H. Tyrén

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.

Inelastic scattering of 185 MeV protons on oxygen, calcium and carbon

Abstract The energy spectra at various angles for the inelastic scattering of protons near 180 MeV on oxygen, calcium and carbon have been measured with a magnetic analyser. Maxima corresponding to excited states of the target nuclei have been resolved and some differential and total cross sections are reported.

Studies of inelastic scattering of 185 MeV protons on carbon

Abstract Studies of the inelastic scattering of 185 MeV protons on carbon have been performed using a magnetic analyser. Differential cross sections of protons, exciting clearly resolved levels in C12, are given.

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.)

Some remarks concerning measurements on inelastic scattering of 155–185 MeV protons on carbon, oxygen and calcium

Abstract Semi-quantitative theoretical expectations for the differential cross sections of high energy inelastic proton scattering are summarized and compared with the experimental results for carbon, oxygen and calcium. The general agreement is satisfactory. High energy proton scattering at small angles seems a promising tool for the study of the giant gamma resonances at least in light nuclei. Some remarks concerning the measured asymmetries and polarizations of the inelastically scattered protons are made.

Inelastic scattering of 185 MeV protons on nuclei with masses from fluorine to potassium

Abstract Inelastic spectra of 185 MeV protons scattered at two different angles on nuclei from fluorine to potassium are reported.

Inelastic high energy nucleon scattering on light nuclei

Abstract The excitation of a nucleus bombarded by nucleons of a few hundreds of MeV is considered as the result of individual interactions of the incoming nucleon with the nucleons of the nucleus. A simple two-particle model, in which a bombarding particle excites a particle moving in a potential well, has been calculated in the first Born approximation. It is shown that the resulting angular distributions have a strong forward dip and vanish at large angles. To a certain extent this result still holds for the case of a nucleus consisting of Fermi- particles with common and isobaric spins. In first order only those states can be excited whose wave functions have, in the sense of the independent particle model, a component differing only in the state of one particle from the ground state wave function. In the case of neutron scattering the cross section has a forward dip if the space part of the wave function of the excited particle is orthogonal to the space part of its ground state wave function. If this is not so, for example if the excitation can occur by a pure spin exchange, there may be a forward maximum. In proton scattering the Coulomb interaction could result in a forward peaked angular distribution by didipole excitation as well as in the above mentioned case of monopole transition. In higher approximation two or more particles in the nucleus can be simultaneously excited. The resulting cross sections are expected to be smaller and more isotropic than in the case of a one-particle excitation. The angular distributions for two types of collective excitation have also been calculated, in the first Born approximation, namely for the lowest quadrupole surface vibration and for the dipole vibration of the nuclear charge. The qualitative features of the experimentally measured cross sections of the scattering of 185 MeV protons on C12 are shown to be in agreement with the theoretical expectations.

INELASTIC SCATTERING OF 185 Mev PROTONS ON ELEMENTS BETWEEN Ca AND Zn

The energy spectra for inelastic scattering of 185Mev protons on V, Cr, Mn, Fe, Co, Ni, Cu, and Zn are given at angles between 10 and 18 deg (W.D.M.)

The scattering of 181 MeV protons off helium

Abstract The energy spectra of 181 MeV protons scattered off helium have been recorded with a magnetic analyser. Gaseous helium was used as a target, and four angles were studied: 10°.2, 14°.2, 18°.2, and 23°.2.