Heavy-ion charge-exchange reactions and the measurement of Gamow-Teller strength

Abstract

The applicability of intermediate-energy heavy-ion charge-exchange reactions for measuring GamowTeller strength in nuclei is studied. A strong absorption model for such reactions is developed. Within the framework of this model, we define a sensitivity function which determines the important region of the target transition density in momentum space. It is found that the L =0 cross section provides a relatively mode1-independent measure of Gamow-Teller strength. An understanding of the large L =2 cross sections observed in heavy-ion-induced reactions is achieved. Specific application is made to the (' C, ' B) reaction at E/A =70 MeV.PACS number(s): 25.70.Hi

Nucleon Charge-Exchange Reactions at Intermediate Energy

“…This is because GT transition densities all peak at q = 0, but for momentum transfers greater than 1fm -1 the densities show a strong variation from state to state which should result in state-dependent variations in the ratio of cross section to GT strength, along with an admixture of cross section with L = 2. However, quantitative calculations using a strong absorption model [88] have shown that the L = 0 part of the cross section is almost completely insensitive to momentum transfers greater than 0.8 fm -1 , thus accounting for the observed proportionality.…”

“…Following the publication ofthe results of Bainum et al, for the 90 Zr(p,n) 90 Nb reaction at 120 MeV, Mathews et al [107], showed that the observed distribution of GT strength was well accounted for by a shell model calculation with a model space of the (2p1g) shells. Another calculation by Muto et al [108], assumed a closed core of 88 Sr with single particle excitations into the (3s, 2d, 1g) shells. Using single particle energies and two-body matrix elements from fits to level schemes in that mass region, a satisfactory fit to the GT strength distribution was obtained.…”

High Energy Approaches to Low Energy Phenomena in Astrophysics

“…The first experiments involving radioactive nuclei were those of Motobayashi, et al [15] at RIKEN, on the breakup of 14…”

Do hadronic charge exchange reactions measure electroweakL=1strength?

“…We show that, at the same level of accuracy as for the GT case, for strong transitions one can expect an approximate proportionality between the observed cross sections of charge exchange reactions populating spin-dipole states and the corresponding nuclear transition probabilities. We follow the general approach that was successfully applied to GT excitations by Osterfeld et al [18], extended to describe L = 1 transitions and the effects of the real part of the optical potential.…”