Measurements of the production of high transverse momentum direct photons by a 515 GeV/c piminus beam and 530 and 800 GeV/c proton beams in interactions with beryllium and hydrogen targets are presented. The data span the kinematic ranges of 3.5 < p_T < 12 GeV/c in transverse momentum and 1.5 units in rapidity. The inclusive direct-photon cross sections are compared with next-to-leading-order perturbative QCD calculations and expectations based on a phenomenological parton-k_T model.
Invariant cross sections per nucleon for P BE collisions at 800 GeV.
Invariant cross sections per nucleon for P BE collisions at 530 GeV.
Invariant cross sections per nucleon for PI- BE collisions at 515 GeV.
Data on inclusive jet production in the transverse-momentum (p⊥) range 0-8 GeV/c for 200-GeV/c p, π−, π+, K−, K+, and p¯ incident on a hydrogen target are presented. The jet cross section is fully corrected for losses and biases, and compared with the predictions of a model based on quantum chromodynamics. Both the absolute cross section and the inclusive charged-particle distributions inside and outside the jet are in qualitative agreement with the model.
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We report on the experimental results obtained at the ISR for the η particle production at 90° and √ s = 30.6 and 53.2 GeV. We determine the invariant cross section and the p t distribution in the interval 1 ⩽ p t ⩽ 5 GeV/ c . We find that the p t distribution has the same shape of the π 0 production and differ from it by a constant factor R 90° = 0.5 ± 0.07.
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We report the results of an experiment made at the CERN ISR to investigate the possible diret production of single photons in pp collisions at √ s = 53.2 GeV at 90° and in the p t interval 2.3 to 5.7 GeV/ c . The value of the ratio R = n γ / n π 0 is compatible with zero for low p t ⪅ 3 GeV/ c but, in spite of the large error, shows a trend to increase for larger p t .
THIS USES THE SO-CALLED D2L TRIGGER (SEE PAPER).
THIS USES THE SO-CALLED D2MAX TRIGGER (SEE PAPER).
THIS USES THE SO-CALLED D2MAX TRIGGER (SEE PAPER).
Measurements are presented of the inclusive π 0 production cross section, in the transverse momentum range 2.3 ⪅ p T ⪅4.5 GeV/c, for dd and dp interactions at total c.m. energies of √ s = 52.7 GeV and √ s = 63.2 GeV and for pp interactions at √ s = 52.7 GeV. The produced π 0 's are detected by identifying both protons from the decay π 0 → γγ . As in pp interactions, the data can be adequately described by a p T −n ƒ(x T ) dependence with n ≌ 8 . The data are approximately consistent with the expectations of free nucleon scattering. No significant differenceare observed in either the charged or the neutral particle distributions associated with π 0 , for dd, dp and pp interactions.
GLOBAL NORMALIZATION UNCERTAINTY = 12 PCT. RELATIVE NORMALIZATION UNCERTAINTY = 5 PCT.
GLOBAL NORMALIZATION UNCERTAINTY = 10 PCT. RELATIVE NORMALIZATION UNCERTAINTY = 6 PCT.
GLOBAL NORMALIZATION UNCERTAINTY = 15 PCT. RELATIVE NORMALIZATION UNCERTAINTY = 7 PCT.
Measurements of the double differential cross sections for ππ and pπ production in pp collisions at the CERN ISR are presented for 5 c.m. energies s = 22, 30, 44, 53, 62 GeV . Charge and transverse momentum correlations are also reported.
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We present a comparative study of inclusive and semi-inclusive pion production in pp collisions at 102 and 400 GeV/ c . In particular, we examine the correlation between transverse and longitudinal momentum variables and the energy dependence of invariant cross sections.
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We have performed a simultaneous measurement of the large transverse momentum (1.6 to 3.8 GeV/ c ) yields of single photons and of photon pairs at 90° production angle in pp collisions at ISR energies. Production cross sections for each of these two processes are compared.
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The inclusive production of low-momentum charged pions, kaons, and protons has been measured at x = 0 over the ISR energy range 23 < √ s < 63 GeV. The average increase in the invariant differential cross section is 36 ± 2% for π + , 41 ± 2% for π − , 52 ± 8% for K + , 69 ± 8% for K − , 8 ± 5% for p, and 84 ± for p ̄ . Pions have been measured in the range 0.04 < p T < 0.4 GeV/ c , kaons over 0.1 < p T < 0.3 GeV/ c , and nucleons over 0.1 < p T < 0.5 GeV/ c .
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As part of a study of large p T phenomena in photon-proton collisions at the CERN ISR, a search for direct single photon production has been performed. A statistical division of the data sample into the fraction consistent with single photon and the fraction due to multiphoton decays of neutral hadrons is accomplished by measuring the average conversion probability for the sample in a one radiation length thick converter. The fraction of the sample attributable to direct single photon production is 〈 γ /all〉 = 0.074 ± 0.012 for 6 GeV/ c < p T 10 GeV/ c , and 〈 γ /all〉 = 0.26 ± 0.04 for p T > 10 GeV/ c , with an additional systematic uncertainty of ±0.05 for both values.
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