W. Dodge

Trinucleon Threshold Electrodisintegration

Inclusive inelastic electron scattering cross sections for 3H and 3He were measured for excitation energies below 18 MeV. For six values of the three-momentum transfer q in the range 0.88 < q < 2.87 fm−1, longitudinal and transverse response functions were determined. The experimental data are in good agreement with two recent calculations. One uses variational ground-state wave functions and the orthogonal correlated states method to describe the two- and three-body breakup channels. The other uses bound and continuum Faddeev wave functions for a simple central potential. The inclusion of final-state interactions (FSI) in the Faddeev continuum is found to be very important; inclusion of FSI changes the response functions in the threshold kinematics by a large amount, yielding excellent agreement with the data.

Isovector Giant Quadrupole Resonance in (p↘,γ)

The 30Si(p↘,γ)31P reaction has been studied in the energy range Ep=20–36 MeV. A transition matrix element analysis of σ(θ) and σ(θ)Ay(θ ) at Ep=25.5 MeV reveals substantial E2 strength (σE2/σtot∼26%) in the (p,γ1) channel, in excess of a direct E2 capture estimate (∼7%). The energy dependence of Ay(90°) for γ1 shows a resonance structure which can be reproduced by a direct‐semidirect calculation including an E2 resonance (EIVGQR=38.6 MeV, ΓIVGQR=5.0 MeV, SIVGQR=50%) at the expected peak of the isovector giant quadrupole resonance built on the first excited state of 31P. Angular distributions of σ(θ) and σ(θ)Ay(θ) have also been obtained from the 89Y(p↘,γ)90Zr reaction at Ep=22.5 MeV. A preliminary analysis reveals large E2 contributions (∼28%) for the γ0 transition, as well as possible E3 strength.