S. E. Vigdor

Momentum transfer in 30–200 MeV 4H induced reaction with 59Co

Abstract Thick-target recoil ranges of radioactive nuclei produced in 30–200 MeV alpha-particle bombardment of 59Co have been used to deduce the longitudinal momentum transfer per projectile nucleon (p‖/A) as a function of residue mass and bombarding energy. The average value of p‖/A increases monotonically with bombarding energy and reaches a maximum value of ≈ 160 MeV/c at ≈ 23 MeV/u, and decreases thereafter. The maximum value of p‖/A is equal to the incident momentum up to ≈ 23 MeV/u and saturates at a value of ≈ 220 MeV/c beyond this energy.

On the anisotropy of multi-chance, high-spin fission

Inclusion of the fission-fragment anisotropy in statistical-model analyses is shown to provide significant constraints on the spin and chance distributions for high-spin fission. Selective anisotropy measurements which should enhance sensitivity to shell or pairing corrections in the late stages of compound-nucleus decay are suggested.

Measurement of the absolute differential cross section for np elastic scattering at 194 MeV

A tagged medium-energy neutron beam was used in a precise measurement of the absolute differential cross section for np backscattering. The results resolve significant discrepancies within the np database concerning the angular dependence in this regime. The experiment has determined the absolute normalization with {+-}1.5% uncertainty, suitable to verify constraints of supposedly comparable precision that arise from the rest of the database in partial wave analyses. The analysis procedures, especially those associated with the evaluation of systematic errors in the experiment, are described in detail so that systematic uncertainties may be included in a reasonable way in subsequent partial wave analysis fits incorporating the present results.