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We present zero-degree differential cross sections and transverse spin-transfer coefficients D{sub NN}(0{degree}) for the {sup 17,18}O({rvec p},{rvec n}){sup 17,18}F reactions at E{sub p}=118 MeV. For the transition to the {sup 17}F(g.s.) to which several multipoles contribute, the measured D{sub NN}(0{degree})={minus}0.13{plus_minus}0.05 is used to separate the Fermi and Gamow-Teller contributions at 0{degree}. The empirical Gamow-Teller strengths and the Fermi strengths are employed to estimate the solar neutrino absorption cross section in {sup 17}O and {sup 18}O. {copyright} {ital 1999} {ital The American Physical Society}

Gamow-Teller transition strengths obtained in the {sup 127}I(p,n){sup 127}Xe reaction studied at 94, 159, and 197 MeV incident proton energies are presented, and used to evaluate the efficiency of {sup 127}I as a solar neutrino detector. Excitation of the J{sup {pi}}=(3/2){sup +} first excited state at E{sub x}=0.125 MeV in {sup 127}Xe, sensitive to {sup 7}Be solar neutrinos, is evaluated. The sum of Gamow-Teller strength up to particle emission threshold and up to 20 MeV excitation energy are also reported. This paper also provides a new measurement of the Coulomb displacement energy {Delta}E{sub c}, the excitation energy of the isobaric analog state, and the centroid of the Gamow-Teller resonance in {sup 127}Xe. {copyright} {ital 1999} {ital The American Physical Society}

Double differential cross sections and analyzing powers over the quasielastic region have been measured using the ({ital {rvec p}},{ital n}) reaction on {sup 12}C and {sup nat}Pb. The data were obtained at proton energies of 495 and 795 MeV and cover momentum transfers from 1.0--2.1 fm{sup {minus}1} at 495 MeV data and from 0.0--3.5 fm{sup {minus}1} at 795 MeV. The cross section data are compared to results from a nonrelativistic reaction model that includes contributions from two-step scattering. The analyzing power measurements are compared to a recent relativistic plane-waves model.

Experimental data on the nuclear spin-isospin response in the quasifree region, measured with the charge-exchange reaction (d\ensuremath{\rightarrow},2p${[}^{1}$${\mathit{S}}_{0}$]) at Laboratoire National Saturne, are presented. The use of a tensor-polarized beam enables us to separate the tensor analyzing powers ${\mathit{T}}_{20}$ and ${\mathit{T}}_{22}$. The present publication is intended to serve as a compilation of the complete set of quasifree data with the (d\ensuremath{\rightarrow}${,}^{2}$He) reaction at 1.6 GeV bombarding energy. Data for $^{12}\mathrm{C}$ are compared to calculated cross sections and tensor-analyzing powers. The cross section in the high-energy end of the quasielastic peak is underestimated, whereas the polarization observables are reasonably well reproduced. The distortion effects are, however, found to be large, suggesting that the (d\ensuremath{\rightarrow}${,}^{2}$He) reaction is not sensitive to spin correlations in the continuum.

Double differential cross sections for ([ital p],[ital n]) quasifree scattering on [ital p]-shell nuclei, [sup 6,7]Li, [sup 10,11]B, and [sup 12,13]C, have been measured at an incident proton energy of 186 MeV between [theta][sub lab]=[theta][degree] and [theta][sub lab]=50[degree] in steps of 5[degree]. The normal polarization transfer coefficient, analyzing power, and induced polarization were also measured at [theta][sub lab]=0[degree], 15[degree], and 20[degree] using an incident proton beam of transverse polarization. Calculations by some competing quasifree models are presented and compared with the experimental results.

We compare the Gamow-Teller strength distributions for the [ital A]=37 system as measured by the [sup 37]Ca [beta][sup +] decay experiment with [sup 37]Cl ([ital p],[ital n]) experiments, considering the effect of suppression of [beta]-delayed protons from the 3.239-MeV state in [sup 37]K. We determine a range of values for the suppression of proton emission from this state for which the two measurements of strength are consistent. Recent studies of this state support this suppression and the amount of suppression is within our allowed range. Using the experimentally determined value for the suppression we are able to determine neutrino cross sections on [sup 37]Cl from [sup 8]B solar neutrinos, supernova neutrinos, and [mu][sup +] decay neutrinos. Our cross section for [mu][sup +] decay neutrinos is found to be 20% larger than the estimates of Bahcall, because of high-lying strength only recently confirmed by the [sup 37]Ca [beta][sup +] decay experiment.

