Search for Gamow-Teller strength in the continuum via theHe3(n,p)

Abstract

Cross sections for the He(n, p) reaction were measured at angles of 2.7 ', 7.5', 14.4', 28.2', and 34. 9' (c.m. ) at an incident beam energy of 288 MeV. Outgoing protons were observed to energies corresponding to a Q value of -40 MeV. The reduced cross section for the Gamow-Teller component of the ground-state isobaric-analog transition was determined to be & =o(q =0)/BGT =6.9+0.2 mb jsr. This value is significantly smaller than that observed for nuclei in the mass range 6~A~1 3. A multipole analysis of the data indicates that the cross section of the continuum up to a g value of -20 MeV involves mainly hL =1 spin dipole transitions. The analysis determines an upper limit of 0.06 units of Gamow-Teller strength in transitions to excited states between 7 and 16 MeV, but is consistent with no Gamow-Teller strength in this region. Distorted wave impulse approximation calculations using transition amplitudes from a large-scale shell model calculation provide a good fit to the measured groundstate cross section, but fail to account for the magnitude of the measured cross sections to the continuum below 30 MeV excitation.PACS number(s): 24.50.+ g, 25.40.Kv, 27.10.+h

Gamow-Teller unit cross sections for (t,He3) and (Perdikakis1, Zegers2, Austin3 et al. 2011Phys. Rev. C403410View full textAdd to dashboardCite

“…Single-particle states in 3 He and 3 H were generated in a harmonic oscillator potential with oscillator parameter b = 1.4 fm, following Ref. [50]. The effective interaction used in the calculations was the Love-Franey interaction [40,41] at 140 MeV.…”