Search

We report results on the ratio of midrapidity antiproton-to-proton yields in Au+Au collisions at sqrt[s(NN)] = 130 GeV per nucleon pair as measured by the STAR experiment at RHIC. Within the rapidity and transverse momentum range of /y/0.5 and 0.4p(t)1.0 GeV/c, the ratio is essentially independent of either transverse momentum or rapidity, with an average of 0.65+/-0.01((stat))+/-0.07((syst)) for minimum bias collisions. Within errors, no strong centrality dependence is observed. The results indicate that at this RHIC energy, although the p-p pair production becomes important at midrapidity, a significant excess of baryons over antibaryons is still present.

The AGS Experiment 896 was designed to study strangeness production in Au—Au collisions at 11.6A GeV/c, in particular the formation of a six-quark di-baryon the H0. Heavy ion collisions provide favorable conditions for the H0 formation either via coalescence of two Λ particles (owing to the large Λ production cross section) or direct production from the possible formation of a quark-gluon plasma. E896 also measured strange meson and baryon distributions from mid-rapidity. Preliminary results from this experiment are presented as well as details of the expected sensitivity for the H0 search.

The double differential multiplicities and rapidity distributions for Lambda hyperon production in central Au+Au interactions at AGS in the range of rapidities from 1.7 to 3.2 and the range of transverse kinetic energies from 0.0 to 0.7 GeV are parametrized in terms of the the Blast Wave approximation. The longitudinal and transverse radial expansion parameters and the mean temperature of Lambda hyperons after the freeze-out of the nuclear matter are presented. The predictions of the RQMD model with and without mean field potentials are compared to our data. Both variants of RQMD are parameterized in terms of the Blast Wave model and the results of such parameterizations are compared to the experimental ones. It is found that inclusion of the mean field potentials in RQMD is essential to account for the strong expansion observed in the data., 20 pages, LaTeX using elsart.sty, 10 encapsulated postscript figures

A progress report is given for the various components of the STAR detector system. We report on the recent developments in the detector proto-typing and construction, with an emphasis on the main TPC, recent TPC cosmic ray testing and shipping to Brookhaven National Laboratory

The analyzing power ${A}_{N}$ in inclusive ${\ensuremath{\pi}}^{\ensuremath{-}}$ and ${\ensuremath{\pi}}^{+}$ production has been measured with a 200 GeV/c transversely polarized antiproton beam over a wide ${x}_{F}$ range $(0.2\ensuremath{\le}{x}_{F}\ensuremath{\le}0.9)$ and at moderate ${p}_{T}$ $(0.2\ensuremath{\le}{p}_{T}\ensuremath{\le}1.5\mathrm{GeV}/\mathrm{c})$. The asymmetry ${A}_{N}$ increases with increasing ${x}_{F}$ from zero to large positive values for ${\ensuremath{\pi}}^{\ensuremath{-}}$'s, and decreases from zero to large negative values for ${\ensuremath{\pi}}^{+}$'s. A threshold for the onset of the asymmetry is observed about ${p}_{T}\ensuremath{\sim}0.5\mathrm{GeV}/\mathrm{c}$, below which ${A}_{N}$ is essentially zero and above which ${A}_{N}$ increases (decreases) with ${p}_{T}$ for ${\ensuremath{\pi}}^{\ensuremath{-}}$'s ( ${\ensuremath{\pi}}^{+}$'s) in the covered ${p}_{T}$ range.

We report a large enhancement of 1.7 in deuteron polarization up to values of 0.6 due to frequency modulation of the polarizing microwaves in a two liters polarized target using the method of dynamic nuclear polarization. This target was used during a deep inelastic polarized muon-deuteron scattering experiment at CERN. Measurements of the electron paramagnetic resonance absorption spectra show that frequency modulation gives rise to additional microwave absorption in the spectral wings. Although these results are not understood theoretically, they may provide a useful testing ground for the deeper understanding of dynamic nuclear polarization., 10 pages, including the figures coming in uuencoded compressed tar files in poltar.uu, which also brings cernart.sty and crna12.sty files needed

We have measured the spin-dependent structure function $g_1^p$ of the proton in deep inelastic scattering of polarized muons off polarized protons, in the kinematic range $0.003, Comment: 11 pages, CERN-PPE/94-57