The $^{12}\mathrm{C}$(n,p${)}^{12}$B reaction was studied using the white neutron source at the Los Alamos Meson Physics Facility/Weapon Neutron Research Center with a continuous incident neutron energy from 60 to 260 MeV. Double differential cross sections were measured in the angular range 11\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\le}${\mathrm{\ensuremath{\theta}}}_{\mathrm{lab}}$\ensuremath{\le}37\ifmmode^\circ\else\textdegree\fi{}. Using the neutron time-of-flight facility at the Indiana University Cyclotron Facility, we also studied the $^{12}\mathrm{C}$(p,n${)}^{12}$N reaction at ${\mathit{E}}_{\mathit{p}}$=186 MeV and the $^{12}\mathrm{C}$(p\ensuremath{\rightarrow},n\ensuremath{\rightarrow}${)}^{12}$N reaction at ${\mathit{E}}_{\mathit{p}\ensuremath{\rightarrow}}$=160 and 186 MeV. Double differential cross sections were measured between ${\mathrm{\ensuremath{\theta}}}_{\mathrm{lab}}$=0\ifmmode^\circ\else\textdegree\fi{} and ${\mathrm{\ensuremath{\theta}}}_{\mathrm{lab}}$=50\ifmmode^\circ\else\textdegree\fi{} in 5\ifmmode^\circ\else\textdegree\fi{} steps. Spin observables ${\mathit{D}}_{\mathit{N}\mathit{N}}$, ${\mathit{A}}_{\mathit{Y}}$, and P were measured at ${\mathrm{\ensuremath{\theta}}}_{\mathrm{lab}}$=5\ifmmode^\circ\else\textdegree\fi{},9\ifmmode^\circ\else\textdegree\fi{},13\ifmmode^\circ\else\textdegree\fi{} with ${\mathit{E}}_{\mathit{p}\ensuremath{\rightarrow}}$=160 MeV and ${\mathrm{\ensuremath{\theta}}}_{\mathrm{lab}}$=15\ifmmode^\circ\else\textdegree\fi{},20\ifmmode^\circ\else\textdegree\fi{} with ${\mathit{E}}_{\mathit{p}\ensuremath{\rightarrow}}$=186 MeV. Angular distributions of differential cross section and spin observables for low-lying transitions in the residual nuclei are compared with disorted-wave impulse approximation (DWIA) calculations. A multipole decomposition analysis was performed to study the giant dipole and giant spin-dipole resonances. The contributions of the quasifree reaction in the giant resonance region was subtracted. The empirical results of energy distributions for dipole (\ensuremath{\Delta}L=1) transition are compared with DWIA calculations using nuclear structure information obtained with a conventional shell model and also with a random phase approximation.

The $^{10}\mathrm{B}$(p,n${)}^{10}$C reaction was studied using the Indiana University Cyclotron Facility (IUCF) neutron time-of-flight facilities at an incident proton energy of 186 MeV between ${\mathrm{\ensuremath{\theta}}}_{\mathrm{lab}}$=0\ifmmode^\circ\else\textdegree\fi{} and ${\mathrm{\ensuremath{\theta}}}_{\mathrm{lab}}$=50\ifmmode^\circ\else\textdegree\fi{} in steps of 5\ifmmode^\circ\else\textdegree\fi{}. The IUCF neutron polarimeter was also used to measure polarization observables at ${\mathrm{\ensuremath{\theta}}}_{\mathrm{lab}}$=0\ifmmode^\circ\else\textdegree\fi{}, 15\ifmmode^\circ\else\textdegree\fi{}, and 20\ifmmode^\circ\else\textdegree\fi{} using an incident transverse polarized proton beam. Data for transitions to excited states in $^{10}\mathrm{C}$ below 7 MeV are presented. A multipole decomposition analysis is presented for unresolved states up into the continuum. Distorted wave calculations are presented for positive and negative parity transitions which are compared with data to assess spectroscopies of the $^{10}\mathrm{C}$ excited states.

A complete set of polarization-transfer observables has been measured for quasifree (p\ensuremath{\rightarrow},n\ensuremath{\rightarrow}) reactions on $^{2}\mathrm{H}$, $^{12}\mathrm{C}$, and $^{40}\mathrm{Ca}$ at a bombarding energy of 495 MeV and a laboratory scattering angle of 18\ifmmode^\circ\else\textdegree\fi{}. The data span an energy-loss range from 0 to 160 MeV, with a corresponding momentum transfer range of ${\mathit{q}}_{\mathrm{c}.\mathrm{m}.}$=1.7--1.9 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$. The laboratory observables are used to construct partial cross sections proportional to the nonspin response and three orthogonal spin responses. These results are compared to the transverse spin response measured in deep inelastic electron scattering and to nuclear responses based on the random phase approximation. The polarization observables for all three targets are remarkably similar and reveal no evidence for an enhancement of the spin-longitudinal nuclear response relative to the spin-transverse response. These results suggest the need for substantial modifications to the standard form assumed for the residual particle-hole interaction.

