F. Ihara

Polarization transfer observables for proton inelastic scattering from 12C at 0

Abstract Polarization transfer (PT) observables in the 12 C (p,p′) reaction at 0° for 392 MeV protons have been measured. The excitation strengths are decomposed into the spin-flip part and the non-spin-flip part by using the obtained PT observables. The PT observables for excitation of the 1+, T=0 and 1+, T=1 states are compared with distorted wave impulse approximation calculations. The strength ratios of the isoscalar spin-dependent term to the isovector tensor term and the isovector tensor term to the isovector spin-dependent term are reasonably consistent with the Franey and Love interaction.

Spin-isospin Responses of ^{71}Ga for Solar Neutrinos Studied by ^{71}Ga(^{3}He,t

Abstract The charge-exchange 71Ga(3He,tγ)71Ge reaction was used to study the spin-isospin (Gamow Teller: GT) excitations relevant to the axial-vector charged-weak response for solar neutrinos. High-lying GT states in 71Ge with excitation energies up to one MeV above the neutron threshold were found to have finite γ-decay branches to low-lying states. The GT strengths for relevant states and absorption rates of solar neutrinos through the 71Ga(ν, e)71Ge and 71Ga(ν,eγ)71Ge reactions were derived.

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Discrete Gamow-Teller (GT) transitions 176Yb-->176Lu at low excitation energies have been measured via the ( 3He,t) reaction at 450 MeV and at 0 degrees. For 176Yb, two low-lying states are observed, setting low thresholds Q(nu) = 301 and 445 keV for neutrino ( nu) capture. Capture rates estimated from the measured GT strengths, the simple two-state excitation structure, and the low Q(nu) in Yb-Lu indicate that Yb-based nu detectors are well suited for a direct measurement of the sub-MeV solar electron-neutrino ( nu(e)) spectrum including pp neutrinos.

)^{71}Ge Reaction

Abstract For a selective excitation of spin-flip strength, ( 6 Li, 6 He) reactions can be a useful tool, because: a) 6 Li and 6 He have ground-state spin and parity values J π = 1 + and 0 + , respectively; b) 6 He has no particle-stable excited state, thus effects from ejectile excitation can be avoided. The ( 6 Li, 6 He) experiments were performed at 100 MeV/nucleon, at which incident energy the reaction is expected to be single-step dominant. Through the analysis of the good-resolution ( 6 Li, 6 He) data on 13 C, 26 Mg, 27 Al and 58 Ni targets, the evidence for a proportional relationship between 0° cross sections and the corresponding Gamow-Teller transition strengths is examined. Suppression of non-spin flip excitations is discussed based on the hindrance of the excitation of the isobaric analog state.

Gamow-Teller strengths of the inverse beta transition Yb-176 -> Lu-176 for spectroscopy of proton-proton and other sub-MeV solar neutrinos

Polarization transfer (PT) coefficients in the 12C, 28Si(p,p′) reactions at a scattering angle of 0° are measured at Ep=392 MeV. The strength of the isoscalar central spin-dependent part (Vσ) of the effective nucleon-nucleon interaction is studied by using the sensitivity of the PT coefficients for the excitation of the 1+, T=0 state in 12C to the Vσ strength. It is found that distorted wave impulse approximation (DWIA) calculations employing the Franey and Love effective interaction well reproduce the measured PT coefficients.

(6Li,6He) reaction at 100 MeV/nucleon as a probe of spin-excitation strengths

Decay via proton emission of isobaric analog states (IAS’s) in 91 Nb was studied using the 90 Zr(α, t) reaction at E�=180 MeV. This study provides information about the damping mechanism of these states. Decay to the ground state and low-lying phonon states in 90 Zr was observed. The experimental data are compared with theoretical predictions wherein the IAS ‘single-particle’ proton escape widths are calculated in a continuum RPA approach. The branching ratios for decay to the phonon states are explained using a simple model.