C.C. Foster

Energy Systematics of the Giant Gamow-Teller Resonance and a Charge-Exchange Dipole Spin-Flip Resonance

Energy systematics of the giant Gamow-Teller resonance and a charge-exchange resonance excited by a L = 1, S = 1 interaction are presented. Plots of the energy separation between each resonance and the IAS versus (N − Z)A can be represented approximately by linear functions.

Excitation of giant spin-isospin multipole vibrations in 54, 56Fe and 58, 60Ni

Data on (p,n) reactions at 120 and 160MeV have been used to study the excitation of spin-isospin multipole vibrations in 54, 56Fe and 58, 60Ni. In particular, transitions characterized by L = 0 transfer are identified as spin-isospin transitions (excitation of Gamow-Teller states) or as isospin transitions (excitation of isobaric analog states). An effort is made to estimate Gamow-Teller strength, B(GT), at excitation energies between 20–40 MeV. A comparison between GT and M1 strengths is presented for 58, 60Ni. Shell-model calculations for total strengths, Σ B(GT), are compared with the observed results.

Spin-dipole strength in 12N

Abstract Data are presented for the 12 C(p, n) 12 N reaction at 120, 160 and 200 MeV. Angular distributions at 160 MeV show that the spectrum between 2 and 17 MeV excitation energy is dominated by l = 1 spin excitations. The (p, n) spectrum for l = 1 transitions is calculated based on a Cohen-Kurath type of shell-model calculation. The shape of the calculated spectrum agrees well with the experimental spectrum, but with a factor of 2 larger cross section. This is consistent with electron-scattering data for the 19.4 MeV state in 12 C, the analogue of the 4.2 MeV state in 12 N. Two broad structures at 4 and 7 Me V are identified as being mainly 2 − and 1 − states.

Electron capture strength for Ni 60 , 62 and Ni 58 , 60 , 62 , 64 ( p , n ) Cu 58 , 60 , 62 , 64 reactions at 134.3 MeV

Background: The strength of electron capture for medium mass nuclei has a significant effect on the evolution of supernovae. There is insufficient knowledge of these strengths and very little data for important radioactive nuclei. Purpose: Determine whether it is feasible to obtain EC strength from studies of T{sub o}+1 excitations in (p, n) reactions, and whether this might yield information for radioactive nuclei. Methods: Cross sections for the {sup 58,60,62,64}Ni(p, n){sup 58,60,62,64}Cu reactions were measured over the angular range of 0.3 deg. to 11.6 deg. at 134.3 MeV using the IUCF neutron time-of-flight facility. Results: The T{sub o}+1 excitations in {sup 60,62}Ni were identified by comparison with inelastic proton scattering spectra, their B(GT) were extracted, and the corresponding electron capture rates in supernovae were calculated. Data from the TRIUMF (n, p) experiments at 198 MeV were reanalyzed; the electron capture rates for the reanalyzed data are in moderately good agreement with the higher resolution (p, n) results, but differ in detail. The possibility of future measurements with radioactive nuclei was considered. Conclusions: It may be possible to obtain low-lying electron capture strength for radioactive nuclei by studying (p, n) reactions in inverse kinematics.

12C(p,n)12N reaction at 135 MeV.

We report observations from the (p,n) reaction on

Neutron transition density for the lowest 2+ state of 18O

^{12}\mathrm{C}

Excitation of Gamow-Teller resonances in A=58 nuclei

at 135 MeV. The experiment was performed with the beam-swinger neutron time-of-flight system at the Indiana University Cyclotron Facility. Neutrons were detected in large-volume plastic scintillation detectors located in three detector stations at 0\ifmmode^\circ\else\textdegree\fi{}, 24\ifmmode^\circ\else\textdegree\fi{}, and 45\ifmmode^\circ\else\textdegree\fi{} with respect to the undeflected beam line; the flight paths were 91 m, 91 m, and 74 m, respectively. Overall time resolutions of about 825 ps provided energy resolutions of about 350 keV in the first two stations and about 425 keV in the third station. The angular distributions for states with excitation energies up to 10 MeV are presented and comparisons are made with DWIA calculations that use one-body density matrices from 0\ensuremath{\Elzxh}\ensuremath{\omega} and 1\ensuremath{\Elzxh}\ensuremath{\omega} shell-model calculations. New information is deduced on the excitation energies, widths, and spin-parity assignments for several energy levels of

Gamow-Teller strength distribution in 81Kr and the consequences for a 81Br solar neutrino detector

^{12}\mathrm{N}

Splitting of the Dipole and Spin-Dipole Resonances

. \textcopyright{} 1996 The American Physical Society.

C12(p,n)12N reaction at 135 MeV

Abstract Scattering of 135 MeV protons is used to fit an expansion in radial basis functions of the neutron transition density for the lowest 2 + state of 18 O. The narrow error envelope shows good radial sensitivity. The results are consistent with electromagnetic decay data for the mirror transition in 18 Ne.