We report a measurement of the Gamow-Teller (GT) strength distribution for $^{40}\mathrm{Ar}\ensuremath{\rightarrow}^{40}\mathrm{K}$ using the ${0}^{\ifmmode^\circ\else\textdegree\fi{}}(p,n)$ reaction. The measurement extends observed GT strength distribution in the $A=40$ system up to an excitation energy of $~8$ MeV. In comparing our results with those from the $\ensuremath{\beta}$ decay of the isospin mirror nucleus $^{40}\mathrm{Ti}$, we find that, within the excitation energy region probed by the $\ensuremath{\beta}$-decay experiment, we observe a total GT strength that is in fair agreement with the $\ensuremath{\beta}$-decay measurement. However, we find that the relative strength of the two strongest transitions differs by a factor of $~1.8$ in comparing our results from ($p,n$) reactions with the $\ensuremath{\beta}$ decay of $^{40}\mathrm{Ti}$. Using our results we present the neutrino-capture cross section for $^{40}\mathrm{Ar}$.

Zero-degree cross sections have been measured for the {sup 11}B({ital p},{ital n}){sup 11}C reaction at bombarding energies of {ital E}{sub {ital p}}=160, 200, 494, 644, and 795 MeV. In addition, spectra have been obtained at laboratory scattering angles of 3{degree} and 5{degree} at 494 MeV, and the transverse spin-flip probability at zero degrees has been measured for {ital E}{sub {ital p}}=160 MeV. These data are used to obtain estimates of the Gamow-Teller transition strength to final states in {sup 11}C up to an excitation energy of {ital E}{sub {ital x}}{approx equal}14 MeV. The uncertainty (1 standard deviation) in the extracted transition strengths is estimated to be in the range (2--8)%. Measured cross sections for the first four excited states in {sup 11}C have been compared to distorted-wave impulse approximation calculations. In this comparison, no evidence is found in the cross-section data for certain effects associated with knock-on exchange and noncentral interactions.

Differential-cross-section distributions for the {sup 7}Li({ital p},{ital n}){sup 7}Be(g.s.+0.43-MeV) reaction have been measured for {ital E}{sub {ital p}}=80, 120, 160, 200, 494, 644, and 795 MeV. These distributions have been integrated and normalized to independent values for the total cross section obtained from parametrizations of {sup 7}Li({ital p},{ital n}) activation measurements. Zero-degree cross sections obtained from this normalization are reported.

Differential cross section angular distributions for the $^{6,7}\mathrm{Li}$(p,n${)}^{6,7}$Be reactions have been measured at energies between 60 and 200 MeV. The experimental angular distributions are analyzed using a microscopic distorted wave impulse approximation. The results of self-consistent microscopic distorted wave calculations based on a complete set of weak and electromagnetic data for the mass 6 and 7 systems are also presented. Total observed Gamow-Teller strength up to about 40 MeV excitation energy is reported. Energy dependence of the \ensuremath{\sigma}\ensuremath{\tau} and \ensuremath{\tau} effective interaction terms are presented up to 200 MeV. The measured (p,n) cross sections for the $^{7}\mathrm{Be}$ (g.s.) and $^{7}\mathrm{Be}$ (0.43 MeV) transitions are used to obtain the branching ratio of the $^{7}\mathrm{Be}$ (g.s.) decay to the g.s. and 0.478 MeV states in $^{7}\mathrm{Li}$. Zero degree polarization transfer (${\mathit{D}}_{\mathit{N}\mathit{N}}$) data at ${\mathit{E}}_{\mathit{p}}$=80, 120, 160, and 200 MeV are reported for the $^{6}\mathrm{Li}$(p,n${)}^{6}$Be (g.s.) and for the $^{7}\mathrm{Li}$(p,n${)}^{7}$Be (g.s.+0.43 MeV) reactions. Energy dependence of total and zero degree differential cross section for the $^{7}\mathrm{Li}$(p,n${)}^{7}$Be (g.s.+0.43 MeV) transitions are reported. Finally a comparison is presented for the (n,p), (p,p'), and (p,n) reaction in $^{6}\mathrm{Li}$ populating isospin triplets.

