Development of multichannel time scaling technique to analyse the half-life of 75mAs using correlation analysis

We report on the use of a multichannel time scaling technique suitable for determining the half-life of long-lived intermediate states by means of correlation counting. Use of the method is demonstrated by studying the decay of an isomer of 75As at 304 keV excitation energy using a pressurized proportional counter and NaI(Tl) detection set-up. The measurement time was 9000 s. Eighteen values for electron capture detection efficiencies were obtained in the energy region 1.4-12 keV. We obtained eighteen sets of data for determining the fraction of correlation events, each set consisting of 52 counting distributions determined by scanning the clock-time of electron capture events with dwell times varying from 5 ms to 1500 ms. There are four sets acceptable for this work according to our criteria. The half-life of the 304 keV level was determined to be (17.62±0.23) ms and is compared with earlier results. (author)