Beta Spectrum ofCa47

A detailed magnetic spectrometer study was made of the shape of the beta-ray spectrum in the decay of ${\mathrm{Ca}}^{47}$. It was definitely established that the highest energy transition does not have a once forbidden unique shape and, therefore, that a $\frac{3}{2}+$ assignment to the ground state of ${\mathrm{Ca}}^{47}$ is not possible. The ground-state to ground-state transition of 1.979±0.005 MeV is probably from a $\frac{7}{2}-$ initial to a $\frac{7}{2}-$ final state with an abnormally high comparative half-life ($logft=8.5\mathrm{}$) possibly resulting from distortion of the ${\mathrm{Ca}}^{47}$ nucleus. Evidence was found for a beta transition to the first excited state of ${\mathrm{Sc}}^{47}$. This appears to be a twice forbidden transition from $\frac{7}{2}-$ to $\frac{3}{2}-$ with an energy of 1.486±0.010 MeV and an intensity of 1.3-1.8%. The comparative half-life for this $\Delta I=2\mathrm{}$, no transition is relatively short with $logft=9.0\mathrm{}$. The beta transition to the second excited state of ${\mathrm{Sc}}^{47}$ has an energy of 0.671±0.010 MeV. The relative intensity is 82.4% and $logft=6.0\mathrm{}$. The observations are consistent with an assignment $\frac{7}{2}-$ to $\frac{5}{2}-$. The energies of the three gamma rays that follow the decay of ${\mathrm{Ca}}^{47}$ were measured with a NaI(Tl) detector and 400-channel analyzer. The energies were found to be 1.308±0.005, 0.815±0.005, and 0.493±0.010 MeV. The half-life for the beta decay was measured in the magnetic spectrometer and found to be 4.7±0.1 days.