Lifetime measurements in⁴²Ca (populated in²⁸Si(¹⁶O,2p))

A collective model description of the low lying and giant dipole resonant properties of40,42,44,46Ca

“…1, the ground states of 42Ca and 44Ca belong to the 'spherical' and soft prolate minima respectively. The positions of the 2[, 41+ and 61+ levels of 42'44'46Ca have been satisfactorily accounted for with conventional shell model calculations using effective two-body interactions assuming an inert 4~ core and predominantly lf7/2 and 2p3/2 neutrons [4,15]. However enhanced E2 transition rates (noteably the 2/~0i ~ transition) have warranted the inclusion of deformed components (specifically 4p-2h in 42Ca [16,17] and 6p -2h in 44Ca [18]) in the wave functions of these members of the ground state band in 42.4~Ca" Similarly the 03 and 2~-levels missing in this description have been interpreted as Core excited levels in analogy with the excited states (specifically the 0 5 and 21 + levels) of 4~ [4,5]; these deformed states arise mainly from a two-proton excitation from the sd-to p f-shell [19,20].…”