The Spin-Flip Scattering of High Energy Protons by Light Nuclei

概要

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The spin-flip inelastic scattering of high energy protons is investigated for the 15.1 Mev excitation of C^<12> and the 9.2 Mev excitation of N^<14>. The electromagnetic interaction is found to be far too weak to account for the observed cross sections. The spin-flip cross sections due to the (σ_1・σ_2) (τ_1・τ_2) part of the nuclear interaction are calculated by means of the impulse approximation. In the case of C^<12> the cross section can be calculated without referring to any special nuclear model from the ft-value of the β-decay of B^<12> or N^<12> to the ground state of C^<12>. The result agrees very well with the experimental cross section showing the validity of the assumptions involved in the calculation. It is also shown that the spin-flip scattering is the only process which shows the angular distribution with maximum at 0° leaving the residual nucleus in a discrete low-lying excited state. The nuclear matrix element of the transition estimated conversely from the observed cross section may be used as a datum for the relevant nuclear states. In particular the separate contributions of the spin and the orbital angular momenta to the M1 γ-transition between the relevant states can be estimated and are found to be of the ratio 1 to 0.3 both for C^<12> and N^<14>. Discussions are given on the approximations used in the calculations as well as on the nuclear states relevant to the excitations.
理論物理学刊行会の論文
1962-02-25