π0production indC- anddCu-interactions at a momentum of 4.5 GeV/c per nucleon

Abstract

We report on measurements of neutral pion production in the inclusive reactions d + C → π 0 + x and d + Cu → π 0 + x at an incident momentum of 4.5 GeV/c per nucleon. The experiments were performed on the LHE 90-channel lead glass γ -spectrometer. The cross sections were measured over the kinematical region specified by the inequalities θπ ≤ 16° and Eπ ≥ 2 GeV (in the laboratory frame). The cumulative number and transverse momentum dependencies of the exponent n in the invariant cross section parameterization Ed 3 σ / d 3 p ~ A t n are investigated by comparing of the observed cross sections for π 0 production on carbon and copper targets in the intervals 0.6 ≤ X ≤ 1.8 and 0.04 ≤ p T 2 ≤ 0.40 (GeV/c)2 . The double differential cross section for the reaction d + C → π 0 + x is measured using statistics of about 4.5 · 104 π 0 mesons. On the basis of these data we verified the so-called cluster mechanism of π 0 production. We have compared our data for the reaction d + C → π 0 + x , extrapolated to θπ = 0°, with the data from another experiments on π − production: d + C → π − (0°) + x (P = 1.75 and 2.88 GeV/c per nucleon) [1]; p + d → π − (180°) + x and p + d → π + (180°) + x (P = 8.9 GeV/c per nucleon) [2]; d + p → π − (0°) + x (P = 8.9 GeV/c per nucleon) [3]. The invariant cross sections were approximated by an exponential function Ed 3 σ / d 3 p ~ exp (−X / X 0 ). The slope parameter X 0 at different kinetic energies of the projectiles in the range of 1.05÷8.0 GeV per nucleon is determined.