Gamow-Teller β+ decays and strength functions of (n,p) transitions in spherical nuclei

The effect of the particle-particle interaction on the Gamow-Teller β+ decay and strength functions of (n, p) transitions is studied. The integrated log ft values for the GT decays of 152Yb, 152,150Er, 146,148Dy and 96Pd are calculated in the RPA with separable particle-hole and particle-particle interactions. A good description of log ft is obtained with the constants χ1011 = -23/A MeV and G101 = 7.5/A MeV at vertical strokegA/gVvertical stroke = 1 and G101 = 7.9/A MeV at vertical strokegA/gVvertical stroke-1.25. From the available experimental data on β+ decays of nuclei far from stability one cannot conclude that the weak axial-vector constant gA is strongly renormalised in nuclei. The particle-particle interaction is shown to influence strongly the total strength S+ of (n, p) transitions by diminishing it (1.5-3.0) times. For the reaction 54Fe(n, p)54Mn at forward angles the calculated value S+=4.2 is in agreement with the experimental one. (orig.)