H.F. Lutz

Neutron pick-up on the five stable isotopes of titanium via the (3He, 4He) reaction

Abstract A magnetically analysed beam of 3He particles accelerated by the Livermore variable energy cyclotron has been used to study neutron pick-up reactions on the five stable isotopes of titanium. The reaction leads to states with isospins T+ 1 2 and T- 1 2 (where 2T = N−Z is the isospin of the nucleus). The results of the experiment have been compared with the neutron pick-up studies carried out with the (p, d) reaction. The distribution of the ln = 3 strengths has been compared with the predictions of the (1 f 7 2 )n configuration calculation of McCullen, Bayman and Zamick.

Elastic and inelastic scattering of protons by 18O

Abstract Differential cross sections for elastic and inelastic scattering of protons by 18 O have been obtained. Excitation curves from 7.89 MeV to 16.28 MeV exhibit a large resonance at 10.5 MeV. Angular distributions were obtained at 11 values of the incident energy. The elastic angular distributions were fitted with the optical model and the inelastic scattering angular distributions were analysed with both the distorted-wave Born approximation and the Tamm-Dancoff distributions were analysed with both the distorted-wave Born approximation and the Tamm-Dancoff approximation. The analysis indicates a value of β = 0.34.

Optical model analysis of scattering of 14 MeV neutrons by light nuclei

Abstract The nuclear optical model is used to fit the elastic scattering of 14 MeV neutrons by lithium, beryllium, boron, carbon, nitrogen and oxygen. Good results are obtained for all elements except carbon. It is found that the radial parameter r0 used to define the radius of the potential well ( R = r 0 A 1 3 ) increases with decreasing mass number.

Study of the 22Ne(d, d)22Ne, 22Ne(d, p)23Ne, 22Ne(d, t)21Ne and 22Ne(p, d)21Ne reactions

Abstract The nuclear reactions 22 Ne(d, d) 22 Ne, 22 Ne(d, p) 23 Ne and 22 Ne(d, t) 22 Ne induced with 12.1 MeV deuterons and 22 Ne(p, d) 21 Ne induced with 18.2 MeV protons have been studied by employing a gas target of enriched 22 Ne and beams accelerated in the Livermore variable energy cyclotron. The results have been analysed with the nuclear optical model and DWBA calculations. The neutron-transfer reactions have been compared with the predictions of the Nilsson model. The results for the pick-up reactions going to the first three levels of 21 Ne are in good agreement with the predictions of the Nilsson model. The RPC model (rotational and particle motion with Coriolis band mixing) modified for pairing effects was employed in an effort to obtain at least a qualitative explanation of the transitions leading to 23 Ne. There are certain large discrepancies consisting of strong transitions that are predicted theoretically under a wide range of assumptions but not seen experimentally. These results indicate that further detailed calculations are necessary to understand the structure of this nucleus.

Study of the 25Mg(d,p)26Mg reaction at Ed = 8.0 MeV

Abstract The 25 Mg(d,p) 26 Mg reaction at 8.0 MeV incident deuteron energy has been studied. Data were obtained down to 0° with respect to the incident beam. Complete angular distributions were obtained for transitions leading to the ground state of 26 Mg and excited states at 1.81, 2.94 and 3.94 MeV. The state at 3.58 MeV was excited very weakly and was seen in only a few spectra. Integrated cross sections were obtained by fitting the experimental data by a sum of Legendre polynomials. The angular distributions were analysed in terms of the DWBA. The angular distribution of the transition leading to the ground state of 26 Mg has the shape of a single l = 2 stripping pattern. The other angular distributions require a sum of l = 0 and l = 2 stripping curves. The spectroscopic factors are compared with the theoretical predictions of the quasi-molecular model.

Study of 18O by 21.4 MeV alpha-particle scattering

Abstract The elastic and inelastic scattering of 21.4 MeV alpha particles by 18O has been measured. The elastic angular distribution was fitted using the nuclear optical model. The potential thus obtained was employed in a DWBA calculation and values of β1R were obtained for the 1.98 MeV level (Jπ = 2+; β2R = 0.99 fm), the 3.92 MeV level (Jπ = 2+; β2R = 0.62 fm) and the 5.09 MeV level (Jπ = 3−; β2R = 1.33 fm). The 4.45 MeV level and the 6.19 MeV level were strongly excited but could not be fitted with the usual one-step DWBA calculation.

NUMERICAL CALCULATION OF COULOMB WAVE FUNCTIONS FOR REPULSIVE COULOMB FIELDS

Abstract A description of the numerical calculation of Coulomb functions used in scattering and reaction calculations is given. A table of Coulomb functions for selected values of Coulomb parameter η over the range of 1 to 25 is also presented.

Study of the 18O(p,t)16O and 18O(p,d)17O reactions at Ep = 18.2 MeV

Abstract The nuclear reactions 18 O(p,t) 16 O and 18 O(p,d) 17 O have been studied at E p = 18.2 MeV. A gas target of enriched 18 O was used. Triton groups corresponding to the ground state of 16 O, 6.05–6.13 (unresolved), 6.92, 7.12 and 8.88 MeV levels were observed in the (p,t) reaction. The unnatural parity ( J π = 2 − ) state at 8.88 MeV was the weakest (p,t) transition observed. In the (p,d) reaction deuteron groups corresponding to the ground state of 17 O and excited states at 0.871, 3.058 and 3.846 MeV were seen. DWBA analyses of the ground state (p,t) reaction and the first three (p,d) transitions were performed. There was no evidence of a simple pick-up reaction leading to the 3.846 MeV state (J π = 5 2 − ) of 17 O.

The 30Si(p, d)29Si and 30Si(p, t)28Si reactions at 27 MeV☆

Abstract The 30 Si(p, d) 29 Si and 30 Si(p, t) 28 Si reactions have been studied using a 27 MeV proton beam from the Livermore cyclograaff. Angular distributions were obtained for energy levels to 9.7 MeV in 29 Si and 7.4 MeV in 28 Si. A DWBA analysis was performed to extract spectroscopic factors and enhancement ratios for the one- and two-neutron pick-up reactions. The results are compared with previous neutron pickup experiments and with a microscopic shell-model calculation.

Proton and deuteron induced reactions on 21Ne

Abstract The 21 Ne(d, d) 21 Ne, 21 Ne(d, p) 22 Ne, 21 Ne(p, p) 21 Ne and 21 Ne(p, d) 20 Ne reactions have been studied using deuterons of 12.2 and 14.5 MeV and protons of 14.1 MeV with an enriched 21 Ne gas target. The results have been analyzed with DWBA and coupled-channel calculations. The transfer reaction results are compared with previous work and with both the Nilsson-model and shell-model results. In general, reasonable agreement is found. The inelastic studies have been used to deduce deformation parameters. These studies indicate the need for a hexadecapole deformation in order to obtain agreement between the experimental and calculated cross sections.