117756001
New measurement of the total cross-section in proton proton scattering in pure spin states
119484082
Simultaneous Measurement of 2 and 3 Spins in Proton Proton Elastic Scattering at 6-GeV/c
The elastic cross section for proton proton scattering at 6 GeVc was measured using a 70% polarized beam and a 75% polarized target at the Argonne ZGS. In the range P⊥2 = 0.5 → 2.0(GeVc)2 we obtained small error measurements for the ↑↑, ↓↓ and ↑↓ initial spin states perpendicular to the scattering plane. At P⊥2 = 0.5 we also measured the recoil spin and found that the 5 different cross sections were very unequal.
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.
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.
120282404
A new multivariate technique for top quark search
Abstract We present a new multivariate event classifier, the PDE classifier, which can be used to identify rare signals in the presence of large backgrounds. The classifier is based on a discriminant function which uses kernel density estimates of the signal and background event densities. The PDE method offers the flexibility of a neural network but is conceptually simpler, theoretically better understood, and easier to optimize in practice. The technique is tested on Monte Carlo data using processes t t → e + E t + jets as signal and W + jets → e + Et + jets as background. The performance of the PDE classifier is similar to that of a neural network. Both methods outperform conventional analysis.
121132984
Hadron-nucleus scattering as a function of nuclear size☆
Abstract High-energy hadron-nucleus collisions, when viewed in terms of nuclear size, exhibit a remarkable simplicity. The data suggest that nuclear matter is extremely opaque to hadrons, and that fast-forward hadrons ( x ≳0.3) arise solely from peripheral collisions. This picture naturally explains why the production ratios of different hadron species are target independent at large x .
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.
122252484
Temperature measurement of quark-gluon plasma formed in high energy nucleus-nucleus collisions
We discuss lepton pair and real photon emission from quark-gluon plasma, which is very likely to be formed in high energy nucleus-nucleus collisions. Measurement of pair production crosssection will provide one with accurate information of the temperature of this plasma.
122328611
On the charge structure of high-energy multiple production
Correlations between neutral and charged particles produced in high-energy collisions are studied. The associated average multiplicity 〈n0〉n and the associated moment (f200) are expressed in terms of the Mueller moments. An isospin analysis of the pion - pion correlations is performed with the help of Mueller-Regge techniques. From this analysis, the slope of 〈n0〉n− is predicted to be asymptotically about 0.75. This asymptotic limit should be approached already at ISR energies. Finally, predictions are given for the associated moment (f200)n−, and the importance of the measurements of this quantity is emphasized.
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.
91843025
Diffractive processes and the triple-pomeron