Is it possible to observe an isoscalar E1-multipole in reactions?

Abstract Radiative capture of deuterons by α-particles (αd→ 6 Liγ) and the inverse reactions are considered in the framework of the potential cluster model. Special attention is paid to corrections to the E1 multipole in the long wave approximation which can compete with the dominant E2 multipole. It is shown that these corrections could already be detected in the experimental data on the angular distributions of photons. The asymmetry of the deuteron angular distributions in polarized γ-quanta disintegration could be another quantity where the E1 transition could be exhibited. Among many corrections, the one which is due to the mass difference between the α-particle and two times the deuteron mass is the most important.