The polarization of the beta rays from five negatron emitters has been studied by the method of Møller scattering in a magnetized NiFe foil. The scattered incident electron and the recoil electron from the target foil are detected in coincidence by two scintillation counters. The difference between the coincidence counting rates for the two directions of foil magnetization divided by the average rate gives a quantitative measure of the longitudinal polarization of the incident beta rays. Our experimental results are as follows: ${\mathrm{P}}^{32}$, $P=-(0.94\mathrm{}\pm 0.06)\frac{v}{c}$; ${\mathrm{Y}}^{90}$, $P=-(0.86\mathrm{}\pm 0.06)\frac{v}{c}$; ${\mathrm{Pr}}^{144}$, $P=-(0.90\mathrm{}\pm 0.22)\frac{v}{c}$; ${\mathrm{Au}}^{198}$, $P=-(0.98\mathrm{}\pm 0.18)\times \frac{v}{c}$; and for RaE, $P=-(0.69\mathrm{}\pm 0.10)\frac{v}{c}$. The first four results may indicate a polarization magnitude slightly less than full $-\frac{v}{c}$. The differences are, however, within the range of possible systematic errors. The result obtained with RaE is significantly lower than the average of the other four results. This indicates a departure from $-\frac{v}{c}$ polarization for this nuclide.

• Received 11 August 1958

DOI:https://doi.org/10.1103/PhysRev.112.1684