B.M. Spicer

Deeply-bound hole states in 57Co and the spreading of the 1d52 hole strength distribution

In an attempt to locate the 1d52 proton hole state in 57Co we have measured the 58Ni(d, 3He)57Co reaction with 79.6 MeV vector polarized deuterons. An overall energy resolution of 50 keV was achieved with a magnetic spectrometer. The spectra show fine structure up to Ex = 11 MeV; this fact was used to define energy bins for which cross sections and analyzing powers were obtained. The latter allowed spin and parity assignments for deep-lying hole states in 57Co. Spectroscopic factors were obtained by applying standard DWBA calculations. Most of the strength above 6.6 MeV was identified as being 1d52 in nature. The running sum of Spectroscopic factors shows a linear increase implying a nearly uniform spread of the 1d52 Spectroscopic strength or a width of the 1d52 hole state comparable to the excitation energy.

Quartet structure in light nuclei

The nature of the low-lying even parity, even spin states of 4n-nuclei are discussed in terms of the quartet scheme, and many of their properties can be given by it. These states are also the low-lying states important in the collective correlations model of the giant dipole resonance, and the quartet scheme thus provides a description of them.

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.

Intermediate-energy proton scattering from 10B

Abstract Differential cross sections have been measured for 200 MeV proton scattering from 10 B. Data for six low-lying natural-parity levels below 6 MeV excitation energy are presented. Distorted-wave analysis using a density-dependent nucleon-nucleon interaction has assessed model spectroscopies of these excited states. The significance of the contribution from quadropole scattering to the elastic cross section is clearly shown.

Evidence for proton ground state correlations in48Ca

In a high resolution48Ca(d,3He) experiment at 80 MeV evidence has been found for a 7/2− state at 1.97 MeV in47K with a spectroscopic factor of C2S=0.08 corresponding to a ~4% admixture of πf2(s,d)−2 configurations in the ground state of Ca.

Gamow-Teller and dipole strength in the 208Pb(n,p) reaction

Abstract Earlier data on the 208Pb(n,p)208Ti reaction at 198 MeV has been analysed using the multipole decomposition technique, and the contributions to the spectra from L = 0 and 1 transitions determined. The L = 0 cross section has been found to be smaller than values given by the calculations of MacFarlane [3] for Gamow-Teller transitions, using three different forms for the population of single particle states about the Fermi energy. Comparison is made with GT-strength values obtained from a more recent mean field calculation of these populations, and with an older nuclear structure calculation of properties of the lead nuclei. The L = 1 strength distribution is also reported.

Spectroscopy of 14C from the 11B(α,p)14C reaction at 118 MeV

Abstract Proton angular distributions have been measured for the 11 B(α, p) 14 C reaction at 118.1 MeV. DWBA calculations employing three-nucleon semi-microscopic form factors were made for states of excitation energies ranging from 6 MeV to 21.5 MeV. The weak coupling shell model wavefunctions of Lie were used in the DWBA calculations for states of 14 C below 12 MeV excitation energy. For states above 14.8 MeV 3p-5h components in the 14 C wavefunctions are shown to play a dominant role.

The 13C(p̄, d)12C reaction at 119 MeV

Abstract Differential cross sections and analysing powers for transitions to many residual states of 12 C below 20 MeV excitation energy have been measured for the (p, d) reaction on 13 C at 119 MeV. Distorted wave Born approximation calculations using either adiabatic or conventional deuteron elastic scattering potentials were unable to adequately reproduce the cross-section and analysing power data for the strongest observed transitions. In order to improve the fits to both these sets of data it was necessary to include an imaginary spin-orbit term in the deuteron potential. The spectroscopic factors deduced in this analysis are, however, smaller than theoretical predictions. The mechanisms for the population of the observed weak residual states are discussed semi- quantitatively, and for the higher excitation energy region, a comparison to the known level structure of 12 C is made.

Isovector spin resonances in 90Y from the 90Zr(n,p)90Y reaction at 198 MeV

Proton spectra from the 90Zr(n,p)90Y reaction have been measured at laboratory angles of 0°, 3°, 6°, 8°, 13°, 17°, and 21°, for 198 MeV incident neutrons. Spectra are presented, and the separation of the spin‐flip giant resonance from the quasi‐free scattering is discussed. Results of the analysis are presented.