Morikazu Nomoto

Reactions on 209Bi induced by intermediate energy protons and the effect of direct reactions

Abstract Excitation functions and ranges of recoil nuclei in the 209 Bi(p, 3n) 207 Po, 209 Bi(p, 4n) 206 Po and 209 Bi(p, p3n) 206 Bi reactions have been measured for incident energies from 18 MeV up to 52 MeV. It has been found that the recoil ranges in (p, p3n) reactions are rather shorter than those in (p, 4n), and that beyond E p = 40 MeV the high energy tail of the excitation function for (p, p3n) is roughly flat, in contrast to the decreasing tail for (p, 4n). A theoretical analysis of the excitation functions and of the nuclear recoil ranges has been made. It has been found that in (p, p3n) reactions the direct process plays a very important part in the reaction mechanism. It is also found that the reaction mechanisms of (p, 3n) and (p, 4n) reactions should be interpreted by means of an admixture of the equilibrium compound process and the pre-equilibrium decay process at bombarding energies up to 40 MeV and 50 MeV, respectively, and that the direct process seems to appear at bombarding energies higher than these respective energies.

Singlet deuteron pick-up reactions

Abstract The singlet deuteron pick-up reaction in the reaction A(p, p′n)B is studied theoretically. The energy spectra and the angular distributions of the proton from this reaction by the singlet deuteron pick-up process as well as by the direct three-body break-up process are calculated with the plane wave Born approximation and a finite range p-n interaction potential. The formulae obtained are applied to the reactions 13C(p, p′n)12C with the incident proton energy Ep = 15 MeV (in the lab system) and 9Be(p, p′n)8Be with Ep = 5 MeV, and the contributions of the singlet deuteron pick-up process to the emitted proton spectra and the angular distributions are discussed. These contributions are compared to those of the other processes.

Deuteron Distortion Effects in the (d, d) Scattering and (d, p) Reaction

We investigate the distortion effects of the deuteron during the 28 Si(d, d) 28 Si scattering and 28 Si(d, p) 29 Si reaction. The calculated results show that the deuteron shrinks as often pointed out and the binding energy decrease rapidly in the inner part of the target nucleus. The distortion effects of the incident deuteron appear clearly in the elastic scattering and reaction.

Pairing Energy for Deformed Nuclei

The pairing energy for strongly deformed nuclei is estimated by dividing the energy into two parts, one of which is the interaction energy between the nucieons forming the last pair, while the other part arises from the deformation of the nucleus. Assuming an attractive inner-nucleon force with a short range, the interaction energy in the last pair is first estimated on the Nilsson model, and is then estimated in the case where the deformation is extremely strong. The deformation energy is estimated on the unified model. The calculation is carried out for the last neutron pairs of the five nuclei Gd/sup 158/, Dy/sup 164/, Yb/ sup 174/, Hf/sup 178/, and Hf/sup 180/ in the rare earth region. The results obtained by using the Nilsson model as well as the unified model are in fairly good agreement with the experimental data. (auth)