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Discrete Gamow-Teller (GT) transitions ${}^{176}\mathrm{Yb}{\ensuremath{\rightarrow}}^{176}\mathrm{Lu}$ at low excitation energies have been measured via the ( ${}^{3}\mathrm{He},t$) reaction at 450 MeV and at $0\ifmmode^\circ\else\textdegree\fi{}$. For ${}^{176}\mathrm{Yb}$, two low-lying states are observed, setting low thresholds $Q(\ensuremath{\nu})\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}301$ and 445 keV for neutrino ( $\ensuremath{\nu}$) capture. Capture rates estimated from the measured GT strengths, the simple two-state excitation structure, and the low $Q(\ensuremath{\nu})$ in Yb-Lu indicate that Yb-based $\ensuremath{\nu}$ detectors are well suited for a direct measurement of the sub-MeV solar electron-neutrino ( ${\ensuremath{\nu}}_{e}$) spectrum including $\mathrm{pp}$ neutrinos.

The inclusive 2(3He,t) reaction has been studied at 2 GeV for energy transfers up to 500 MeV and scattering angles from 0.250 up to 40. Data are well reproduced by a model based on a coupled-channel approach for describing the NN and NΔ systems. The effect of final state interaction is important in the low energy part of the spectra. In the delta region, the cross-section is very sensitive to the effects of Δ-N interaction and ΔN → NN process. The latter has also a large influence well below the pion threshold. The calculation underestimates the experimental cross-section between the quasi-elastic and the delta peaks; this is possibly due to projectile excitation or purely mesonic exchange currents.

Threshold measurements of the associated strangeness production reactions pp --> pK(+)Lambda and pp --> pK(+)Sigma(0) are presented. The most remarkable feature of the data is that at the same excess energy the total cross section for the Sigma(0) production appears to be about a factor of 28(-9)(+6) smaller than for the Lambda particle. It is concluded that strong Sigma(0)p final state interactions, and in particular the Sigma N --> Lambda p conversion reaction, are the likely cause of the depletion in the Sigma signal. This hypothesis is in line with other experimental evidence in the literature.

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}

The $pp \to pp \eta^{\prime}$ (958) reaction has been measured at COSY using the internal beam and the COSY-11 facility. The total cross sections at the four different excess energies \mbox{$ Q = ~1.5 ~MeV, ~1.7 ~MeV, ~2.9 ~MeV,$ and $ ~4.1 MeV$} have been evaluated to be \mbox{$ \sigma = 2.5 \pm 0.5~nb$, $~~~ 2.9 \pm 1.1~nb$, $~~~ 12.7 \pm 3.2~nb$, ~ and $~~~ 25.2 \pm 3.6 ~nb $}, respectively. In this region of excess energy the $\eta^{\prime}$ (958) cross sections are much lower compared to those of the $\pi ^0$ and $\eta$ production.

The energy dependence of the total cross section for the pp \to pK^+\Lambda reaction was measured in the threshold region covering the excess energy range up to 7MeV. Existing model calculations describe the slope of the measured cross sections well, but are too low by a factor of two to three in rate. The data were used for a precise determination of the beam momentum of the COSY-synchrotron.

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.

We report measurements of spin correlations and analyzing powers in $^{3}\stackrel{\ensuremath{\rightarrow}}{\mathrm{He}}(\stackrel{\ensuremath{\rightarrow}}{p}, 2p)$ and $^{3}\stackrel{\ensuremath{\rightarrow}}{\mathrm{He}}(\stackrel{\ensuremath{\rightarrow}}{p}, pn)$ quasielastic scattering as a function of momentum transfer and missing momentum at 197 MeV using a polarized internal target at the Indiana University Cyclotron Facility Cooler Ring. At sufficiently high momentum transfer we find $^{3}\stackrel{\ensuremath{\rightarrow}}{\mathrm{He}}(\stackrel{\ensuremath{\rightarrow}}{p}, pn)$ spin observables are in good agreement with free $p\ensuremath{-}n$ scattering observables, and therefore that $^{3}\stackrel{\ensuremath{\rightarrow}}{\mathrm{He}}$ can serve as a good polarized neutron target. The extracted polarizations of nucleons in $^{3}\stackrel{\ensuremath{\rightarrow}}{\mathrm{He}}$ at low missing momentum are consistent with Faddeev calculations.

We describe the first experiment to use a polarized internal gas target and polarized beam in a storage ring. A laser optically pumped polarized He internal gas target has been used with circulating beams of 197-414 MeV polarized protons to carry out an extensive set of measurements of spin dependent scattering. A large acceptance non-magnetic detector system consisting of wie-chambers, scintillators and microstrip detectors was used to detect protons, neutrons, deuterons, and He-3 nuclei from the beam-target interaction. It is demonstrated that these techniques result in low backgrounds (< 1%) due to scattering from species other than the polarized target gas and allow detection of low energy recoiling nuclei. Specific issues such as interfacing the experiment to the storage ring and monitoring the luminosity and polarizations are discussed in detail.

