Branching ratios for the three most intense gamma rays in the decay of ⁴⁷Ca

A sample of ⁴⁷Ca produced through isotope harvesting at the National Superconducting Cyclotron Laboratory was used to measure branching ratios of 7.17(5)%, 7.11(5)%, and 75.0(5)% for the 489.2, 807.9, and 1297.1 keV characteristic gamma rays, respectively. Based on these updated branching ratios, the ground state to ground state ⁴⁷Ca to ⁴⁷Sc beta decay branching ratio has been indirectly measured as 17.7(5)% and the ground state to 1297.1 keV excited state as 82.2(5)%. These values represent a greatly increased precision for all five branching ratios compared to the currently accepted values (Burrows, 2007). The measurements presented here were made relative to the ingrown ⁴⁷Sc daughter in a⁴⁷Ca sample and the well-established 159.4 keV gamma-ray branching ratio and the half-life for the decay of ⁴⁷Sc (Reher et al., 1986; Meadows and Mode, 1968; Mommsen et al., 1980). These measurements were supported by verifying that the half-lives measured from characteristic gamma-ray peaks over multiple spectra for both ⁴⁷Ca and ⁴⁷Sc were consistent with previously reported values. Additionally, the half-lives of both ⁴⁷Ca and ⁴⁷Sc were independently measured with Liquid Scintillation Counting to reverify the previously reported values used in this study to find updated gamma-ray branching ratio values.