimeter. The 40K decay scheme involves new high-spin levels at E tx = 4365.6±0.3, 4875.6±0.4 and 6227.0±0.5 keV with lifetime limits of < 1, < 1 and < 2ps, respectively. Unambiguous spin-parity assignments of J π = 5 −, 6 +, 8 +, 9 + and (8, 10) − to the 40K levels at E x = 0.89, 2.88, 4.37, 4.88 and 6.23 and of J π = 4 + and 6 + to the 40 Ar levels at E x = 2.89 and 3.46 MeV, respectively, have been obtained. Branching ratios and multipole mixing ratios are reported.