J. Clement

Measurement of the transverse spin dependence of the pp total cross section in the 1–3 GeV/c region☆

Abstract The pp total cross section difference between pure transverse spin states was measured in the laboratory momentum range 1–3 GeV/ c . Significant differences were found and these differences show striking energy dependence. This structure is in disagreement with the predictions of simple exchange models.

Measurement of the spin parameters A and Ann in pp elastic scattering in the 1–3 GeV/c region☆

Abstract We have measured the asymmetry parameter A and the spin correlation parameter A nn in pp elastic scattering, using the Argonne ZGS polarized proton beam and a polarized proton target. Angular distributions of A and A nn for | t | ≳ 0.2 (GeV/ c ) 2 were obtained at eight momenta between 1.10 and 2 if 2.75 GeV/ c . We find significant structure in both the energy and t -dependence of A nn at these energies. At p lab ≈ 1.34 GeV/ c A nn reaches a very large value of about 0.8–0.9 near θ cm = 90°.

Modular TPCs for relativistic heavy-ion experiments☆

Abstract 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.

Reaction mechanisms and isospin effects for the π±+D→p+π±+n processes at Pπ=340 MeV/c

Abstract The first kinematically complete counter measurements of the D( π ± , pπ ± )n reactions in the Δ(1232) region are reported. Calculations based on low order diagrams compare well with the data. The ratio pπ + /pπ − depends strongly on the spectator particle momentum, and its behavior is qualitatively reproduced.

A search for narrow states in antineutron-proton total and annihilation cross sections near N̄N threshold

Abstract The np total and annihilation cross section have been measured from near NN threshold (1880 MeV) to 1940 MeV with RMS resolution ranging from 0.08 MeV (1880 MeV) to 6.7 MeV (1940 MeV). No significant narrow meson structures were seen, with 90% CL upper limits of 40–180 mb-MeV on σΓ for states with width less than our resolution. Combined with increasing unitarity bounds on σ as one approaches threshold, these limits confine widths of possible predicted states below 1900 MeV to less than ∼ 1 MeV.