In this paper, we present a complete set of polarization-transfer observables measured at 197 MeV in the quasifree region for $(\stackrel{\ensuremath{\rightarrow}}{p},\stackrel{\ensuremath{\rightarrow}}{n})$ reactions on ${}^{2}\mathrm{H}$ and ${}^{3,4}\mathrm{He}$ targets. Data were obtained at laboratory scattering angles of $13\ifmmode^\circ\else\textdegree\fi{},$ $24\ifmmode^\circ\else\textdegree\fi{},$ $37\ifmmode^\circ\else\textdegree\fi{},$ and $48\ifmmode^\circ\else\textdegree\fi{}$ for the ${}^{2}\mathrm{H}$ target and at $13\ifmmode^\circ\else\textdegree\fi{}$ and $37\ifmmode^\circ\else\textdegree\fi{}$ for the ${}^{3,4}\mathrm{He}$ targets. The data span an energy-loss range up to 150 MeV, with a corresponding momentum-transfer range $q=0.75--2.4 {\mathrm{fm}}^{\ensuremath{-}1}.$ The polarization-transfer observables are used to calculate the center-of-mass polarization observables. The empirical results for the ${}^{2}\mathrm{H}$ target are compared to the observables obtained from the free nucleon-nucleon database and with Faddeev-type calculations. No discernible differences are observed in either the values of polarization-transfer observables or in the center-of-mass polarization observables among the three nuclei studied in this paper.

C. Hautala, J. Rapaport, M. Palarczyk, D. L. Prout, D. A. Cooper, G. Savopulos, B. Anderson, A. Baldwin, C. C. Foster, C. D. Goodman, K. Hicks, R. Howes, M. S. Islam, B. A. Luther, D. M. Manley, R. Madey, E. Sugarbaker, T. N. Taddeucci, I. Van Heerden,* J. Watson, X. Yang, and W. -M. Zhang Ohio University, Athens, Ohio 45701 Henryk Niewodniczanski Institute of Nuclear Physics, 31-342 Krakow, Poland Indiana University Cyclotron Facility, Bloomington, Indiana 47405 Department of Physics, Kent State University, Kent, Ohio 44242 The Ohio State University, Columbus, Ohio 43210 Ball State University, Muncie, Indiana 47306 Concordia College, Moorhead, Minnesota 56562 Los Alamos National Laboratory, Los Alamos, New Mexico 87545 ~Received 31 July 2001; published 19 February 2002!

We examine a broad resonance in the $0\ifmmode^\circ\else\textdegree\fi{}$ ${}^{208}\mathrm{Pb}{(p,n)}^{208}\mathrm{Bi}$ and ${}^{90}\mathrm{Zr}{(p,n)}^{90}\mathrm{Nb}$ cross section spectra obtained at 795 MeV incident energy that appears at 32 MeV excitation energy in ${}^{208}\mathrm{Bi}$ and ${}^{90}\mathrm{Nb}.$ Earlier data taken at 200 MeV incident energy using the same reactions show no evidence for this resonance. We present theoretical results indicating that the spin isovector monopole predicted at this excitation energy is barely excited at 200 MeV while it is strongly excited at the higher energy. To further investigate this structure we have measured the first complete set of polarization-transfer observables for ${}^{\mathrm{nat}}\mathrm{Pb}$ at $0\ifmmode^\circ\else\textdegree\fi{}$ using the $(\stackrel{\ensuremath{\rightarrow}}{p},\stackrel{\ensuremath{\rightarrow}}{n})$ reaction at 795 MeV. The data show this resonance is predominantly a spin flip $\ensuremath{\Delta}S=1$ excitation giving strong supporting evidence for assigning this resonance as the spin isovector monopole.

Cross-section and analyzing-power data are presented for the $^{12}\mathrm{C}$($\stackrel{\ensuremath{\rightarrow}}{p}$,${p}^{\ensuremath{'}}$)$^{12}\mathrm{C}$ reaction at a bombarding energy of 120 MeV. Calculations are made in the distorted-wave impulse approximation with an antisymmetrized on-shell $t$ matrix obtained from nucleon-nucleon scattering amplitudes at 140 MeV. The results are in much better agreement with the data for the cross sections than for the analyzing powers. Significant discrepancies with the data at large momentum transfers are found. Analysis of the contributions for the observed ${2}^{\ensuremath{-}}$ transitions shows strong sensitivity to the underlying configurations and appear to be well described by the shell-model wave functions of Millener and Kurath.

