RECOIL DISTANCE HALF-LIFE MEASUREMENTS OF THE EXCITED-STATES IN SM-145

A recoil distance method was used to measure half-lives of the excited states of Sm-145. The reaction used was La-139(B-10, 4n)Sm-145. A plu nger system was used. Half-lives were determined for two excited state s for the first time. The yrast 27/2(+) state was found to have a half -lifo of 1.1 +/- 0.2 ns corresponding to the retardation of 3.1 x 10(- 4) comparing with the single particle estimate of M1. The excitation e nergy of this state was well reproduced bg the shell model calculation having; a mixed configuration of [pi{h(11/2)(g(7/2))(-2) (d(5/2))(-1) }(10)-, nu f(7/2)] + [pi{h(11/2)(g(7/2))(-1)}(9)-,nu h(9/2)]. Another. retarded El transition was also found in a decay of a 21/2(+) state. Its retardation was 1.6 x 10(-4) comparing with the single particle va lue.