C. Olmer

High-spin 1p-1h configurations in sn-116 and their fragmentation as seen in the reactions sn-116(-]p,p'), sn-116(e,e'), in-115(3he,d) and in-115(alpha, t)

Stretched spin configurations in 116Sn have been studied via the reactions 116Sn(p, p′), 116Sn(e, e′), 115In(3He, d) and 115In(α, t). The high-spin negative parity two-neutron quasiparticle states within the N = 51 − 82 major shell appear to be little fragmented. The most prominent examples are the Iπ = 9- state at Ex = 3.522 MeV and two 7− states at 2.909 and 3.120 MeV. It is found that in contrast the proton configurations (g−192, h112) and (g−192 g72) are strongly fragmented. Large-basis BCS shell model calculation, using a SkE-force have been made and DWBA analyses of the (e, e′) data and of the (p, p′) data are presented.

An in-beam polarimeter for intermediate energy protons using p + d elastic scattering

The importance of high quality spin-observable data in intermediate energy nuclear physics requires that techniques be developed for obtaining accurate and reliable measurements of incident beam polarizations in a nondestructive manner. For this purpose, we have constructed, installed, and calibrated two transmission-type polarimeters at IUCF, in which p+d elastic scattering is used to determine the two transverse polarization components of a high energy proton beam. In this report, we discuss some of our experimental design considerations, and provide technical details on the actual implementation schemes chosen. Representative spectra are shown, and typical performance capabilities are described. We have also completed a calibration of the effective analyzing power of the polarimeter (Apol) as a function of the incident (beam) proton energy, and find Apol ≈ 0.51 over the entire proton energy range studied in this work ( ∼ 150–200 MeV) when θdlab = 42.6°.

Analyzing powers for the proton excitation of high-spin states in 28Si: A new look at the effective interaction☆

Abstract Analyzing powers have been measured for the 5−, T = 0, 6−, T = 0 and 6−, T = 1 high-spin states in 28Si using the inelastic scattering of polarized protons at 135 MeV. These data contain new information on the spin-independent central and the tensor components of the effective nucleon-nucleon interaction at high momentum transfer. The new measurements are in reasonable agreement with distorted-wave impulse approximation calculations.

Implications of far-side dominance for the disagreement between distorted wave theory and well-matched intermediate energy (d, p) reactions

Abstract Distorted wave calculations of large l n -transfer (d, p) reactions near 90 MeV indicate that far-side dominance reduces the number of effective amplitudes at large angles to two or three, making many spin observables redundant. Comparisons of A y with A yy data for 116 Sn(d, p) 117 Sn, and A yy with p y data for 66 Zn(d, p) 67 Zn, do not confirm this expectation.

Low-lying excitations in sup 176 Yb and sup 180 Hf from ( rvec p , p prime ) scattering at E sub p =98. 4 MeV

The low-lying excited states of two rotational nuclei, {sup 176}Yb and {sup 180}Hf, have been investigated up to an excitation energy of 3.5 MeV by means of high-resolution inelastic scattering of 98.4-MeV polarized protons. The spins and excitation strengths of the observed levels have been deduced by comparing the measured cross sections and asymmetries with coupled-channel calculations. The deduced quadrupole, hexadecapole, and octupole strengths have been compared with the predictions of the interacting boson model in the {ital sdg}- and {ital sdf}-boson schemes.

Inelastic scattering of low‐ and intermediate‐energy polarized protons from various light nuclei

Analyzing powers and differential cross sections for inelastic proton scattering from 28Si, 20Ne, and 16O targets at an incident proton energy of Tp=135 MeV are presented. These observables have also been modeled with a microscopic approach using the Paris‐Hamburg effective NN potential. (AIP)

Fragmentation of ‘‘stretched’’ 6− strength in 28Si(p↘,p↘′)28Si

Using a 198.3 MeV polarized proton beam, measurements have been made of the dσ/dΩ, A and DNN′ for the 28Si(p↘,p↘′)28Si reaction to locate the 6− strength for comparison with large basis shell model calculations. Based on both dσ/dΩ and A data, six states above 15 MeV were determined to carry 6− strength. The measurements of & were used as a meter of isospin mixing. The shell model calculations do not match the experimental results.

Studies of Spin Excitations Using Polarized Protons

The energy dependence of 28Si(p,p’) has beea studied using polarized proton beams at energies between 80 and 180 MeV. Differential cross sections and analyzing powers have been determined for elastic scattering and for inelastic excitation of the following states: 6-, T=1 (14.35 MeV), 6-, T=0 (11.58 MeV), and 5-, T=0 (9.70 MeV). The results are compared with distorted-wave impulse approximation calculations using the Love-Franey t-matrix and an earlier effective interaction. Rather good agreement is found with the DWIA description of these transitions. Some refinements to the standard model are discussed.