The theme that unites the sometimes seemingly disparate experiments undertaken by the Bonner Lab Medium Energy Group is a determination to understand in detail the many facets and manifestations of the strong interaction, that which is now referred to as nonperturbative QCD. Whether we are investigating the question of just what does carry the spin of baryons, or the extent of the validity of the SU(6) wavefunctions for the excited hyperons (as will be measured in their radiative decays in our CEBAF experiment), or questions associated with the formation of a new state of matter predicted by QCD (the subject of our BNL experiments E810, E854, as well as our approved experiment at RHIC), -- all these projects share this common goal. Our other experiments represent different approaches to the same broad undertaking. LAMPF E1097 will provide definitive answers to the question of the spin dependence of the inelastic channel of pion production in the n-p interaction. FNAL E683 may well open a new field of investigation in nuclear physics: that of just how quarks and gluons interact with nuclear matter as they transverse nuclei of different sizes. In most all of the experiments mentioned above, the Bonner Lab Groupmore » is playing major leadership roles as well as doing a big fraction of the hard work that such experiments require. We use many of the facilities that are unavailable to the intermediate energy physics community and we use our expertise to design and fabricate the detectors and instrumentation that are required to perform the measurements which we decide to do.« less

Future experiments on RHIC and LHC require the performance of photodetectors with stable operation in strong magnetic fields, 0.5 T for the STAR (RHIC) Time of Flight system (TOF) and more than 3 T for the CMS (LHC) electromagnetic calorimeter. Such photodetectors have to possess a good energy and time resolution, for TOF measurements less than 100 ps [1] simultaneously being radiation hard up to some Mrad. Fine mesh dynode proximity photomultiplier tubes FMPMT developed and produced in recent years by Hamamatsu are the most promising detectors for the above specified goals. Different kinds of PMT were tested by some experimental groups in axial magnetic field up to 1.5 T [2–4]. The obtained PMT time resolution in beam test together with Bicron scintillator was better than 100 ps [1].

Kinematically complete data are presented from the 2 H(n, np)n reaction at 130 MeV The data, in the form of third differential cross sections, cover 40 pairs of final state angles and final state energies ranging from 1 to 100 MeV. The n-n and n-p final state interactions and n-p quasi-free scattering processes are observed in various regions of phase space over a wide range of kinematic conditions. The gross features of the data are reproduced by a simple model based on the simple impulse approximation and the Watson-Migdal model, and a value for the neutron-neutron scattering length, α an = −17.1 ± 0.8 fm, is extracted from one per of angles using this model. The fit to the quasi-free scattering data produced by the simple impulse approximation is unsatisfactory, however, and requires further investigation. No attempt has yet been made to apply more sophisticated three-body models to this higher energy data.

Pion energy spectra from the reactions $\mathrm{np}\ensuremath{\rightarrow}\mathrm{nn}{\ensuremath{\pi}}^{+}$ and $\mathrm{np}\ensuremath{\rightarrow}\mathrm{pp}{\ensuremath{\pi}}^{\ensuremath{-}}$ were measured as a function of the angle at 790 MeV. The angular distribution in the $\mathrm{np}$ center-of-momentum system was given by [$(123.1\ifmmode\pm\else\textpm\fi{}2.7)+(88.3\ifmmode\pm\else\textpm\fi{}4.9){{cos}^{2}\ensuremath{\theta}}^{*}$] \ensuremath{\mu}b/sr. The total cross section for each reaction was found to be 1.92\ifmmode\pm\else\textpm\fi{}0.20 mb. Evidence for $T=0$ pion production was observed in shape differences between the positive- and negative-pion spectra. However, it was shown that pions are preferentially produced by nucleons in a

The excitation function of the reaction p p→ Λ Λ in the threshold region has been measured at LEAR. Sixteen measurements of the total cross section, in the energy range between 0.85 MeV below threshold and 4.05 MeV above, are presented. The shapes of the measured differential cross sections indicate a remarkably strong p-wave contribution even down to the reaction threshold. We also report here the measurement of significant polarizations in the threshold region; these are compared with previous higher-energy data.

The reaction $$\bar pp \to \bar \Lambda \Lambda $$ is related to the creation of a strange-antistrange quark pair. It is studied at LEAR. Total and differential cross-sections, as well as $$\bar \Lambda $$ and Λ polarization and spin correlation data were obtained. First results on the reaction $$\bar p$$ p→KSKS in the energy range of the $$\bar \Lambda $$ Λ threshold can be shown. Future possibilities of the experiment are indicated.

