The electron capture decay of85Sr-measurements of theK X-Ray emission probability, half-life, and decay scheme

Abstract

The K X-ray emission probability Prmr for the decay of 8SSr has been measured to be 0.5866 with a standard error of 0.05 % and a systematic uncertainty of 0.65 %. The X-ray emission and total disintegration rates were measured by 4~z proportional counting in a pressurized detector and by 47c(A, X)-), coincidence counting respectively. In addition, a high-pressure ionization chamber has been used to measure the 85Sr half-life giving a value of 64.84 d with a standard error of 0.01% and a systematic uncertainty of 0.02 %. An investigation of the decay scheme was performed which confirmed the presence of a weak decay branch to a state at 869 keV in the 85Rb daughter nucleus. A value of (1.25 _+0.05) x 10 .4 was measured for the intensity of the 869 keV ),-ray relative to the predominant 514 keV 7-ray.

The level structure of85Rb and87Rb from (n, n??) reaction measurements

“…The SSRb nucleus lies in a transition region and exhibits a level structure more complex than that of STRb due to the two additional holes in the neutron shell. The low-lying levels of 85Rb have been studied by electron capture [20,21,22], coulomb excitation [17], single-particle transfer reactions [23,24], as well as by inelastic neutron scattering [18,19]. The present measurements, although again being in general agreement with previous data, have served to resolve several discrepancies, establish six new levels and assign more accurate level energies whilst also resolving spin assignment ambiguities in several cases.…”

“…Spin values of 1/2 and 9/2 are eliminated by the angular distribution of the ground-state transition [17]. Since it has now been definitely established that this level is populated in the 85Sr EC decay (64.84 D) from the 9/2+ 8~Sr ground state [20,21,22] with a logft value less than 11 [20], the only remaining spin possibilities are 5/2-and 7/2-, where the negative parity is implied by the E2 nature of the coulomb excitation process. In the present experiment this level is observed to decay to the 5/2-ground state, 3/2 -and 9/2 + levels leading to a definitive spin assignment of 7/2 -.…”