Circular Polarization of Internal Bremsstrahlung

Abstract

A calculation is made of the circular polarization of the internal bramsstrahlung in allowed $\ensuremath{\beta}$-decay with the most general $\ensuremath{\beta}$-interaction. The polarization is found to rise from zero at the low-energy end of the spectrum to a maximum value at the high-energy end. This maximum value depends critically on the relative magnitudes of the coupling constants in the $\ensuremath{\beta}$-interaction. With the two-component neutrino theory and only the scalar and tensor interactions present, the polarization is complete at the high-energy end of the spectrum. Plots have been made, with this $\ensuremath{\beta}$-coupling, of the Born approximation result for the circular polarization as a function of photon energy for ${\mathrm{S}}^{35}$ and ${\mathrm{P}}^{32}$. The effects of the nuclear Coulomb field on the $\ensuremath{\gamma}$-ray spectrum and polarization are discussed.