Collective structure of negative parity states in42Ca

Abstract

Proton- gamma ray angular correlations and Doppler shifts have been measured in the 39K( alpha ,p gamma ) reaction at Ealpha =14 and 15 MeV. Spin-parity assignments and lifetimes were obtained for the following levels: Ex=6140 keV, Jpi =6-, tau =70-20+30 fs; Ex=4896 keV, Jpi =5-, tau =64+or-30 fs; Ex=4353 keV, Jpi =4-, tau =550+or-150 fs; Ex=4099 keV, tau =730-110+140 fs; Ex=4045 keV, tau =250+or-85 fs. A total of five enhanced E2 transitions has been observed from these levels. The results are interpreted in terms of collective models.