Complete sets of polarization transfer coefficients have been measured for quasifree ([ital [rvec p]],[ital [rvec n]]) scattering from [sup 2]H, [sup 12]C, and [sup 40]Ca at 494 MeV and scattering angles of 12.5[degree], 18[degree], and 27[degree] ([ital q]=1.2,1.7,2.5 fm[sup [minus]1]). These measurements yield separated transverse ([sigma] [times]/I[ital q]) and longitudinal ([sigma] [center dot]/I[ital q]) isovector spin responses. Comparison of the separated responses to calculations and to electron-scattering responses reveals a strong enhancement in the spin transverse channel. This excess transverse strength masks the effect of pionic correlations in the response ratio.

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 present ( p , n ) spin observable measurements in the delta region of excitation taken on the targets 2H and 12C at 0° and 795 MeV proton energy. These observables have been used to form the spin-longitudinal and spin-transverse cross sections. Good agreement is found between experiment and theory in the spin-longitudinal channel.

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 polarization transfer observable [ital D][sub [ital L][ital L]](0[degree]) has been measured for [sup 2]H([ital [rvec p]],[ital [rvec n]])2[ital p], [sup 12]C([ital [rvec p]],[ital [rvec n]])[sup 12]N, and [sup 14]C([ital [rvec p]],[ital [rvec n]])[sup 14]N reactions with beam energies of 318 and 494 MeV. The deuterium results are in close agreement with free [ital NN] scattering constrained to the [Delta][ital J][sup [pi]]=1[sup +] channel. The results for the carbon targets, however, are systematically more negative than those for deuterium, which suggests a difference between the free and effective nucleon-nucleon interactions. Such a medium modification of the spin-dependent interaction may have important implications for intepretation of other intermediate-energy scattering experiments.

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.

A complete set of polarization transfer observables for quasifree scattering in the ({rvec p}, {rvec n}) reaction at 495 MeV is reported. Measurements were carried out on CD{sub 2}, natural carbon, and calcium targets at a momentum transfer of 1.72 fm{sup {minus}1} using the new Neutron Time-of-Flight facility at LAMPF. The spin-longitudinal and spin-transverse responses are extracted from the data. The ratio of these responses are compared to DWIA-RPA calculations in which the particle-hole interaction is taken to be of the form g{prime}+{pi}+{rho}. No evidence for these RPA correlations is seen in the data at this momentum transfer. 8 refs., 2 figs.

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 $^{40}\mathrm{Ar}$.

Data for the (3He, t) reaction at 900 MeV and 2 GeV on the targets 26Mg, 40Ca, 48Ca, 54Fe, 90Zr and 208Pb are presented. A multipole decomposition for the data at 900 MeV has been made and the different distributions have been analysed. From the L = 0 cross section the Gamow-Teller strength distributions are extracted and compared with (p, n) data. The L = 1 and 2 distributions are analysed in a schematic model which describes the general systematics fairly well. The spectra at 2 GeV and Θ = 4° show for all targets a well-developed quasi-elastic peak. The A-dependence of the cross section is analysed in a simple model.

Cross sections and analyzing powers have been measured for 12C(p, n) at 494 MeV and 795 MeV and for Pb(p, n) at 795 MeV. The data span an energy loss range of at least 200 MeV, vhich is sufficient to clearly reveal the large peak associated with quasifree neutron knockout. The kinematics, cross section and analyzing power for this peak are compared to the corresponding observables for free nucleon-nucleon scattering and to the observables calculated with a relativistic Fermi-gas model.

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.

Cross sections at 0{degree} for the pure Fermi (0{sup +}, 2.31, MeV) and Gamow-Teller (1{sup +}, 3.95 MeV) states in the {sup 14}C({ital p},{ital n}){sup 14}N reaction have been measured at {ital E}{sub {ital p}}=494, 644, and 795 MeV using the LAMPF neutron time-of-flight facility with a new 617-m neutron flight path. The measured cross sections per unit transition strength, {cflx {sigma}}, provide a measure of the isovector spin-flip and non-spin-flip central components of the effective nucleon-nucleon interaction. Cross sections and the ratio {ital R}{sup 2}={cflx {sigma}}{sub GT}/{cflx {sigma}}{sub F} are compared to lower-energy measurements and to calculations using a free {ital NN} {ital t} matrix.

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.

