Bremsstrahlung in α Decay Reexamined

A high-statistics measurement of bremsstrahlung emitted in the α decay of ²¹⁰Po has been performed, which allows us to follow the photon spectra up to energies of ∼500  keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasiclassical approximation as well as with the exact quantum mechanical calculation. It is shown that, due to the small effective electric dipole charge of the radiating system, a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the α particle and the emitted photon.