Relationship between Gamow-Teller Transition Probabilities and (p, n) Cross Sections at Small Momentum Transfers

Abstract

Gamow-Teller transition probabilities are extracted for eight nuclei with masses between 3 = 13 and 39 from medium-energy (p, n) reactions via the distorted-wave impulse approximation, and compared with experimental P-decay and with free-nucleon transition probabilities. These comparisons indicate strongly that the renormalization of the Gamow-Teller operator needed for (p, n) reactions on finite nuclei is different from that needed for P decay.

Beta decay of the MT=-1 nucleus 58Zn studied by selective laser ionization

“…It was possible to describe the difference by means of an empirical (p, n) operator. This operator was first introduced to explain cases where (p, n) GT strength was enhanced relative to beta decay [30].…”

Nucleon Knockout by Intermediate Energy Electrons

“…Our calculations for at MeV agree well with the calculations of Watson et a/. (368) 18-7.20. These calculations were performed for a fixed electron energy of 500 MeV and the invariant mass of the recoil system was held constant, equivalent to a proton with kinetic energy MeV incident upon the ground state of Five sets of calculations are shown.…”

Nucleon Charge-Exchange Reactions at Intermediate Energy

“…The bump was not seen at 25 MeV, but was prominent at 45 MeV. For 90 Zr the excitation energy of the centroid of the bump was close to that expected for a particle-hole state with configuration (πg 7/2 ) (vg 9/2 ) -1 , while the angular distribution of the cross section for the bump was similar to that for transitions to known 1 + states at lower excitation arising from the (πg 9/2 ) (vg 9/2 ) -1 configuration. Finally, the magnitude of the cross section was comparable to that predicted by DWIA calculations for a transition to the (πg 7/2 ) (πg 9/2 ) -1 configuration.…”

“…However, in a study of the (p,n) reaction on targets of 48 Ca, 90 Zr, I20 Sn and 208 Pb at 25, 35 and 45 MeV at Michigan State University, Doering et al [28], observed a broad bump in the 0 o reaction cross section for excitation energies a few MeV above the known isobaric analogue resonance as shown in Fig. 2.2a.…”

“…Reprinted from [28] with permission. (b) Time of flight spectra for the 90 Zr (p,n) reaction, at 120 MeV and 0, 5, and 10 o laboratory angles. The peak marked 'e' is the Gamow-Teller giant resonance, and 'd' is the isobaric analog state.…”