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 sections for the 90,92,94Zr(p,n) reactions were measured at energies of 79.2 and 119.4 MeV. A phenomenological model was developed to describe the variation with bombarding energy of the position of the L=1 peak observed in these and other (p,n) reactions. The model yields the splitting between the giant dipole and giant spin dipole resonances. Values of these splittings are obtained for isotopes of Zr and Sn and for 208Pb., 14 pages, 4 figures

Using the neutron time-of-flight facility at the Indiana University Cyclotron Facility we have studied ({ital p},{ital n}) reactions on the light nuclei {sup 6,7}Li, {sup 10,11}B, and {sup 12,13}C. Double differential cross sections have been measured between {theta}{sub lab}=0{degree} and 50{degree} in 5{degree} intervals, at {ital E}{sub {ital p}}=186 MeV. Contributions of the quasifree reaction in the giant resonance region are estimated. Energy spectra of {Delta}{ital L}=1 transitions have been extracted using multipole decomposition analysis. The resulting {Delta}{ital L}=1 spectra are compared with results of photonuclear reactions. Empirical results are also compared with distorted wave impulse approximation calculations.

We examine a new feature of the 0° (p,n) cross section spectra that appears at 35 MeV energy loss in Pb and Zr. To further investigate this structure we have measured a complete set of spin transfer observables for natPb at 0° using the (p↘,n↘) reaction at 795 MeV.

We present (p↘,n↘) spin observable measurements in the quasielastic and quasifree delta region of excitation taken on the targets 2H and 12C at 0° and 795 MeV proton energy. These observables have been used to form the spin–longitudinal (σ⋅q) and spin–transverse (σ×q) cross sections. Good agreement is found between experiment and theory in the spin–longitudinal channel.

Measurements of analyzing powers and spin correlation parameters for 3He(p↘,2p) and 3H↘e(p↘,pn) quasielastic scattering have been carried out using a polarized internal 3He target and a stored, polarized proton beam. They were made over a wide kinematic range with a proton energy of 197 MeV and a large acceptance detector system which allowed the simultaneous measurement of both reactions. At momentum transfers sufficiently high to minimize rescattering effects, the (p,pn) results are in agreement with PWIA calculations. The (p,2p) results were found to be less sensitive to kinematic conditions and are also in agreement with calculations.

We report the first measurement of analyzing powers and spin correlation parameters using a storage ring with both beam and internal target polarized. Spin observables were measured for elastic scattering of 45 and 198 MeV protons from polarized [sup 3]He nuclei in a new laser-pumped internal gas target at the Indiana University Cyclotron Facility Cooler Ring. Scattered protons and recoil [sup 3]He nuclei were detected in coincidence with large acceptance plastic scintillators and silicon detectors. The internal-target technique demonstrated in this experiment has broad applicability to the measurement of spin-dependent scattering in nuclear and particle physics.

A comparison is made of the recent {beta}{sup +}-decay measurements of Garcia {ital et} {ital al}. and the 1981 {sup 37}Cl({ital p},{ital n}){sup 37}Ar measurements of Rapaport {ital et} {ital al}. in order to see whether the experiments are consistent. Garcia {ital et} {ital al}. were not able to determine the amount of Gamow-Teller strength in the isobaric analog state (IAS) or the Coulomb mixing of Fermi strength to a state near the IAS, and were forced to determine the amount of Gamow-Teller strength in the daughter 1371 keV state by making the branching ratios sum to unity. This approach leaves a range of possible values open for these quantities which we investigate. We find that the experiments could be consistent within a theoretically unlikely part of this range. We also examine the effect of this range of allowed values on solar and supernova neutrino cross sections of {sup 37}Cl and find weak dependence on the uncertainties described here. We discuss how the consistency of the two experiments can be tested more conclusively.

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 reaction 42 Ca(p,n) 42 Sc at E p = 160 MeV is used to measure the Gamow-Teller (GT) strength function. Normalization of the dominant peak in the (p,n) spectrum to B (GT) determined from the analogous transition in the beta decay of 42 Ti renders the strength function absolute, and the total measured stregth is about half of the minimum value required for a T = 1 nucleus. Shell model calculations are presented which reproduce the shape of the strength function, but overpredict the absolute measured strength by about a factor of two. Evidently the missing strength has been moved out of the region of nucleon particle-hole excitations, and quenching, due possibly to Δ 33 coupling, is indicated. Symmetry implications of an observed strong suppression of the T > component of the GT strength are discussed.

Data for the Δ excitation by the (3He,t) reaction at 2.0 GeV on various nuclei are presented together with results on 12C at 1.5 and 2.3 GeV. The Δ peak position and width are found to be target mass independent. Comparison with the p(3He,t) Δ++ reaction, however, shows a shift of the position in energy of the Δ peak. Implications of these results are discussed.

The 58Ni(p,n)58Cu reaction has been studied at 120 MeV and 160 MeV incident energies. States in 58Cu with Gamow-Teller (GT) strength, identified by its L=0 angular distribution, have been observed up to an excitation energy of ∼14 MeV. The excitation of a broad resonance at ∼9 MeV excitation is identified as the main T=1 component of the GT strength in 58Cu. Comparison with shell model calculations using an fp model space indicates that the GT strength cannot be clearly resolved in terms of its T=0, 1 and 2 components. We find that the sum of the experimentally observed GT strength is ∼55% of the theoretically predicted value. Comparison is made with published M1 results from the 58Ni(e,e′) reaction.

