120443824
Measurement of proton-proton elastic scattering at 6 GeV/c in polarized initial and final spin states
The differential elastic $p\ensuremath{-}p$ scattering cross section was measured at 6 GeV/c at the Argonne Zero Gradient Synchrotron in the range $P_{\ensuremath{\perp}}^{}{}_{}{}^{2}=0.60\ensuremath{-}1.0$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$ using a 65% polarized target and a 75% polarized proton beam of intensity 3 \ifmmode\times\else\texttimes\fi{} ${10}^{9}$ protons/pulse. The polarization of the recoil proton was simultaneously measured with a well calibrated carbon-target polarimeter. All three polarizations were measured perpendicular to the horizontal scattering plane. Our results indicate that $P$ and $T$ invariance are both obeyed to good precision even at our largest $P_{\ensuremath{\perp}}^{}{}_{}{}^{2}$. Parity invariance implies that the eight single-flip transversity cross sections are zero, so our data gives the magnitudes of the eight remaining pure spin cross sections where all spins are measured. We find that the four double-flip transversity cross sections are nonzero.
120544624
Triggering on high-transverse-momentum jets
We compare the characteristics of events selected by ''global'' and ''two-high'' triggers in large-transverse-energy hadron-hadron collisions. Using a QCD-based Monte Carlo model of Fox and collaborators, we find that the former is effectively a high-multiplicity trigger, the latter a high-planarity trigger favoring unusually clean jet events. Predictions of the model for both triggers are in good qualitative agreement with recent data.
198138883
Experimental information on the pion gluon distribution function
An experiment performed at Fermilab used double-arm calorimeter triggers to study di-jet production by 400 GeV protons and 200 GeVπ− mesons incident on liquid hydrogen. The observed ratio of positive to negative leading particles in the jets was compared forpp andπp production using a tree level parton scattering model. The results are moderately sensitive to the form of the pion gluon distribution function and yieldx g(x)⋍(1−x)2.75±0.40±0.75.
119722876
Measurement of the dijet cross section in 400-GeV pp collisions
The invariant cross section for production of jet pairs in 400-GeV/c pp interactions has been measured as a function of p{tau} in the p{tau} range 4 to 9 GeV/c. The results are in good agreement with predictions of perturbative QCD models. 20 refs., 3 figs., 1 tab.
125525593
HADRON JETS IN 400-GeV p p COLLISIONS
120365910
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.
123478569
Coherent production on nuclei does not measure total cross sections for unstable particles
We calculate diffractive production in nucleon-nucleus collisions using a parton model. We fit the result by the standard optical-model formula, and obtain estimates of 12--30 mb for the cross section of the diffractively produced system on a nucleon. The actual value of that cross section in the model is 65 mb. Estimates for the total cross section of an unstable hadron which are based on the A dependence of coherent production should therefore not be trusted.
121736887
Diffraction scattering and the parton structure of hadrons
We apply parton-model concepts to the ''soft'' (small-momentum- transfer) processes which make up the majority of the hadronic total cross section. Diffraction is calculated as the shadow of these soft processes. We obtain an attractive picture of the essential features of total, elastic, and diffractive-inelastic scattering. In particular, the rather large cross section for inelastic diffraction, which is observed experimentally, results from fluctuations in the distribution of the wee partons which initiate interactions. These fluctuations lead to diffractive production by the mechanism of Good and Walker. The observed peripheral character of diffraction as a function of impact parameter, the absence of a forward dip in dsigma/dt dm/sup 2/, the correct integrated cross section, and the correct small-t slope of diffraction all follow naturally in our approach.
124906083
Geometrical description of hadronic collisions
120158411
Structure of two-body correlations in high energy hadron production
Abstract Experimental information on diffraction is used to estimate long range effects in multiparticle production. Diffractively produced secondaries are found to produce a plateau in the central region. Diffraction accounts for 30% of the observed correlations and the remainder, consistent with being short range, corresponds to a cluster size of 2.4 charged particles.
121701561
Unitarity bounds for inelastic diffraction
Unitarity in the s-channel is invoked to derive an upper bound for the inelastic diffractive cross-section as a func- tion of impact parameter. The application of this bound to high-energy proton-proton scattering strongly suggests that inelastic diffraction should be peripheral in the impact parameter space. Introduction. Recent observation of a structure around t = -0.2 GeV 2 in the differential cross-section of the process pp ~ p(n,r +) at the CERN ISR (1 ) sup- ports the assumption that inelastic diffraction, unlike elastic diffraction, is peripheral in the impact param- eter space. This assumption has been made very plaus- ible in the past by many authors (2-6), partially on intuitive grounds, partially on the basis of phenome- nological analyses of experimental data. In this letter we suggest that the previous conclu- sion is in fact a very natural consequence of s-channel unitarity and of the assumption that inelastic, as well as elastic diffraction, is the shadow of non-diffractive particle production. Using these assumptions, Pumplin has recently derived the following bound (7) :