The /sup 40/Ca(p,n) reaction at E/sub p/ = 159.3 MeV excites a state at E/sub x/ = 2.7 +- 0.1 MeV in /sup 40/Sc. The energy dependence and differential cross section angular distribution for this reaction indicate that this state is the T/sub z/ = -1 analog of a known 1/sup +/ state at E/sub x/ = 10.32 MeV in /sup 40/Ca. We find that the Gamow-Teller strength for this 0/sup +/..-->..1/sup +/ (p,n) transition is B(GT) = 0.21 +- 0.04. Comparison of B(GT) to B(M1)up-arrow for the analogous M1 transition in /sup 40/Ca indicates a substantial orbital-current contribution to the M1 strength. The /sup 40/Ca(p,n) reaction also strongly excites a 2/sup -/ state at E/sub x/ = 0.77 MeV in /sup 40/Sc. Good agreement is found between properly normalized distorted-wave impulse approximation calculations and the measured differential cross sections for this transition at 159.3 MeV.

Angular distributions for the ground-state (..delta..J/sup ..pi../ = 1/sup +/) and 0.96-MeV (..delta..J/sup ..pi../ = 2/sup +/) transitions in the /sup 12/C( p,n)/sup 12/N reaction have been measured at incident energies of 120, 160, and 200 MeV. The measured values of the differential cross section align themselves into smooth curves independent of incident energy when converted into plane-wave cross section values and plotted versus momentum transfer. This information supports the hypothesis that the spin-isospin term of the effective interaction is almost energy independent in this energy region. Microscopic distorted-wave impulse approximation calculations are presented.

Differential cross sections and analyzing powers for the (p\ensuremath{\rightarrow},n) reaction on carbon isotopes have been measured for angles up to ${\ensuremath{\theta}}_{\mathrm{lab}=50}$\ifmmode^\circ\else\textdegree\fi{} using 160 MeV protons. The angular distributions for the stronger transitions are compared with the results of distorted-wave impulse approximation calculations which utilize transition densities from existing shell model calculations. The total observed Gamow-Teller strength is also compared with the shell model predictions. In addition, the shapes of these angular distributions are discussed emphasizing decomposition into longitudinal, transverse, and non-normal-parity-transfer components. Some comparisons of the present (p,n) data with corresponding (p,p') data and with other relevant (p,n) data are also made.

Measurements of the angular distributions of the single charge exchange reactions to isobaric analog states for /sup 13/C(..pi../sup +/,..pi../sup 0/)/sup 13/N and /sup 15/N(..pi../sup +/,..pi../sup 0/)/sup 15/O at 165 MeV are described. The two angular distributions are very similar. The shapes are reproduced by semiphenomenological isobar-doorway calculations and by second-order coupled channels calculations. The calculated magnitudes are low by about a factor of 2. Phenomenological calculations that agree with small-angle excitation functions do not reproduce the angular distributions. The measurements are consistent with older angle-integrated cross sections for /sup 13/C.

The cross section and transverse polarization transfer for the $^{2}\mathrm{H}$(p,n)2p reaction at ${E}_{\mathrm{p}=160}$ MeV and theta=0\ifmmode^\circ\else\textdegree\fi{} have been measured with good energy resolution (1 MeV). An asymmetric peak shape characteristic of the $^{1}\mathrm{S}_{0}$ final-state interaction of the residual two-proton system has been clearly observed. The measured transverse polarization transfer coefficient for this peak is ${D}_{\mathrm{NN}}$(0?(de)=-0.43\ifmmode\pm\else\textpm\fi{}0.04. A simple impulse approximation calculation including the $^{1}\mathrm{S}_{0}$ final-state interaction reproduces the main features of the observed peak shape and polarization transfer. Small discrepancies observed in the peak tail region can be accounted for by including the $^{3}\mathrm{P}_{0}$,1,2 final state interaction.

The quenching factor for M1 strength in the Zr isotopes recently deduced by Toki, Cha, and Bertsch is shown to be based on a false assumption concerning the energy dependence of optical-model distortion effects. When the correct energy dependence is accounted for the previously deduced quenching is increased by a factor of about 2.

The transverse polarization transfer for the $^{90}\mathrm{Zr}$(p,n) reaction has been measured for ${E}_{\mathrm{p}=160}$ MeV and theta=0\ifmmode^\circ\else\textdegree\fi{}. A sequence of alternating unnatural parity and natural parity excitations is clearly revealed. Some of the observed features are consistent with the known or predicted excitation energies of \ensuremath{\Delta}L=0 and \ensuremath{\Delta}L=1 resonances.