Data are presented for the (/sup 3/He, t) reaction at energies of 600 MeV, 1.2 GeV, and 2 GeV on targets /sup nat/C, /sup 54/Fe, and /sup 89/Y. The low--excitation-energy regions of the spectra are dominated by isospin-spin excitations. Cross-section calculations in distorted-wave impulse approximation with parameters from NN data account reasonably well for the data. At 2-GeV bombarding energy a strong excitation of the ..delta.. resonance is observed for all targets.

Neutron spectra from $^{37}\mathrm{Cl}$($p$,$n$)$^{37}\mathrm{Ar}$ at ${E}_{p}=120$ MeV are measured in the angular range 0\ifmmode^\circ\else\textdegree\fi{}-30\ifmmode^\circ\else\textdegree\fi{}. Neutron groups characterized with $L=0$ transfer are obtained up to approximately 12-MeV excitation energy in $^{37}\mathrm{Ar}$. From the observed 0\ifmmode^\circ\else\textdegree\fi{} cross section the Gamow-Teller strengths for $^{37}\mathrm{Cl}$\ensuremath{\rightarrow}$^{37}\mathrm{Ar}$ transitions are obtained which are directly related to neutrino absorption by $^{37}\mathrm{Cl}$. The cross section for $^{8}\mathrm{B}$ solar neutrinos incident on $^{37}\mathrm{Cl}$ is reported.

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.

A shell-model study of the total Gamow-Teller (GT) distribution for the 26 Mg → 26 Al transition has yielded good agreement with the 0° experimental (p, n) results when normalized to the β-decay rates of the two lowest-lyiong 1 + states in 26 Al. This normalization corresponds to a GT quenching of ≈40%, in good agreement with the Δ-isobar model prediction of Bohr and Mottelson

We have succeeded in measuring at 0\ifmmode^\circ\else\textdegree\fi{} and small angles the energy spectra for the (d,2p${[\mathrm{}}^{1}$${S}_{0}$]) reaction (with the two protons in the singlet S state) at 650 MeV and 2 GeV. It is demonstrated that the reaction is a one-step process that can be used to study isospin-spin excitations. The \ensuremath{\Delta} excitation is very clearly observed. A shift down in energy of the \ensuremath{\Delta} peak from the proton to the $^{12}\mathrm{C}$ target is observed. The experiments are performed with a tensor polarized beam and the tensor analyzing power for the p(${d}_{\mathrm{pol}}$,${\mathrm{}}^{2}$He)n reaction at 2 GeV is given.

The (p, n) reactions on 19 F and 39 K targets have been studied at 120 MeV and 160 MeV using the Indiana University Cyclotron time-of-flight facility. States up to 12 MeV excitation energy have been observed and angular distributions for these neutron groups are presented. The ground-state mirror transitions have accurately measured ft values. This information is used to normalize the zero-degree energy spectra to a scale of Gamow-Teller (GT) transition probability to obtain GT strenghts to excited states. The experimental sum GT strengths are smaller than the sum-rule-limit values showing strong evidence for GT quenching.

The evidence for a useful proportionality relationship between 0° (p, n) cross sections and the corresponding Gamow-Teller and Fermi beta-decay transition strengths is examined in detail. A simple parameterization for small momentum transfer L = 0 transitions is developed and used in the analysis of (p, n) data in the bombarding energy range 120–200 MeV. The parameterization describes the (p, n) differential cross section in terms of momentum transfer, energy loss, mass number, and bombarding energy and provides a straightforward way of extrapolating to zero momentum transfer. It is found that a single proportionality constant can serve to relate all Gamow-Teller transitions originating from the same target nucleus. The target dependence of this proportionality constant, however, is found to be unpredictable at the 20%–50% level, even within isotopic chains. Such large variations cannot be easily explained in the context of the standard single-step direct-reaction distorted-waves impulse approximation model.

Data are presented for the p(3He,t)Δ++ reaction at 2.0, 2.3 and 1.5 GeV. The reaction specifically excites the Δ++ with very little yield outside the resonance. The data are analysed as one pion exchange and the hadronic form factor for the 3He−1 system is extracted and compared with the magnetic form factor from electron scattering.

The magnetic form factor of /sup 41/Ca has been measured by elastic electron scattering in the momentum-transfer range between 1.8 and 3.3 fm/sup -1/. The 1f/sub 7/2/-neutron-orbit radius inferred from this data definitively demonstrates that the explanation of the Coulomb-energy anomaly cannot be found in a reduction of the valence-orbit radius.