The inclusive p-C analyzing power has been measured for laboratory scattering angles between 3° and 19° for energies between 80 and 584 MeV. The experiment was performed at LAMPF using a large solid angle polarimeter. These data have been incorporated into the existing data base to obtain a new energy dependent p-C analyzing power fit for the energy range 100–750 MeV.

We have measured the np (nd) elastic scattering cross sections at 25(17) angles in the interval 30°–168° (c.m.), using a neutron beam with a broad spectrum peaked near 130 MeV. At backward angles the outgoing charged particles from a liquid hydrogen (deuterium) target were detected; at forward angles we detected neutrons scattered from a hydrogenated (deuterated) scintillating target. Cross sections have been normalized to the energy dependent solution of the Livermore nucleon-nucleon partial wave analysis, evaluated at 130 MeV. The np measurements represent a marginal improvement on previous work; the nd cross sections show some differences from pd measurements, in agreement with earlier indications at an energy of 152 MeV.

The Wolfenstein polarization observables DNN, D SΩ and D LΩ , where Ω denotes a mixture of S and L polarization components, the induced polarization P, and the analysing power A have been measured for the reaction pp→ppπ0 at 800, 733, and 647 MeV. Comparisons are made to theoretical predictions of the model of Dubach, Kloet and Silbar.

The polarization transfer parameters,KNN and KLL, have been measured in p d→ n X and p 9Be→ n X at 0° and 800 MeV. The quasifree p d→ n X values for KNN and KLL are close to the free n-p measured values. The rather large values of KLL demonstrate that this transfer mechanism will provide a useful source of polarized neutrons at medium energies.

The inclusive reaction $\mathrm{np}\ensuremath{\rightarrow}\mathrm{pX}$, where $X$ includes a pion, has been studied at 795 MeV with measurements of the cross section $\frac{{d}^{2}\ensuremath{\sigma}}{\mathrm{dp}d\ensuremath{\Omega}}$. Proton momentum spectra were measured for laboratory angles between 0\ifmmode^\circ\else\textdegree\fi{} and 31\ifmmode^\circ\else\textdegree\fi{}. These angles cover the full forward hemisphere in the center-of-mass system and give, with the use of symmetry assumptions, a value for the total reaction cross section, ${\ensuremath{\sigma}}^{R}=11.0\ifmmode\pm\else\textpm\fi{}0.8$ mb, exclusive of the $\mathrm{np}\ensuremath{\rightarrow}d{\ensuremath{\pi}}^{0}$ reaction. The data are also presented as measurements of the cross section $\frac{{d}^{2}\ensuremath{\sigma}}{\mathrm{dt}\mathrm{dM}}$, where $t$ is the four-momentum transfer squared and $M$ is the invariant missing mass. The results are compared with a model calculation of one-pion exchange that includes $\ensuremath{\rho}$ and $\ensuremath{\omega}$ exchange. The $t$ dependence is also discussed in terms of a statistical model.

The differential cross section for n--p elastic scattering in the angular region 145$sup 0$ < theta/sub c.m/ < 180$sup 0$ has been measured with high statistical accuracy using the monoenergetic neutron beam at Clinton P. Anderson Meson Physics Facility. The results differ significantly from previous Dubna and Princeton-Pennsylvania Accelerator results but agree reasonably well with recent Saclay data except at extreme backward angles. (AIP)

The measured 7 Li(p,n), and 6 Li(n,p) cross sections at 0° show a high-energy peak (≈25 MeV/ c FWHM) which we attribute primarily to nuclear charge exchange leading to final states in 7 Be, 6 Be, and 6 He, respectively. By contrast, the 7 Li(n,p) cross section at O° shows a broad weak high-energy peak believed due mostly to break-up processes. At 16°, the 6,7 Li(n,p) cross sections are dominated by quasi-elastic scattering.

A description is given of a TPC system that operates in a relativistic heavy-ion beam and yields good track reconstruction efficiency in very-high-multiplicity events. The mechanical construction of the chamber is discussed. A set of custom hybrid circuits are used to build a very compact, cost-effective electronics system mounted directly on the chamber. Results from running in test beams and from preliminary experimental runs are given.

