281 research outputs found
Longitudinal Momentum Fraction X_L for Two High P_t Protons in pp->ppX Reaction
We present an analysis of new data from Experiment E850 at BNL. We have
characterized the inclusive cross section near the endpoint for pp exclusive
scattering in Hydrogen and in Carbon with incident beam energy of 6 GeV. We
select events with a pair of back-to-back hadrons at large transverse momentum.
These cross sections are parameterized with a form
, where is the ratio of the longitudinal momentum
of the observed pair to the total incident beam momentum. Small value of
may suggest that the number of partons participating in the reaction is large
and reaction has a strong dependence on the center-of-mass energy. We also
discuss nuclear effects observed in our kinematic region.Comment: 4 pages, 2 figures, to be published in Proceedings of CIPANP2000,
Quebec, May 22-28, 2000, requires aipproc.sty(included
Measurement of quasi-elastic 12C(p,2p) scattering at high momentum transfer
We measured the high-momentum quasi-elastic 12C(p,2p) reaction (at center of
mass angle near 90 degrees) for 6 and 7.5 GeV/c incident protons. The
three-momentum components of both final state protons were measured and the
missing energy and momentum of the target proton in the nucleus were
determined.
The validity of the quasi-elastic picture was verified up to Fermi momenta of
about 450 MeV/c, where it might be questionable. Transverse and longitudinal
Fermi momentum distributions of the target proton were measured and compared to
independent particle models which do not reproduce the large momentum tails. We
also observed that the transverse Fermi distribution gets wider as the
longitudinal component increases in the beam direction, in contrast to a simple
Fermi gas model.Comment: 4 pages including 3 figure
The Use of Helmholtz Resonance for Measuring the Volume of Liquids and Solids
An experimental investigation was undertaken to ascertain the potential of using Helmholtz resonance for volume determination and the factors that may influence accuracy. The uses for a rapid non-interference volume measurement system range from agricultural produce and mineral sampling through to liquid fill measurements. By weighing the sample the density can also measured indirectly
Energy Dependence of Nuclear Transparency in C(p,2p) Scattering
The transparency of carbon for (p,2p) quasi-elastic events was measured at
beam energies ranging from 6 to 14.5 GeV at 90 degrees c.m. The four momentum
transfer squared q*q ranged from 4.8 to 16.9 (GeV/c)**2. We present the
observed energy dependence of the ratio of the carbon to hydrogen cross
sections. We also apply a model for the nuclear momentum distribution of carbon
to normalize this transparency ratio. We find a sharp rise in transparency as
the beam energy is increased to 9 GeV and a reduction to approximately the
Glauber level at higher energies.Comment: 4 pages, 2figures, submitted to PR
Measurements of the Delta(1232) Transition Form Factor and the Ratio sigma_n\sigma_p From Inelastic Electron-Proton and Electron-Deuteron Scattering
Measurements of inclusive electron-scattering cross sections using hydrogen
and deuterium targets in the region of the Delta(1232) resonance are reported.
A global fit to these new data and previous data in the resonance region is
also reported for the proton. Transition form factors have been extracted from
the proton cross sections for this experiment over the four-momentum transfer
squared range 1.64 < Q^2 < 6.75 (GeV/c)^2 and from previous data over the range
2.41 < Q^2 < 9.82 (GeV/c)^2. The results confirm previous reports that the
Delta(1232) transition form factor decreases more rapidly with Q^2 than
expected from perturbative QCD. The ratio of sigma _n \sigma_p in the
\Delta(1232) resonance region has been extracted from the deuteron data for
this experiment in the range 1.64 < Q^2 < 3.75 (GeV/c)^2 and for a previous
experiment in the range 2.4 < Q^2 < 7.9 (GeV/c)^2. A study has been made of the
model dependence of these results. This ratio sigma_n\sigma_p for \Delta(1232)
production is slightly less than unity, while sigma_n\sigma_p for the
nonresonant cross sections is approximately 0.5, which is consistent with deep
inelastic scattering results.Comment: 10 figures. 42 pages, including figures. submitted to Physical Review
K+ Total Cross-Sections on C-12 and Medium Effects in Nuclei
Journals published by the American Physical Society can be found at http://publish.aps.org/The total cross sections for K+ mesons on carbon and deuterium nuclei have been measured at eleven momenta in the range 450-740 MeV/c. The experimental technique was of the standard transmission type. The K+ meson is the least strongly interacting of available hadronic probes, with a long mean free path in nuclear matter. At low incident momentum the K+ N interaction is dominated by the S11 phase shift and varies slowly with energy. These characteristics make the K+ an ideal tool for probing the nuclear volume to reveal nuclear medium effects. Measurements of the ratio of the total cross sections, per nucleon, of K+-C-12 to K+-d have been suggested as a way to reveal effects of the nuclear medium. The total cross section ratios are found to lie significantly above those predicted by the usual nuclear medium corrections. This suggests that novel phenomena axe taking place within the nucleus. Several models which incorporate such phenomena are discussed, including nucleon "swelling," mass rescaling, nuclear pions, and relativistic effects
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