THEORETICAL-STUDY OF THE RADIATIVE-CAPTURE REACTIONS H-2(N,GAMMA)H-3 AND H-2(P,GAMMA)HE-3 AT LOW ENERGIES

Correlated hyperspherical harmonics wave functions with Delta-isobar a dmixtures obtained from realistic interactions are used to study the t hermal neutron radiative capture on deuterium, and the H-2((p) over ri ght arrow,gamma)He-3 and P((d) over right arrow,gamma)He-3 reactions i n the center of mass energy range 0-100 keV. The nuclear electromagnet ic current includes one- and two-body components. Results for the H-2( (n) over right arrow,gamma)(3) cross section and photon polarization p arameter, as well as for the energy dependence of the astrophysical fa ctor and angular distributions of the differential cross section, vect or and tensor analyzing powers, and photon linear polarization coeffic ient of the 2H((p) over right arrow,gamma)He-3 and p((d) over right ar row,gamma)He-3 reactions are reported. Large effects due to two-body c urrents, in particular the long-range ones associated with the tensor component of the nucleon-nucleon interaction, are observed in the phot on polarization parameter and vector analyzing power. Good quantitativ e agreement between theory and experiment is found for all observables ; with the exception of the vector analyzing power for which the calcu lated values underestimate the data by about 30%.