Peter Hillman

High energy (p,2p) reactions and proton binding energies

The energy carried away by each of the two coincident protons from (p, 2p) reactions in elements bombarded by 185 MeV protons has been measured by range analysis. To the extent that the collision is quasi-elastic, the difference between the sum of these energies and the incident energy, corrected for the recoil energy of the residual nucleus, gives the binding energy of the struck proton in the nucleus. Sharp groups which can be associated with the nuclear shell structure have been observed in the light elements. The results determine directly the spin-orbit splitting in the 1p-shell and the binding energy of the 1s-shell for the lightest nuclei. Only the spectrum of Be9 might give some indication of an α-particle structure.

Quasi-elastic scattering and nuclear structure

Abstract Energy and angular correlation measurements on the two protons emerging from high energy (p, 2p) processes may give direct information on the structure of the ground state of the bombarded nucleus and of certain excited states of the residual one. Expectations are derived on the basis of the assumptions of the approximative validity of the shell model and the Serber-Chew hypothesis of the reaction mechanism. The influence of multiple collisions in the nucleus is considered.

Inner shell structure of nuclei

States in which the inner shells are intact are comparable with atomic states leading to optical transitions. The nuclear states corresponding to x-ray states in atoms have holes in inner shells. The purpose of this note is to report preliminary results of a method of investigating such states. (A. C.)

Inelastic scattering of high energy protons by helium: An excited level?

Abstract No clear evidence for the existence of an excited level has been found in an investigation of the energy spectra and polarizations of 185 MeV protons inelastically scattered by He4 in the angular region 6.5°–43.5°lab. An upper limit of 0.02 mb · sr−1c.m. has been obtained for the excitation of an excited level in the region 4–17 MeV excitation energy in 33.5°lab scattering of these protons. A peak in the energy spectra is seen at all angles at 22.5±0.4 MeV excitation energy, which is quite well fitted with a simple model of quasi-free nucleon-nucleon scattering with a final state interaction for which the parameter values required, however, seem anomalous.