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

TheK X-ray emission probabilityP _K ω _K for the decay of⁸⁵Sr 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 4π proportional counting in a pressurized detector and by 4π(A, X)-γ coincidence counting respectively. In addition, a high-pressure ionization chamber has been used to measure the⁸⁵Sr 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 the⁸⁵Rb daughter nucleus. A value of (1.25 ±0.05)×l0?4 was measured for the intensity of the 869 keVγ-ray relative to the predominant 514 keVγ-ray.