Branching Ratios for the Three Most Intense Gamma Rays in the Decay of ${}^{47}$Ca

Abstract

A sample of ${}^{47}$Ca 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 ${}^{47}$Ca to ${}^{47}$Sc 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. The measurements presented here were made relative to the ingrown ${}^{47}$Sc daughter in a ${}^{47}$Ca sample and the well-established 159.4 keV gamma-ray branching ratio and the half-life for the decay of ${}^{47}$Sc. These measurements were supported by verifying that the half-lives measured from characteristic gamma-ray peaks over multiple spectra for both ${}^{47}$Ca and ${}^{47}$Sc were consistent with previously reported values. Additionally, the half-lives of both ${}^{47}$Ca and ${}^{47}$Sc 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.

13 pages, 5 figures