Deuteron-deuteron nuclear reactions at extremely low energies

The theoretical analysis of the 2H(d,p)3H reaction taking place in both metallic as well as gaseous targets at deuteron energies of several keV presented here indicates a strong contribution of the single-particle 0+ threshold resonance. Additional arguments based on the weak coupling between the 2 + 2 and 3 + 1 clustering states of the compound nucleus 4He support this resonance and suggest its large partial width for the internal electron-positron pair formation that overestimates the proton width. A detailed study of the interplay between the resonance transition and the electron screening effect enables estimation of the nuclear reaction rate of the deuteron-deuteron fusion reactions at room temperature.