Angular correlation measurements on the excited states of 42Ca

Abstract

The excited states of 42Ca up to an excitation of 4.2 MeV were studied with a particle -y-ray angular correlation technique in order to measure their spin values and electromagnetic decay properties. Unique spin assignments were obtained for states at 3.25 MeV ( J = 4), 3.88 MeV ( J = 1) and 4.23 MeV ( J = 1). Possible spin values were restricted for the states at 4.00 MeV ( J = 2 or 3) and 4.11 MeV ( J = 1, 2 or 3). Gamma-ray branching and mixing ratios were measured. The mixing ratios for the transitions 2 2 + → 2 1 +, 2 3 + → 2 1 +, 2 4 + → 2 1 +, were found to be +0.09±0.08, −1.7 −0.5 +0.3 and 0.00±0.10, respectively. The results are discussed with reference to two sets of theoretical calculations, firstly those assuming an inert 40Ca core and then those considering core excitation. The core excitation model gives reasonably good agreement with the experimental results.