Measurements of the spin asymmetry AN for the inclusive reactions (p) over right arrowC --> pi (+/-) X, pX and (p) over right arrowp --> pi (+/-) X are presented. Comparisons of hydrogen and carbon target results, and of data at 21.6 GeV/c and 200 GeV/c are given.

We report on a measurement of the neutron detection efficiency in NaI crystals in the Crystal Ball (CB) detector obtained from a study of π−p→π°n reactions at the Brookhaven National Laboratory AGS. A companion GEANT-based Monte Carlo study has been done to simulate these reactions in the CB, and a comparison with the data is provided.

Measurements at 19 beam kinetic energies between 1795 and 2235 MeV are reported fur the pp elastic scattering spin correlation parameter A(00nn)=A(NN)=C-NN. The c.m. angular range is typically 60-100 degrees. The measurements were performed at Saturne II with a vertically polarized beam and target (transverse to the beam direction and scattering plane), a magnetic spectrometer and a recoil detector, both instrumented with multi-wire proportional chambers, and beam polarimeters. These results are compared to previous data from Saturne II and elsewhere.

High quality analyzing powers for the {Pi}{sup -}p{yields}{yields}{Pi}{sup 0}n reaction have been obtained with a polarized proton target over a broad angular range at incident kinetic energies of 98.1, 138.8, 165.9, and 214.4 MeV. This experiment nearly doubled the existing {Pi}N single-charge-exchange database for energies ranging from 10 to 230 MeV, with 36 new analyzing powers. The Neutral Meson Spectrometer was used to detect the outgoing neutral pions. The data are well described by recent phase-shift analyses. When combined with high-precision and accurate cross section data at the same energies, the data can provide a good test of the degree of isospin breaking in the region of the {Delta}(1232) resonance. They will also be helpful for constraining the evaluation of the pion-nucleon {sigma} term from the scattering amplitudes.

Measurements at 18 beam kinetic energies between 1975 and 2795 MeV and at 795 MeV are reported for the pp elastic-scattering single spin parameter A(ooon)=A(oono)=A(N)=P. The c.m. angular range is typically 60-100 degrees. These results are compared to previous data from Saturne II and other accelerators. A search for energy-dependent structure at fixed c.m. angles is performed, but no rapid changes are observed. [S0556-2813(99)03710-3].

High quality analyzing powers for the ${\ensuremath{\pi}}^{\ensuremath{-}}\stackrel{\ensuremath{\rightarrow}}{p}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}n$ reaction have been obtained with a polarized proton target over a broad angular range at incident kinetic energies of 98.1, 138.8, 165.9, and 214.4 MeV. This experiment nearly doubled the existing $\ensuremath{\pi}N$ single-charge-exchange database for energies ranging from 10 to 230 MeV, with 36 new analyzing powers. The Neutral Meson Spectrometer was used to detect the outgoing neutral pions. The data are well described by recent phase-shift analyses. When combined with high-precision and accurate cross section data at the same energies, the data can provide a good test of the degree of isospin breaking in the region of the $\ensuremath{\Delta}(1232)$ resonance. They will also be helpful for constraining the evaluation of the pion-nucleon $\ensuremath{\sigma}$ term from the scattering amplitudes.

The analyzing power, A(N), in inclusive charged-pion production has been measured using a similar to 22-GeV/c transversely polarized proton beam on a carbon target. A large A(N) was found for x(F) > 0.5 and for 0.6 < p(T) < 1.2 GeV/c, with similar magnitudes and opposite sign for pi(+) and pi(-). This mirror behavior and the magnitudes are similar to pi(+/-) production from 200-GeV/c polarized protons on a hydrogen target. The analyzing power for inclusive proton production has also been measured and is consistent with zero. (C) 1999 Published by Elsevier Science B.V. All rights reserved.

High quality analyzing powers for the ${\ensuremath{\pi}}^{\ensuremath{-}}\stackrel{\ensuremath{\rightarrow}}{p}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}n$ reaction have been obtained with a polarized proton target over a broad angular range at incident kinetic energies of 98.1, 138.8, 165.9, and 214.4 MeV. This experiment nearly doubled the existing $\ensuremath{\pi}N$ single-charge-exchange database for energies ranging from 10 to 230 MeV, with 36 new analyzing powers. The Neutral Meson Spectrometer was used to detect the outgoing neutral pions. The data are well described by recent phase-shift analyses. When combined with high-precision and accurate cross section data at the same energies, the data can provide a good test of the degree of isospin breaking in the region of the $\ensuremath{\Delta}(1232)$ resonance. They will also be helpful for constraining the evaluation of the pion-nucleon $\ensuremath{\sigma}$ term from the scattering amplitudes.

