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 gammaray 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.

Automated summary

Using a sample of 47Ca produced through isotope harvesting, branching ratios for different characteristic gamma rays were measured, as well as the branching ratio for 47Ca to 47Sc beta decay and from ground state to excited state. The measurements presented greatly increased precision compared to currently accepted values.