Pion production inppcollisions at102 GeVc

Abstract

2 3~o r relativistic particles the distribution of L. Landau [J. Phys. 3, 201 (1944)1, a s tabulated by W. Borsch-Supan [J. Res. Natl. Bur. Stand. =, 245 (1961)1, is used. For other particles the distribution of P. V. Vavilov, Zh. Eksp. Teor. Fiz. 32, 920 (1957) [Sov. Phys.-JETP 5, 749 (1957)1, is used. 2 4~. Porat and D. Ouimette, SLAC Technical Note No. SLAC-TN-71-13 (unpublished).We present preliminary results on single-pion production and two-pion correlations making use of a 30 000-picture exposure of the ANL/NAL 30-in. hydrogen bubble chamber to 102-GeV/c protons. The data, when compared with those from lower energies, indicate approximate scaling of a-production in the proton-fragmentation region, but show a continuing rise of the cross section at y,,, = 0. Stronger correlations are observed between pions of opposite charge than between pions of like charge. The variation with energy of the charge transferred between c.m. hemispheres is slow, as would be predicted by multiperipheral-type models.

Charged pion production in p+C collisions at 158 GeV/c beam momentum: Discussion

“…In fact the correlation factor b increases steadily with √ s and reaches a value of b = 0.31 at √ s = 62 GeV. It has been established [11] that this increase is not accompanied by an extension of the feed-over range in x F by showing that the correlation vanishes by replacing the cut at |η| > 1 by an s-dependent Figure 6: Forward-backward multiplicity correlations, a) to d) experimental data and fits, [8][9][10][11]; f) to h) correlation with rapidity selection as given, [9][10][11]; d) x F as a function of p T at y = 1 for beam momentum between 205 and 306 GeV/c one at |η| > 0.5 ln s − 2 . This cut happens to correspond in first order to an s-independent x F cut at 0.05.…”

“…A series of bubble chamber experiments [8,9,10] at SPS energies, and a streamer chamber experiment at the ISR [11] have extended the study of [7] to full phase space by establishing multiplicity correlations between the forward and the backward hemisphere. In experiments [8][9][10] the complete x F region is accessible by momentum measurement in the fixed-target laboratory frame.…”

“…In experiments [8][9][10] the complete x F region is accessible by momentum measurement in the fixed-target laboratory frame. Since there is no particle identification available, the assumption of pion mass for the necessary Lorentz transformation creates a certain but practically negligible bias in the determination of central rapidity.…”

Inclusive production of charged pions in p+p collisions at 158 GeV/c beam momentum

“…The target was filled with para-Hydrogen obtained in a closed-loop liquefaction system which was operated at 75 mbar overpressure with respect to atmosphere. This results, at the mean atmospheric pressure of 965 mbar measured over the running periods of the experiment, in a density of ρ H = 0.0707 g/cm 3 . In addition, the cross section determination has to take into account the density of gaseous hydrogen ρ ET present in the empty target runs.…”

“…where ∆p 3 is the finite volume element defined by the experimental bin width, σ trig the trigger cross section discussed in Section 3.3, N ev the number of events originating from the liquid hydrogen target, and ∆n the number of identified pions from the target measured in the bin ∆p 3 . In general and for arbitrary functional shapes of f (x F , p T ), the measured quantity f meas depends on the bin width ∆p 3 via E and ∆n.…”