KCapture to Positron Ratio forNa22

Abstract

The ratio of electron capture to positron emission from ${\mathrm{Na}}^{22}$ to the 1.28-Mev excited state of ${\mathrm{Ne}}^{22}$ has been measured by determining the relative number of 1.28-Mev and 0.511-Mev gamma rays from this decay. The gamma-ray intensities were measured with a 4-in. by 4-in. NaI(Tl) scintillation spectrometer and a collimated geometry. Photopeak areas were determined for the two gamma-ray energies, and using photopeak to total areas previously determined and NaI absorption coefficients, the ratio of gamma-ray intensities was calculated. The results showed that 11.0±0.9 percent of the disintegrations to the excited state of ${\mathrm{Ne}}^{22}$ are not accompanied by the emission of two 0.511-Mev quanta, and therefore decay by orbital electron capture.