The differential cross section for n-p elastic scattering at 801.9 MeV has been measured with high statistical precision and good relative accuracy over the angular range $60\ifmmode^\circ\else\textdegree\fi{}l{\ensuremath{\theta}}^{*}l180\ifmmode^\circ\else\textdegree\fi{}$. The absolute normalization is based on the simultaneously observed yield of deuterons from the $\mathrm{np}\ensuremath{\rightarrow}\mathrm{d}{\ensuremath{\pi}}^{0}$ reaction and is good to 7%. A nearly monoenergetic neutron beam, produced by proton bombardment of a liquid-deuterium target, was directed through a liquid-hydrogen target. The angle, velocity, and momentum of charged particles ejected from the target were measured in a magnetic spectrometer equipped with multiwire proportional chambers and timing scintillators. The results are in good agreement with earlier Saclay and LAMPF data and include an angular region not covered before. The pole-extrapolation method of Chew was used to extract a value ${f}^{2}=0.075\ifmmode\pm\else\textpm\fi{}0.005$ for the pion-nucleon coupling constant which is in agreement with accepted values, thus providing evidence for the accuracy of the shape and normalization of the angular distribution.

The neutron-proton differential cross section has been measured at 25.8 and 50 MeV to a precision of approx. =2% for backward hemisphere c.m. angles and approx. =3% for forward angles. Relative cross sections are presented for a c.m. angular range from 20/sup 0/ to near 180/sup 0/. The 25.8 MeV data are in good agreement with previous measurements at 24.0 and 27.2 MeV. The 50 MeV data are not in agreement with previous measuremements, and as has been noted before it is believed that these previous data are in error.

We have measured the double differential cross section for bremsstrahlung production in neutron-proton collisions near 130 MeV. Outgoing nucleons were detected at eight pairs of angles simultaneously. The cross sections agree with several theoretical predictions for those four angle pairs in which the proton emerged at 20° ( θ = 20°), but are larger than expected in the four cases that θ p = 32°. The method of data reduction, and the sources of uncertainty, are discussed in detail.

The analyzing power A, and spin transfer parameters K/sub N/N, K/sub S/S, K/sub S/L, and K/sub L/L have been measured in the np charge-exchange (np..-->..pn) region at 790 MeV. These data provide new and unique information on the spin dependence of the np interaction in the charge-exchange region. Models which explain the charge-exchange peak in the np elastic differential cross section as being due to interference between one-pion exchange and a slowly varying background are in basic agreement with the data.

The angular distributions of deuterons for 7/sup 0/ < or = theta/sub c.m./ < or = 60/sup 0/ have been measured for 56.3 MeV neutrons incident on targets of /sup 6/Li and /sup 7/Li. Transitions corresponding to the pickup of 1p-shell and 1s-shell protons are strong with the latter exhibiting structure indicative of groups of excited states in /sup 5/He and /sup 6/He. In /sup 5/He these have excitation energies of 16.7, 18.5, and 20.5 MeV, and in /sup 6/He an average excitation energy of 15.6 MeV. The spectroscopic factors deduced from the measurements are in good agreement with theoretical values where the latter are available.

The depolarization parameter D NN for pp elastic scattering at θ cm = 90 ° has been measured at twelve momenta between 0.9 and 1.5 GeV/ c . The moduli of the three transversity amplitudes T 1 , T 3 , and T 4 have been extracted from these data and from previous measurements of the differential cross section and spin correlation parameter A NN (90 °). Smooth energy dependence is found for all three amplitude moduli.

The 0\ifmmode^\circ\else\textdegree\fi{} neutron spectra resulting from 800 MeV proton bombardment of targets of Al, Ti, Cu, W, Pb, and U have been measured for neutron momenta above 500 MeV/c. Integrated cross sections for the quasielastic charge exchange peaks and the broad pion associated peaks at lower momenta show a remarkably smooth dependence on atomic mass of the target, varying as ${A}^{\frac{2}{3}}$ and ${A}^{\frac{1}{2}}$, respectively.

A carbon polarimeter has been built and used for protons with energies between 100 and 800 MeV. The polarimeter accepts scatters in the carbon analyzer up to 30° lab , with negligible instrumental asymmetries. Drift chambers 60 cm square were used with a system for resolving the left-right ambiguity inherent in drift chambers. A hardware system for rejecting small angle scatters is described. The polarimeter is routinely used to measure spin transfer parameters with a typical precision of ±0.03 in about eight hours of low-duty LAMPF beam.