High quality analyzing powers for the pi(-) (p) over right arrow --> pi(0)n reaction have been obtained with a polarized proton target over a broad angular range at incident kinetic energies of 98.1, 138.8, 165.9, and 214.4 MeV. This experiment nearly doubled the existing pi N single-charge-exchange database for energies ranging from 10 to 230 MeV, with 36 new analyzing Powers. The Neutral Meson Spectrometer was used to detect the outgoing neutral pions. The data are well described by recent phase-shift analyses. When combined with high-precision and accurate cross section data at the same energies, the data can provide a good test of the degree of isospin breaking in the region of the Delta(1232) resonance. They will also be helpful for constraining the evaluation of the pion-nucleon sigma term from the scattering amplitudes. [3S0556-2813(99)02408-5].

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 highest-energy measurement of Delta sigma(L)(pp) and the first ever measurement of Delta sigma(L)((p) over bar p), the differences between proton-proton and antiproton-proton total cross sections for pure longitudinal spin states, are described. Data were taken using 200-GeV/c polarized beams incident on a polarized-proton target. The results are measured to be Delta sigma(L)(pp) = -42 +/- 48(stat) +/- 53(syst) mu b and Delta sigma(L)((p) over bar p) = -256 +/- 124(stat) +/- 109(syst) mu b. Many tests of systematic effects were investigated and are described, and a comparison to theoretical predictions is also given. Measurements of parity nonconservation at 200 GeV/c in proton scattering and the first ever of antiproton scattering have also been derived from these data. The values are consistent with zero at the 10(-5) level.

A movable polarized proton target is planned to be installed in polarized beams of the Synchrophasotron-Nuclotron complex in order to carry out a spin physics experimental program at Dubna. The project is described and the first proposed experiments are discussed.

An overview of the STAR experiment at the Relativistic Heavy Ion Collider is presented. The experiment will concentrate on the measurement of particle production and jet production at midrapidity in a search for the Quark-Gluon Plasma. These hadronic observables will be studied on an event-by-event basis to determine the thermodynamics of single events and to identify special and unusual events. The physics addressed by STAR is discussed.

The invariant double-differential cross section, E1E2d6σ / dp31dp32, and the double-spin asymmetry, A LL, for inclusive multi-γ pair production in which γ-rays came from neutral mesons were measured with a 200 GeV/c longitudinally-polarized proton beam and a longitudinally-polarized proton target. Most of the multi-γ pairs comes from two-jet type events which are sensitive to partonic interaction. The ALL values were found to be consistent with zero. The invariant double-differential cross section for inclusive π0π0 production was also measured. These measured cross sections are consistent with LUND Monte Carlo simulations. Using the LUND Monte Carlo simulation package with the Carlitz-Kaur model of spin dependent distribution functions of valence quarks, the ALL values have been compared with theoretical predictions of gluon polarization, ΔG/G. The results put restrictions on the size of ΔG/G in the region of 0.05 ⪅ x ⪅ 0.35.

The angular dependece of the pp elastic scattering spin correlation parameter was measured in the angular range from 60° to 97° CM at 14 energies between 1.96 and 2.23 GeV. A rapid decrease of the energy dependence of this observable at 90° CM is observed around 2.11 GeV kinetic energy. This agrees with the behavior of Aoonn predicted on the basis of an exotic six-quark structure. The Aoonn (90° CM), together with the known differential cross section, allows the determination of the absolute value of the pure spin-singlet amplitude. The energy dependence of this amplitude shows a shoulder centered at 2.11 GeV, corresponding to a total mass of 2.735 GeV and an estimated width of 17 MeV.

The present article describes an apparatus used for the measurement of spin dependent observables at SATURNE II. Observables for np elastic and quasi-elastic scattering were measured between 0.31 and 1.1 GeV, those for pp elastic scattering between 1.94 and 2.24 GeV. Measurements of pn and pp observables with an unpolarized 6LiD and 7LiH targets around 2 GeV were also carried out. Fast electronics, on-line data acquisition, event selection and off-line analysis are presented.