K I Pearce

Elastic scattering of 33 MeV tritons and isospin dependence of mass-3 optical potential

Abstract Differential cross section data are presented for the elastic scattering of 33 MeV tritons from a range of nuclei from 12 C to 232 Th. These data have been analysed using a phenomenological optical model. Parameters are presented for three families of the real potential. A comparison of the triton optical model potential with those from a re-analysis of 3 He scattering from fp shell nuclei has allowed the isospin dependence of the optical model potential for mass-3 projectiles to be obtained in this mass region.

36 MeV triton inelastic scattering and one-nucleon transfer reactions

Abstract Differential cross sections have been obtained for inelastic scattering and one nucleon transfers on targets of 28,30 Si and 26 Mg using a 36 MeV beam of tritons. CCBA and DWBA fits have been applied to these data and the deformation parameters and spectroscopic factors obtained compared to previous measurements and shell model predictions. Comparisons are made of the fits obtained with zero-range, local energy approximation and exact finite range calculations. High energy tritons are shown to be a precise and valuable spectroscopic tool.

Consistent description of the (t, 3He) reaction for A = 12−89

Abstract New differential cross section data for seven target nuclei were analysed using a microscopic model. Particular care was taken to ensure that the absolute magnitude of the cross sections was correctly measured. The predicted direct or one-step (t, 3 He) reaction did not account for the magnitude of the data except for forward angles and A ⩾40. The calculations were estended to include the contributions from two-step or sequential single-nucleon transfers. Calculations were made using the second-order DWBA and zero-range or full finite-range forms. In the latter the non-orthogonality between the basis states in the two-step transfers was included. The transfer amplitudes were deduced from comparisons of predicted angular distributions with data obtained from the (t, α) and (t, d) reactions, and from amplitudes determined by repeating previously reported shell-model calculations. The full finite-range DWBA calculations which included non-orthogonality terms, accounted for both the shape and magnitude of the data within a factor of 3 in the worst case. The (t, α) reaction angular distributions are, however, poorly predicted.

Elastic scattering of 36 MeV tritons

36 MeV triton elastic scattering data have been obtained for targets of 30Si, 28Si, 26Mg, 16O and 12C. These data are analysed in terms of a conventional phenomenological optical model and double-folding optical model.

New measurements of the mass and energy levels of 22F

New measurements are presented of the ground-state mass of 22F derived from the 22Ne(t,3He)22F reaction at Et=33.4 MeV. Twenty two levels have been identified in 22F and the excitation energies determined. Some J values for the states have been assigned from DWBA calculations, and compared with shell model predictions.

The importance of the tensor interaction in the (7Li, 7Be) reaction

Data for the 28Si(7Li,7Be)28Al reaction at 72 MeV and for the 26Mg(7Li,7Be)26Na reaction at 88 MeV are presented together with one-step DWBA calculations using microscopic form factors. The tensor interaction is shown to be important to explain the structureless nature of the angular distributions.

High-lying levels in 24NE

Levels in 24Ne between 5.7 and 12 MeV of excitation have been measured from the 22Ne(t,p) 24Ne reaction at 33.4 MeV. Some limits to the J values for the states have been assigned from DWBA calculations. A new 0+ state has been found near 5.7 MeV of excitation. The spectrum of 24Ne has been compared with shell model predictions.

Triton- and helion-induced cluster pick-up reactions on 12,13C

Differential cross sections have been measured for the reactions (t,6He), (t,6Li), (t,7Li), (t,9Be) on 12,13C; (t,8Li) on 13C; for (3He, 6Li) on 12,13C and (3He, 7Be) on 12C over the range 10 degrees -100 degrees CM. For the (3He, 7Be) and (3He, 6Li) reactions on 12C, analysing powers were measured over the range 20 degrees -75 degrees CM. Finite-range DWBA analyses have examined the effects of different optical potentials, including spin-orbit potentials, and bound-state potential geometries. Microscopic descriptions of the alpha -projectile cluster wavefunction and a number of potential descriptions have been used to generate form factors for the alpha -pick-up reactions. Spectroscopic factors have been extracted for all the reactions and compared with shell-model calculations.

The location of stretched states in 26Na and 30Al

The differential cross sections for the (t,3He) reaction to states in 26Na and 30Al have been compared with DWBA calculations. Candidates for the 5+ states have been found at 3.91 MeV in 30Al and at 2.29 MeV and 5.08 MeV in 26Na. A possible 5+ state has been found at 2.89 MeV in 30Al. The energy levels predicted by the USD shell model are compared with the experimental spectra.

A study of 52V with the 51V(t, d) reaction

Abstract A 33 MeV tritium beam was used to induce the 51 V(t, d) 52 V reaction. Angular distributions of the differential cross sections were measured for 51 deuteron groups up to 6.5 MeV excitation energy in 52 V. A further 14 states were identified below 10.7 MeV excitation. DWBA analyses of the results were employed to deduce angular momenta of the transferred neutron and the corresponding spectroscopic strengths. Shell-model calculations performed in the 0p-0h space give good descriptions of the experimental data.