800 MeV elastic p+p spin-depolarization and -rotation parameters D/sub N/N, D/sub S/S, D/sub L/L, D/sub S/L, and D/sub L/S have been measured for the center-of-momentum angular range 4.8/sup 0/--23.8/sup 0/ (0.26 fm/sup -1/< or =q< or =1.28 fm/sup -1/). Statistical uncertainties are approx. = +- 0.01--0.02 and total systematic uncertainty is < or = +- 0.035. The data are in overall agreement with predictions from global phase shift analysis.

Deuteron "missing mass' spectra have been measured at 1.46 GeV/c over the complete allowed phase space angular region for the np→d(ππ)0 reaction. Strong enhancements, evidence for the Abashian-Booth-Crowe effect, are not observed near momenta corresponding to the two pion missing mass values. A total cross section of 28.5±1.5 μb has been determined for this reaction. NUCLEAR REACTIONS np→d(ππ)0; E=795 MeV; measured σ(Pd,θ); deduced σ.

The spin-transfer parameters KNN and KLL have been measured for at 0° and 800 MeV for neutron momenta between 700 and 1200 MeV c . Peak values of KNN and KLL are −0.30 ± 0.05 and −0.5 ± 0.1 respectively. These results are in substantial disagreement with VerWest's field theoretic model.

The spin depolarization parameters ${D}_{\mathrm{NN}}$, ${D}_{\mathrm{SS}}$, ${D}_{\mathrm{LS}}$, and the spin transfer parameters ${K}_{\mathrm{NN}}$, ${K}_{\mathrm{SS}}$, ${K}_{\mathrm{LS}}$ have been measured for $\mathrm{pp}\ensuremath{\rightarrow}\mathrm{pp}$ at 800 MeV. Angular range is 21 to 90\ifmmode^\circ\else\textdegree\fi{} c.m. for the $D$ parameters, and 46 to 90\ifmmode^\circ\else\textdegree\fi{} c.m. for the $K$ parameters. Typical uncertainties are about \ifmmode\pm\else\textpm\fi{}0.025. These data, when combined with previous data make possible a complete isovector phase shift and amplitude analysis at 800 MeV.

The Brookhaven Alternating Gradient Synchrotron polarized proton beam incident on a beryllium target was used for inclusive ..lambda.. production at beam momenta of 13.3 and 18.5 GeV/c. The beam polarization was transverse to the beam direction with magnitude 0.63 at 13.3 GeV/c and 0.40 at 18.5 GeV/c. The ..lambda.. polarization was measured and found to be in agreement with results from earlier experiments which used unpolarized proton beams. Analyzing power A/sub N/ and spin transfer D/sub N//sub N/ of the ..lambda..'s were both measured and compared with a hyperon-polarization model in which the polarization arises from a Thomas-precession effect. There is good agreement with its predictions: A/sub N/ = 0 and D/sub N//sub N/ = 0. In particular, our measurement of = -0.009 +- 0.015 supports the idea that the valence quarks carry all of the hadron spin, since this assumption is implicit in the model's use of SU(6) wave functions to form final-state hadrons from beam fragments and sea quarks. The presence of substantial K/sub S/ samples at both beam momenta and Lambda-bar's at 18.5 GeV/c prompted a measurement of their analyzing powers, which yielded A/sub N/(K/sub S/) = -0.094 +- 0.012 at 13.3 GeV/c beam momentum and -0.076more » +- 0.015 at 18.5 GeV/c, and A/sub N/(Lambda-bar) = 0.03 +- 0.10.« less

A collimated beam of 50 MeV neutrons with a polarization of 0.46±0.02 and a flux of ∼104n/cm2s at 3 m is produced via the T(d,n)4He reaction. Beams up to 20 μA of 38 MeV deuterons are directed through a liquid nitrogen cooled, pressurized (5.5 atm) tritium target. Details of the design, construction, and operation of the neutron facility are presented. The procedures for transferring the tritium to and from the target are also discussed as well as several safety features.

