Gamow–Teller strength extraction from (3He, t) reactions

Details of Gamow–Teller (GT) and Fermi (F) strength extraction from charge-exchange reactions at intermediate energies, as well as the concept of using the phenomenological effective interaction for the description of the reactions are reviewed. The focus lies on high-resolution (3He, t) data, yet new data on (d, 2He) charge-exchange reactions are presented as well to indicate the connection and the similarity of both probes to the elementary (p,n)(p,n), resp. (n,p)(n,p) reactions. We show that for the extraction of B(GT)B(GT) and B(F)B(F) strength a proper extrapolation of the charge-exchange cross section to the zero momentum transfer point, q=0q=0, gets to be increasingly important for medium to high-mass target nuclei and at moderate excitation energies of a few MeV. Numerous (3He, t  ) and (p,n)(p,n) spectra are being compared, and, once adjusted for the different momentum transfers, they reveal a remarkable similarity up to the highest measured excitation energies of ≈25 MeV≈25 MeV. Further, we remark that the precision, with which GT and F transition strengths can be extracted, is limited by the relatively poor knowledge of the absorption processes, and a more thorough theoretical understanding of the nuclear structure leading to absorption in charge-exchange reactions, especially in the restricted kinematic region of low-momentum transfers, is warranted. Finally, B(GT)B(GT) values for the 136Xe(3He, t) are being re-evaluated in the light of the present discussion.