H.H. Forster

Elastic scattering of 31 MeV protons from H2, He3, N14 and O16

Abstract The differential elastic scattering cross sections for 31.0 MeV protons have been determined for gaseous, isotopic targets of H2, He3, N14 and O16 at c.m. angles ranging from ≈ 6° to ≈ 160°. An optical model analysis of the experimental data was performed on He3, N14 and O16 using a model which included both volume and surface absorption. Good fits were obtained over most of the experimental range. Optical model parameters corresponding to best fits are presented and compared with those obtained in this energy range for other light nuclei.

New short-lived isomeric levels in Tl201m and Tb153m

Abstract Isomeric levels in thallium and terbium isotopes in the ms range were studied by examining the gamma de-excitation spectra following the bombardment of Hg and Gd isotopes with 30.5 MeV protons. A new isomeric level was identified in Tl 201m both from the Hg 201 (p, n)Tl 201m and Hg 204 (p, 4n)Tl 201m reaction, with a half lile τ = 1.8±0.1 ms. The gamma spectrum of the isomer showed three prominent lines with energies of 0.225±0.010 MeV, 0.325±0.010 MeV and 0.585±0.010 MeV. A level scheme with a spin of 9 − 2 for the isomeric level is suggested for Tl 201m . A new isomeric activity was found in Tb 153m from the Gd 154 (p, 2n)Tb 153m and Gd 155 (p, 3n) Tb 153m reactions with a half life τ = 0.173±0.010 ms and E γ = 0.078±0.005 MeV.

Interactions of 31 MeV protons with He4

Abstract Angular distributions for the He4(p, p)He4 and the He4(p, d)He3 reactions were determined for a proton energy of 31.0 MeV at centre-of-mass angles ranging from ∽ 6° to ∽ 160° for elastic proton scattering and from ∽ 15° to ∽ 100° for the deuteron pickup reaction. The differential elastic scattering cross section was fitted by an optical model analysis which included both surface and volume absorption. The deuteron angular distributions were fitted by calculations based on the direct interaction theory of Butler and the distorted wave Born approximation with diffuse-well optical potentials as proposed by Smith and Ivash.

Elastic and inelastic scattering of 30.8 MeV protons from Ni60 and Pb208

Abstract The angular distributions of 30.8 MeV protons scattered elastically from Ni60 and Pb208 targets were obtained at angles ranging from ≈ 6° to ≈ 155° in the centre-of-mass system and the data fitted by an optical model calculation which included both volume and surface absorption. Angular distributions of protons scattered inelastically from the 1.33 MeV (2+) level in Ni60 and from the 2.62 MeV (3−) level in Pb208 were measured and compared with the results of the inelastic diffraction scattering model of Blair.

Excited levels in 3He

Abstract The inelastic proton spectrum from the 3He + p reaction was investigated in a search for excited states in 3He. Possible evidence for the existence of virtual levels is discussed.

Gamma-gamma directional correlation in Ba136 and Mo94

The gamma-gamma directional correlation was measured for the 1.065 to 0.830 Mev gamma cascade in Ba/sup 136/ and for the 0.700 to 0.874 Mev cascade in Mo/sup 94/. The experimental correlation is compatible with either a 4/sup +/ (Q)2/sup +/ (Q)O/sup +/ or a 2/sup +/(D + Q)2/sup +/(Q)O/sup +/ level sequence for the lowest states in either nucleus. A 2/sup +/ assignment for the second excited state leads to a predominantly Ml transition between the second and first excited state, e.g., the quadrupolei content in Ba/sup 136/ is 2.7 plus or minus 0.6%, that of Mo/sup 94/ is 4. 4 plus or minus 0.4%. (auth)

The circular polarization of the gamma rays following the β decay of Fe-59

Abstract The circular polarization of the gamma rays emitted in the beta decay of Fe 59 has been measured using the method of forward scattering from a magnetized Armco iron cylinder. A method is described to separate the effects due to the two dominant decay modes. For the 461 keV β-1.099 MeV γ cascade asymmetry coefficient A = −0.46±0.08 was determined; for the 271 keV β-1.20 MeV γ transition the asymmetry coefficient was A = −0.04±0.11.

Quasi-elastic proton-deuteron collisions in Li6 at 30 MeV☆

The angular correlations between coincident protons and deuterons following the 30-Mev proton bombardment of /sup 6/Li were investigated. The /sup 6/Li(p,pd)/sup 4/He reaction gives strong support for the cluster structure alpha + d in /sup 6/Li. (C.E.S.)

Proton-proton final state interaction in the p + 3He reaction

Abstract The proton-proton final state interaction was studied using the 3 He + p → d + p + p reaction both in single counter, kinematically “incomplete” ( E p = 30.2 and 46.0 MeV) and angular correlation, kinematically “complete” ( E p = 46.5 MeV) experiments. In the single counter experiment the angular dependence of the final state interaction was determined between ϑ lab = 10° and ϑ lab = 50°. A Watson-Migdal calculation was used to fit the experimental deuteron spectra near the high-energy cutoff; the calculated distributions obtained for a choice of reasonable parameters were found to be wider at the peak than the experimental data indicated. The angular correlation experiments were performed at counter settings at which the contributions from p-p final state interaction were expected to be relatively large; these particular experiments indicated: (i) that p-p final state interaction contributes significantly to the three-body process and, (ii) that the proton pair is preferentially emitted with an internal energy of E 2p ≈ 0.4 MeV. A Watson-Migdal calculation applied to the angular correlation experiments gave good agreement with the experimental results. An explanation for the difference in fitting single counter or angular correlation experiments is given.

The 3He(p, 2p)pn reaction at 35 MeV

Abstract The differential cross sections for the reaction 3 He(p, 2p)pn were measured at 35 MeV for the angular sets 35°–35°; 40°–40°; 45°–45°; 42°–30°; 45°-35°; 70°-35°. The data were compared to four-body phase-space calculations. Several deviations from the phase-space predictions were observed but no conclusive evidence for excited states in 3 He was found.