The polarization in neutron-proton scattering at 29.6 MeV was deduced from asymmetries measured at every 10 degree c.m. from 50 to 150 degree c.m. The incident neutron beam was derived from a high-pressure deuterium gas cell via the $sup 2$H(d, n)$sup 3$He reaction at 37 degree c.m. The beam passed through a spin rotation magnet and, at the target location 5.4 m from the gas cell, possessed a flux of 5 times 10$sup 5$ n/sec and a polarization of 0.32 plus-or- minus 0.04. Data between 50 and 110 degree c.m. were obtained using scintillating CH target in coincidence with neutron detectors, while data between 120 and 150 degree c.m. were obtained using recoil protons from a CH$sub 2$ target. Total errors in the derived polarizations ranged from plus-or-minus 0.007 to plus-or-minus 0.022. These data agree very well with three previous values measured near 30 MeV at Los Alamos, but they disagree with Harwell data indicating small or negative polarizations near 150 degree c.m. The present results agree well with predictions of the Livermore X and Yale IV phase shift sets, but slightly favor the former. (AIP)

A device, dubbed QPAN, for determining the polarization of an intermediate energy neutron beam has been developed. QPAN consists of a double arm scintillator range telescope viewing a CH2 target. The effective analyzing power was measured to be 0.18 ± 0.01.

The principal detector for AGS Experiment 810 is a Time Projection Chamber (TPC) in which it is intended to measure momenta and angles of a major fraction of the charged particles from each light ion collision. This report describes the results of a test of a prototype of the TPC in a beam of (14.6 × 16 = 233.6 GeV c ) oxygen ions run in June of this year.

The inclusive p-C analyzing power has been measured for laboratory scattering angles between 4° and 25°, for energies between 100 and 750 MeV. The inclusive p-Be analyzing power has been measured at 780 MeV between 4° and 28°. The experiment was performed at LAMPF using a large solid angle polarimeter. An energy dependent empirical fit to these data as well as to data from SIN and TRIUMF is presented. The data from all three facilities are in generally good agreement.

The deuteron spectra from (n,d) reactions at 800 MeV near 0/sup 0/ are characterized by a high energy quasielastic scattering peak, and at lower momentum, a quasifree scattering peak. The ratio of the quasifree to quasielastic cross sections is approximately 10 : 1. Both cross sections exhibit an A/sup 1/3/ mass dependence over the range of target nuclei studied. Comparisons are made with corresponding proton-induced quasielastic and quasifree deuteron production.

The cross section for elastic scattering of 794-MeV neutrons by deuterium has been measured for neutron center of mass angles from 139\ifmmode^\circ\else\textdegree\fi{} to 179\ifmmode^\circ\else\textdegree\fi{}. The angular distribution is fitted very well both by an empirical function $\ensuremath{\alpha}{e}^{\ensuremath{\beta}(\ensuremath{\mu}\ensuremath{-}{\ensuremath{\mu}}_{{180}^{\ensuremath{\circ}}})}$ and by a calculation that uses the one parameter Craigie-Wilkin triangle diagram technique.[NUCLEAR REACTION $n^{2}\mathrm{H}\ensuremath{\rightarrow}^{2}\mathrm{H}n$, $E=794$ MeV; measured $\ensuremath{\sigma}(\ensuremath{\theta})$. Calculated $\ensuremath{\sigma}(\ensuremath{\theta})$ with triangle diagram techniques.]

The p—d spectra show sharp high-energy peaks (≈ 15 MeV FWHM) with integrated yields of 30 and 31 mb/sr, respectively and with lower-energy bumps associated with pion production. The p—p spectra reflect the influence of the Δ(1232) resonance.

A measurement has been made of the neutron polarization, $P$, from 800-MeV $p\ensuremath{-}n$ quasielastic scattering at 133\ifmmode^\circ\else\textdegree\fi{} c.m. This together with previous measurements of the analyzing power, $A$, at the same angle in free $n\ensuremath{-}p$ scattering at 775 MeV constitutes a $P\ensuremath{-}A$ check of time-reversal invariance. No evidence is found for time-reversal invariance violation in $n\ensuremath{-}p$ scattering at medium energies, a clear-cut disagreement with the model predictions of Bryan and Gersten.

