High-spin states of 39K and 42Ca

Abstract

High-spin states of 39K and 42Ca have been investigated with the 28Si( 16O, αpγ) 39K and 28Si( 16O, 2pγ) 42Ca reactions at a beam energy of 45 MeV. Gamma-gamma coincidence, γ-ray angular distribution and linear polarization measurements were performed with a Ge(Li)-NaI(Tl) Compton suppression spectrometer and a three-crystal Ge(Li) Compton polarimeter. High-spin states of 39K at E x = 7.14,7.78and8.03 and of 42Ca at E x = 7.75MeV are established. Unambiguous spin-parity assignments of J π = 11 2 −, 13 2 −, 15 2 +, 15 2 −, 17 2 + and 19 2 − to the 39K levels at E x = 5.35, 5.72, 6.48, 7.14, 7.78 and 8.03 MeV and of 6 −, 7 −, 8 −, 9 − and(8, 10) − to the 42Ca levels at E x = 5.49, 6.15, 6.41, 6.55 and 7.37 MeV, respectively, have been obtained. Further spin-parity restrictions, lifetime limits, excitation energies, branching ratios and multipole mixing ratios are reported. Discrepancies with previous J π assignments are discussed in detail.