First measurement of the d(p,\u3b3)3He cross section down to the solar Gamow peak

Using the 50 kV LUNA accelerator facility at the Gran Sasso underground laboratory we measured, with an accuracy of the order of 10%, the d(p,gamma)He-3 cross section from 22 down to keV c.m. energy, well below the solar Gamow peak. The experimental set-up was based on a large solid angle, segmented BGO detector and a renewed windowless gas target. The astrophysical S(E) factor within the Gamow peak is in fair agreement with the value of one of the existing extrapolations of data at higher energies