Predrag Miocinovic

Cosmic-ray history derived from the 54Mn, 56Ni and 144Pm chronometers

Sources of 54 Mn, 55 Ni, and 144 Pm were placed at the center of the Gammasphere array and searches were made for the astrophysically interesting β + decay modes of these isotopes. The results of these searches are presented and the implications for cosmic-ray physics are discussed.

Lifetime of the 6{sub 1}{sup +} state in {sup 144}Nd

Using a comparative delayed coincidence technique the lifetime of the 6{sub 1}{sup +} level in {sup 144}Nd has been measured as {tau}=30{+-}3 ps, leading to a B(E2;6{sub 1}{sup +}{yields}4{sub 1}{sup +}) value of 25{+-}3 W.u. This value is almost a factor of 3 less than that expected for a purely collective three-phonon state, but is in agreement with particle-core coupling calculations that predict significant noncollective L=4 and L=6 components in the 4{sup +} and 6{sup +} yrast state wave functions.