The Beta-Spectra of Cs137, Y91, Pm147, Ru106, Sm151, P32, and Tm170

Abstract

The beta-spectra of ${\mathrm{Cs}}^{137}$, ${\mathrm{Y}}^{91}$, ${\mathrm{Pm}}^{147}$, ${\mathrm{P}}^{32}$, ${\mathrm{Ru}}^{106}$, ${\mathrm{Tm}}^{170}$, and ${\mathrm{Sm}}^{151}$ have been investigated using a large double-magnetic lens spectrometer. The investigation of these materials was carried out with sources whose thicknesses were less than 0.1 mg/${\mathrm{cm}}^2$. The sources were mounted on thin foils in such a manner that they did not accumulate charge. ${\mathrm{Cs}}^{137}$ and ${\mathrm{Y}}^{91}$ were found to have distinctly non-linear Fermi plots. ${\mathrm{Ru}}^{106}$, ${\mathrm{Pm}}^{147}$, and ${\mathrm{Sm}}^{151}$ have linear Fermi plots, and the Fermi plot of ${\mathrm{Tm}}^{170}$ is slightly curved. ${\mathrm{P}}^{32}$ had an unusual Fermi plot at the low energy end. Auger electrons have been found associated with the ${\mathrm{Ba}}^{137}$ decay product of ${\mathrm{Cs}}^{137}$, and the internal conversion electrons have been found accompanying the continuous beta-radiation from ${\mathrm{Tm}}^{170}$. The energy of the gamma-ray giving rise to the ${\mathrm{Yb}}^{170}$ conversion electrons is 85.4±0.6 kev. The end points of the continuous beta-spectra of these materials have been determined as follows: Low energy group of ${\mathrm{Cs}}^{137}$, 0.523±0.004 Mev; ${\mathrm{Y}}^{91}$, 1.56±0.010 Mev; ${\mathrm{Tm}}^{170}$, 0.990±0.007 Mev; ${\mathrm{Sm}}^{151}$, 0.0755±0.0010 Mev; ${\mathrm{P}}^{32}$, 1.718±0.01 Mev; ${\mathrm{Pm}}^{147}$, 0.229±0.001 Mev; ${\mathrm{Ru}}^{106}$, 0.0392±0.0003 Mev.