The analyzing power ${A}_{N}$ in inclusive ${\ensuremath{\pi}}^{0}$ production has been measured with use of the new 185-GeV/c Fermilab polarized proton beam. We obtain the value ${A}_{N}=0.10\ifmmode\pm\else\textpm\fi{}0.03$ for ${\ensuremath{\pi}}^{0}'s$ in the kinematic region $0.2l{x}_{F}l0.8$ and $0.3l{p}_{T}l1.2$ GeV/c. In certain models of particle production this suggests that the spin of the proton is carried by its valence quarks.

The proton spectrum resulting from 794-MeV neutron bombardment of deuterium was measured at several angles. The angular distribution of the integral of the quasielastic charge exchange peak is fitted very well by the two exponential form dt/dt = ..cap alpha../sub 1/e/sup ..beta..//sup t/ + ..cap alpha../sub 2/e/sup beta2t/ as has previously been found for the np elastic case. The ratio of the two cross sections at t = 0 is 0.56 +- 0.04. A modified impulse approximation calculation accounts for most features of the observed angular distribution.

Using a liquid deuterium target, 800 MeV quasielastic $\stackrel{\ensuremath{\rightarrow}}{p}+n$ and $\stackrel{\ensuremath{\rightarrow}}{p}+p$ analyzing powers were measured over the center-of-momentum angular range 14\ifmmode^\circ\else\textdegree\fi{}-75\ifmmode^\circ\else\textdegree\fi{}. Elastic $\stackrel{\ensuremath{\rightarrow}}{p}+p$ analyzing powers were measured over the center-of-momentum angular range 10\ifmmode^\circ\else\textdegree\fi{}-47\ifmmode^\circ\else\textdegree\fi{} using a liquid hydrogen target, and elastic $p+p$ differential cross sections were obtained over the angular range 6\ifmmode^\circ\else\textdegree\fi{}-90\ifmmode^\circ\else\textdegree\fi{} using CH and C${\mathrm{H}}_{2}$ targets. The quasielastic $\stackrel{\ensuremath{\rightarrow}}{p}+p$ data are in good agreement with existing elastic $\stackrel{\ensuremath{\rightarrow}}{p}+p$ data, suggesting that the effects of final state interactions and Fermi motion averaging are small at this energy for the range of momentum transfer covered by these data. Results of phase shift analyses are reported, and the amplitudes important to microscopic analysis of 800 MeV $\stackrel{\ensuremath{\rightarrow}}{p}$+nucleus elastic differential cross section and analyzing power data are discussed. Use of these amplitudes to generate the microscopic Kerman-McManus-Thaler optical potential for 800 MeV $\stackrel{\ensuremath{\rightarrow}}{p}$+$^{40}\mathrm{Ca}$ elastic scattering does not resolve the problems encountered previously concerning nuclear size information and poor fits to the analyzing power data.NUCLEAR REACTIONS $^{2}\mathrm{H}(\stackrel{\ensuremath{\rightarrow}}{p}, pn)p$, $^{2}\mathrm{H}(\stackrel{\ensuremath{\rightarrow}}{p}, pp)n$, $^{1}\mathrm{H}(\stackrel{\ensuremath{\rightarrow}}{p}, p)$, $^{1}\mathrm{H}(p, p)$; ${E}_{p,\mathrm{inc}}=800$ MeV; measured $p+p$ elastic $\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}}$ for $6\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\le}{\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}\ensuremath{\le}90\ifmmode^\circ\else\textdegree\fi{}$; measured $\stackrel{\ensuremath{\rightarrow}}{p}+p$ elastic ${A}_{y}(\ensuremath{\theta})$ for $10\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\le}{\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}}\ensuremath{\le}47\ifmmode^\circ\else\textdegree\fi{}$; measured $\stackrel{\ensuremath{\rightarrow}}{p}+p$ and $\stackrel{\ensuremath{\rightarrow}}{p}+n$ quasielastic ${A}_{y}(\ensuremath{\theta})$ for $14\ifmmode^\circ\else\textdegree\fi{}\ensuremath{\le}{\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}\ensuremath{\le}75\ifmmode^\circ\else\textdegree\fi{}$; CH, C${\mathrm{H}}_{2}$, liquid hydrogen and liquid deuterium targets; two arm coincidence for quasielastic; phase shift analyses; microscopic (KMT) optical model calculations for 800 MeV $\stackrel{\ensuremath{\rightarrow}}{p}$+$^{40}\mathrm{Ca}$.