[en] Forward-angle pion inelastic scattering was measured for ¹²C, ²⁸Si, and ⁴⁰Ca to search for the predicted (but previously unobserved) spin-flip dipole state in these nuclei. Pion inelastic scattering angular distributions at T/sub pi/ = 164 MeV were also measured for the isoscalar, natural-parity states of ¹⁶O and low-lying monopole states in ¹²C and ²⁸Si to test the distorted-wave impulse approximation (DWIA) model of pion inelastic scattering. Existing structure information for these states enabled this quantitative test of the DWIA model. Generally, good agreement was found between these calculations and the data. Large discrepancies were observed, though, for the ¹⁶O(1₁^-. 1₁⁴, 0₃⁺) states and the forward-angle cross sections for the ¹²C(0₂⁺) state. These discrepancies demonstrate the need for the contribution of higher-order processes to pion scattering. The forward-angle measurements on ¹²C and ²⁸Si revealed the existence of forward-peaking angular distributions for states in the giant resonance region of these nuclei. Comparisons with DWIA calculations employing a transition density for a state exhausting the spin-flip dipole transition strength from the ground state indicate the present results have located a significant fraction of the expected strength. The present measurements are not sufficient to exclude the possibility that the observed forward-peaked enhancements are fragments of the giant monopole resonance. The observed strengths are inconsistent with extensive measurements performed with other probes if this were the correct interpretation. This indicates that a large fraction of the expected isoscalar, spin-flip dipole strength is concentrated in states which lie lower in excitation energy than the giant dipole resonance

[en] Forward-angle pion inelastic scattering was measured for ¹²C, ²⁸Si, and ⁴⁰Ca to search for the predicted (but previously unobserved) spin-flip dipole state in these nuclei. Earlier theoretical models suggested that pion inelastic scattering angular distributions would peak at zero degrees for these transitions unlike those for non-spin-flip dipole states. Pion inelastic scattering angular distributions at T/sub π/ = 164 MeV were also measured for the isoscalar, natural-parity states of ¹⁶O and low-lying monopole states in ¹²C and ²⁸Si to test the distorted-wave impulse approximation (DWIA) model of pion inelastic scattering. Existing structure information for these sites enable this quantitative test of the DWIA model. Generally, good agreement was found between these calculations and the data. Large discrepancies were observed, through, for the ¹⁶O(1₁^-, 4₁⁺, O₃⁺) states and the forward-angle cross sections for the ¹²C(O₂⁺) state. These discrepancies demonstrate the need for the contribution of higher order processes to pion scattering

[en] The transition regime in the strong interactions spans energies from where a purely baryon and meson description is appropriate to where a perturbative description in terms of quarks and gluons emerges. The study of the interface between perturbative and non-perturbative QCD is active even at very high-energy facilities

[en] Experimental systematics of ΔJ=0,ΔT not equal to 0 exclusive, pion-induced double-charge-exchange (DCX) transitions have been found to have regular features which differ dramatically from those observed for double-isobaric-analog double charge exchange (DIAT-DCX). Observables of non-analog DCX transitions include rapidly varying excitation functions resulting in a peak near T/sub/π=160 MeV of width GAMMA = 75 MeV, angular distributions which are consistent with diffractive scattering, and a mass dependence of the forward-angle cross section varies as A/sup -4/3/. These features have not, to date, been successfully understood within models of the pion-nucleus interaction. The regular features of the data argues for a simpler theoretical explanation for non-analog DCX than required for DIAT-DCX

[en] A high energy resolution (σ≤ 1 MeV) neutron detector has been constructed and tested for neutrons in the energy range 80 MeV to 125 MeV. The detector was designed for exclusive, n-p coincidence, quasifree scattering experiments. The design eliminates the need for long neutron flight paths necessary for comparable energy resolution time of flight (TOF) measurements. Unlike TOF measurements, this design allows for a relatively compact geometry (<3 m flight path) with a comparable efficiency solid angle product. The detector consists of thin organic scintillators in which the neutron elastically scatters from free protons. The scattered protons are tracked by alternating thin X and Y horizontal drift chambers and detected in an array of NaI. Results from a test run will be discussed along with possible extensions of this design for use as a polarimeter

[en] Pion double-charge-exchange (DCX) reactions have provided many surprises from experimental studies performed at LAMPF. Features of the present data set may indicate that DCX proceeds by excitation of Δ₃₃ components in nuclear wave functions. The larger resonance-energy pion fluxes expected from LAMPF II will enable more complete experimental studies, which will yield further insight into the DCX reaction mechanism

[en] σ, A_y, P, and D_nn' measurements of inelastic proton scattering from ⁴⁰Ca in the region of quasi-free scattering (QFS) have been completed. Data for both the inclusive (p,p') and the exclusive (p,2p) reactions were taken concurrently utilizing the K600 spectrometer and focal plane polarimeter at θ_lab=30 degrees in coincidence with a large solid angle NaI detector array. This configuration permitted ∼50% coverage of the associated particle cone expected for QFS in the (p,2p) reaction. A comparison of the inclusive (p,p') observables to various models as well as to the preliminary angle-integrated exclusive results will be presented

[en] The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been developing the capability of accelerating, storing and colliding high-energy polarized proton beams over the past several years. During this development phase, important first measurements of cross sections and spin asymmetries for neutral pions produced in polarized proton collisions at √(s)=200 GeV have been completed by STAR and PHENIX, the two large collider experiments at RHIC. This contribution reports on progress of the RHIC spin program and provides an outlook for the future

[en] The physics goals that will be addressed by colliding polarized protons at the Relativistic Heavy Ion Collider (RHIC) are described. The RHIC spin program provides a new generation of experiments that will unfold the quark, anti-quark and gluon contributions to the proton's spin. In addition to these longer term goals, this paper describes what was learned from the first polarized proton collisions at √(s)=200 GeV. These collisions took place in a five-week run during the second year of RHIC operation

[en] LISS is a Light-Ion Spin Synchrotron and storage ring that is being considered as an upgrade of the Indiana University Cyclotron Facility. Current plans call for a racetrack design for the ring that will provide variable energy polarized proton and deuteron beams up to a momentum of 16 GeV/c and unpolarized light ions with 3 ≤A ≤ 40 accelerated to comparable rigidities. Experiments would be conducted using both polarized and unpolarized internal targets. The racetrack design for the ring will provide for two ∼100-m long, zero-dispersion straight sections that allow for the installation of sophisticated experimental equipment. The ring design will incorporate the recently developed technologies of Siberian snakes allowing for relatively straightforward acceleration and use of polarized beams for high-precision experiments, electron cooling for shrinking the emittance of the stored beams, and carrier-free polarized internal targets. This talk will focus on that part of the physics Program of the LISS facility associated with the production of strange and charmed quarks. Examples will include the study of the spin-dependence of the A-nucleon scattering length; second-generation associated hyperon production experiments emphasizing polarization transfer and exclusive identification of the produced hyperons (ΛΣ, etc.) with the goal of understanding the dynamical origin of hyperon polarization; and studies of the total charm production cross section in p-p collisions near threshold