W.R. Coker

Study of the 10Be(d, p)11Be reaction at 25 MeV

The distribution of the single-neutron strength up to an excitation energy Ex = 7.0 MeV in 11Be was investigated with the 10Be(d, p)11Be reaction at Ed = 25 MeV. The 12+, g.s., 12−, 0.320 MeV and 1.785 MeV states are found to be excited with significant strength. The angular distribution for the 1.785 MeV state is typified by an orbital angular momentum transfer ln = 2. This together with other available data indicate that its spin is Jπ = (52)+. The spectroscopic factors for these three states are compared to the shell-model calculations of Teeters and Kurath and of Cohen and Kurath.

Elastic scattering of 0.8-GeV protons from C12, Ni58, and Pb208

Differential cross sections for elastic scattering of 0.8-GeV protons from /sup 12/C, /sup 58/Ni, and /sup 208/Pb have been measured. Preliminary analysis of the data in terms of the Kerman-McManus-Thaler formalism with spin-dependent nucleon-nucleon amplitudes shows sensitivity to details of proton and neutron matter distributions.

Contribution of single-nucleon transfer reactions to 40Ar(τ, t)40K☆

Abstract An analysis of the 40 Ar (τ, t ) 40 K reactions populating the 0 + analog state at 4.38 MeV and the 0 + antianalog state at 1.65 MeV with incident 3 He energies of 35 and 18 MeV is made, including contributions from a pickup-stripping reaction mechanism as well as a conventional direct reaction mechanism. Agreement in magnitude and shape between calculated and experimental cross sections is best when both mechanisms are allowed to contribute.

Analysis of stripping to analog resonances using complex energy eigenstates

An analysis is presented of 30.2 MeV92Mo(τ, d)93TcA angular distributions for seven isobaric analog resonances in93TcA, using complex energy eigenstates to provide single-particle resonance state functions as form factors for the DWBA calculations. Details of the computation and use of complex energy eigenstates or Gamov functions are given, and results of the analysis are compared both with previous92Mo(d,p)93Mo studies and with previous analyses of the isobaric analog resonances. It is stressed that Gamov functions make possible a simple and elegant description of direct reactions populating either single particle or isobaric analog resonances.

Multistep contributions in 88Sr(h, t) 88Y

Abstract Using a coupled-reaction-channels (CRC) description of nuclear reactions, we have studied the reaction 88 Sr(h, t) 88 Y to 4 − , 5 − , and 2 + , 3 + doublet states. The data, taken at 23 MeV, show angular distributions with anomalous shapes, which cannot be explained by simple distorted-wave Born approximation calculations; our calculations, including (h, α) − (α, t) and (h, d) − (d, t) intermediate processes, but neglecting the direct (h, t) mechanism, give a good description of the shapes and relative magnitudes of the angular distributions. Effects of configuration mixing are also studied.

Total and partial widths of isobaric analog resonances

Abstract Total and partial widths and resonance mixing phases for d 5 2 analog resonances in 87 Rb, 89 Y, 91,93 Nb, 93,97 Tc are calculated in the framework of a nonorthogonal, optical-model basis in a shell-model theory of reactions. The proton optical potential used is identical to that with which the experimental resonance parameters were extracted, for 89 Y and 91 Nb where the most detailed and unambiguous experimental studies have been made.

Energy dependence of the (p, np̃) reaction☆

Abstract Excitation functions for the quasi-elastic (p, np) reaction are presented 91 Zr, 119 Sn, 208 Pb and 209 Bi from threshold to 45 MeV. Attempts to fit the data with conventional macroscopic DWBA calculations, using the Becchetti-Greenless (BG) optical model parameters, show that for all four nuclei considered an extremely unrealistic but consistent energy dependence is required for the strength of the complex symmetry potential.

Complex microscopic effective interaction for (p, n) reactions

Abstract A simple recipe for generating a complex effective interaction for distorted wave Born approximation calculations from a real, microscopic charge-exchange form factor is investigated. The recipe is tested against angular distribution data for 208 Pb(p, n) and 209 Bi(p, n) from 25 to 50 MeV incident proton energy. The form factor resulting from the recipe is also compared qualitatively to complex effective coupling potentials, resulting from a charge-independent Lane-model formalism and from coupled-channion-channels calculations for a suggested multistep (p, d)—(d, n) reaction mechanism.

The elastic scattering of α-particles from helium at 0.85 and 0.65 GeV

Abstract Elastic scattering of α-particles from helium has been measured at bombarding energies of 0.85 and 0.65 GeV over the range of four momentum transfer from 0.9 to 3.8 (GeV/ c ) 2 . The results are compared with the predictions of an α-α potential obtained by a folding procedure using a p- 4 He potential and 4 He charge distribution.

Exact finite-range DWBA treatment of heavy-ion-induced reactions to unbound residual states

Abstract We show that when one considers heavy-ion-induced direct nuclear reactions, the narrowly localized reaction surface makes a traditional approximation used in analysis of light-ion reactions to particle-unbound states a very poor one. Even for unbound states having single-particle widths 10 −5 of their resonance energies, quite different heavy-ion angular distributions are predicted using weakly-bound states versus more realistic complex-energy eigenstates (Gamow states).