Bremsstrahlung emission in alpha-decay of Po-210

Bremsstrahlung photons associated with the alpha-decay of Po-210 were measu red in alpha-gamma coincidence measurements with Si and Ge detectors. Emiss ion probabilities of the bremsstrahlung deduced for Po-210 were 10(11)simil ar to 10(12)/keV/sr/decay for 100 less than or equal to E(gamma)less than o r equal to 600 keV. It was found that the bremsstrahlung yields are much sm aller than those predicted by a Coulomb acceleration model. This suggests t hat alpha-particles also emit photons inside the barrier. The bremsstrahlun g spectrum was compared with a quasi-classical calculation in which the bre msstrahlung emission in tunneling motion of alpha-particles is taken into a ccount. It is shown that the data can be interpreted as a consequence of de structive interference of radiative amplitudes outside the: Coulomb barrier with those in tunneling.