Angular analysis of bremsstrahlung in alpha decay

A new quantum electrodynamical method of calculations of bremsstrahlung spectra in the $\alpha$-decay of heavy nuclei taking into account the angle between the directions of $\alpha$-particle motion (or its tunneling) and photon emission is presented. The angular bremsstrahlung spectra for $^{210}{Po}$ have been obtained for the first time. According to calculations, the bremsstrahlung in the $\alpha$-decay of this nucleus depends extremely weakly on the angle. Taking into account nuclear forces, such dependence is not changed visibly. An analytical formula of the angular dependence of the bremsstrahlung spectra is proposed and gives its harmonic behavior. The extremal values of the angle, at which the bremsstrahlung has maximal and minimal values, has been found.Comment: 15 pages, 1 file of figure in EPS format, LaTeX v.2e with EPJ style. In the new variant of the paper: 1) more attention is given to a convergence problem of computer calculations of the bremsstrahlung spectra; 2) a new section with inclusion of Woods-Saxon component in construction of the total realistic $\alpha$-nucleus potential into our model (with our first brermsstrahlung spectra for $^{210}{Po}$ at such potential) is included into the paper; 3) possible ways of further improvement of the quantum-mechanical models are pointed ou