D.W. Devins

Microscopic and macroscopic aspects of 135 MeV proton scattering from 16O

Abstract Differential cross sections have been measured for the scattering of 135 MeV protons from 16 O and data from the transitions to 13 states (up to 19.5 MeV excitation) have been analysed using microscopic and macroscopic nuclear reaction models. Extensive collective model calculations have been made of the transitions to all natural-parity states. The deformation parameters for the 4p4h rotational band are in good agreement with theoretical models. The inelastic scattering data from the excitation of the negative-parity states have also been analysed in the distorted-wave approximation using microscopic (shell and RPA) models of nuclear structure and with density-dependent two-nucleon t -matrices. For positive-parity states, we report the first shell-model calculation using the complete 2ħω basis space and find that the triplet of 2p2h states (4 + , 2 + , 0 + ) around 11 MeV excitation is quite well described by this model, as may be a 1 + state which is observed for the first time by proton scattering from 16 O.

Density-dependent forces and large-basis structure models in the analyses of 12C(p, p') reactions at 135 MeV

Abstract Differential cross sections have been measured for the elastic and inelastic scattering of 135 MeV protons from 12C. The data from the transitions to 9 selected states up to 18.3 MeV in excitation have been analysed using a distorted wave approximation with various microscopic model nuclear structure transition densities and free and density-dependent two-nucleon t-matrices. Clear signatures of the density dependence of the t-matrix are defined and the utility of selected transitions to test different attributes of that t-matrix when good nuclear structure models are used is established.

The spectroscopy of 13C by inelastic proton scattering

Abstract At 135 MeV incident energy, differential proton scattering cross sections have been measured for many states of 13 C, up to 23 MeV in excitation. These data are supplemented by analysing power data for states up to 10 MeV in excitation, measured at 119 MeV incident energy. Distorted wave analysis using a density-dependent form of the nucleon-nucleon interaction has provided a thorough assessment of the model predictions of the nuclear structure of many of these excited states.

The 48Ca(d→, 3He)47K reaction at 80 MeV

Abstract A high-resolution measurement of the 48Ca(d→, 3He)47K reaction has been carried out. Seventeen final states are found, up to an excitation of 8.35 MeV. The measured vector analysing powers allow spin determination for most of these states. The 2s1/2 and ld3/2 hole strengths observed are found to exhaust the respective sum rules, while 64% of the sum-rule strength for 1d5/2 hole states is found. It is surmised that the remainder of this strength resides at higher excitation energies. The amount of proton ground-state correlations is deduced from the strength of a newly observed 7/2− state in 47K.

Neutron-knockout reactions from 2H, 40Ca and 48Ca

Abstract The reactions 2H(p, pn)1H and 40,48Ca(p,pn)39,47Ca were studied at 149.5 MeV in coplanar geometries. An overall separation-energy resolution of about 1 MeV was achieved. In addition to valence neutron-hole states ( lf 7 2 , ld 3 2 , 2 s 1 2 ) , probable neutron-hole strength is seen for ld 5 2 and 1p shell knockout for both calcium targets. The 2H and 40,48Ca data are compared with PWIA and DWIA calculations, respectively. Spectroscopic factors and rms radii are extracted for neutron-hole states.

(p↘,d) analyzing‐power measurements at 95 MeV

Analyzing‐power angular distributions have been measured for prominent states excited by the 24Mg(p↘,d) reaction at 95‐MeV bombarding energy. The distributions for the previously‐known states below 6 MeV exhibit a clear j‐dependence which is most pronounced near 6° for l=1 transitions, and near 35° for l=2 transitions. The analyzing power observed for l=0 pickup reaches a value ≂90% near 20°. These spin signatures allow the identification of ‘‘deep‐hole’’ p states at 8.91. 9.67, and 10.57‐MeV excition in 23Mg as p−13/2 and of a state at 9.02 Mev as p−11/2.