Accurate measurements of Gamow-Teller strength distributions are important for understanding nuclear structure, neutrino physics, and nucleosynthesis. This paper discusses the measurement of the 116,122 Sn3 ( He, t)116,122 Sb charge-exchange reactions at 140 MeV/u, from which the Gamow-Teller strength distributions were extracted for 116 Sb and 122 Sb between 0 and 28 MeV excitation energy. The experiment was performed using the high-energy resolution Grand Raiden spectrometer at the Research Center for Nuclear Physics in Osaka, Japan. The results are discussed by comparing them to other experiments and theoretical calculations, and provide important benchmarks for theoretical studies that can have implications on nucleosynthesis processes. Three MWDC layers successfully detected a particle and reconstructed triton tracks through the focal plane when only three MWDC layers produced a signal. The detection efficiency per MWDC layer was found to be about 95% in the 0◦ mode and about 89% in the 2.5◦ mode. The differential cross sections were determined per excitation-energy bin of 200 keV by using the total number of measured counts in the bin as P(θ). The B(GT) values for the low-lying states were extracted from the differential cross sections of observed discrete states. The B(F) values of the IAS were determined and found to be in good agreement with the expected B(F) = |N − Z |. The data-analysis procedure allowed for the extraction of B(GT) values from the differential cross sections of observed discrete states, as well as from the differential cross sections per excitation-energy bin of 200 keV. Pham et al. studied the Gamow–Teller strength distributions in the Sn(3 He, t)Sb reaction for several isotopes at a beam energy of 67 MeV/u. They used a sum of Gaussians to fit the Gamow–Teller (GT) resonances, the IAS and the isovector (spin) giant dipole resonance (IV(S)GDR). A quasi-free background model was also added. We compared the data presented in this paper to theirs for the 116 Sn and 122 Sn targets. We used a two-point MDA to determine the Gamow–Teller unit cross section at 67 MeV/u and extrapolated this result to the isotopes of interest. We found a Gamow–Teller unit cross section of 2.53 mb/sr for the 116 Sn target and 2.40 mb/sr for the 122 Sn target. A comparison between the B(GT) values obtained from the Pham et al. data and the B(GT) values obtained from the present experiment showed a significant deviation for the IAS and GT1 of the 122 Sn target. This could be explained by systematic uncertainties in the fitting procedure of Fig. 17. The cross section of the 118Sn target at 67 MeV/u was established to be 87% Gamow-Teller contribution, but this number contains a large uncertainty. The 116Sn and 122Sn targets have no a priori reason to assume the same number. Pham et al. claimed that GT1 contains 65% of the Ikeda sum rule, but the second columns of Tables 4 and 5 claim that GT1 of the 116Sn target only contains 14%, and 19% for the 122Sn target. This is explained by the ratio of Fermi and Gamow-Teller unit cross sections being different for (p,n) and (3He,t) reactions. The comparison to the 150Nd(3He,t)150Pm reaction studied by Guess et al. at 140 MeV/u showed that all three isotopes overlap near 17 MeV, but the 116Sn target starts to deviate again at higher excitation energies. The comparison to QRPA+QPVC calculations showed reasonable agreement, but the 3-5 MeV region was not reproduced. To accurately determine the quasi-free background, it An experiment was proposed to measure the size of the quasi-free background contribution to the 116 Sn(3 He, t)116 Sb reaction at 140 MeV/u. The experiment would confirm that the quasi-free contribution is small and allow for a better agreement between the Ikeda sum rule percentages of the two Sn-targets. The experiment is challenging due to the high count rates and other nuclear reactions at forward angles. A QRPA+QPVC calculation with the inclusion of contribution from excitations of other multipolarities up to 28 MeV/u is needed to better understand the general quenching phenomenon.
