Highly inelastic processes in hadron-nucleus reactions at several GeV have been studied by measuring multi-particle emission in the target-rapidity region. Events with no leading particle(s) but with high multiplicities were observed up to 4 GeV. Proton spectra from such events were well reproduced with a single-moving-source model, which implied possible formation of a local source. The number of nucleons involved in the source was estimated to be (3–5)A 1 3 from the source velocity and the multiplicity of emitted protons. In those processes the incident energy flux seemed to be deposited totally or mostly (>62;75%) in the target nucleus to form the local source. The cross sections for the process were about 30% of the geometrical cross sections, with little dependence on incident energies up to 4 GeV and no dependence on projectiles (pions or protons). The E 0 parameter in the invariant-cross-section formula E d 3 σ /d p 3 = A exp (− E / E 0 ) for protons from the source increases with incident energy from 1 to 4 GeV/ c , but seems to saturate above 10 GeV at a value E 0 = 60–70 MeV. Three components in the emitted nucleon spectra were observed which would correspond to three stages of the reaction process: primary, pre-equilibrium and equilibrium.
BEAM ERROR D(P)/P = 0.300 PCT. X ERROR D(EKIN)/EKIN = 8.00 PCT.
BEAM ERROR D(P)/P = 0.300 PCT. X ERROR D(EKIN)/EKIN = 8.00 PCT.
BEAM ERROR D(P)/P = 0.300 PCT. X ERROR D(EKIN)/EKIN = 8.00 PCT.
Particle production in proton-induced reactions at 14.6 GeV/c on Be, Al, Cu, and Au targets has been systematically studied using the E-802 spectrometer at the BNL-Alternating Gradient Synchrotron. Particles are measured in the angular range from 5° to 58° and identified up to momenta of 5, 3.5, and 8 GeV/c for pions, kaons, and protons, respectively. Mechanisms for particle production are discussed in comparison with heavy-ion-induced reactions at the same incident energy per nucleon.
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Measurements of the invariant cross sections for the reaction p(400 GeV)+(Li6, Be,C,Al,Cu,Ta)→(π±, K±)+X at laboratory angles from 70° to 160° are reported. Upper limits for p¯ production are given. Comparisons of the data are made using several scaling variables. NUCLEAR REACTIONS Inclusive cross section; 400 GeV incident protons; Li6, Be, C, Al, Cu, Ta targets; production of π, K, and p¯; lab angles 70° to 160°.
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An enormous enhancement of antiproton production in deuteron- and α-induced reactions has been observed in the subthreshold energy region between 2 and 5 GeV/nucleon. Antiprotons produced at 5.1° with a momentum range of between 1.0 and 2.5 GeV/ c were measured by a beam-line spectrometer and identified by the time-of-flight method. The production cross sections in the deuteron- and α-induced reactions at an incident energy of 3.5 GeV/nucleon were 2 and 3 orders of magnitude larger than those in proton-induced reaction at the same energy. The enhancement in light-ion reactions could not be explained by the internal motion in the projectile and target nuclei. The target-mass dependence (C, Al, Cu and Pb) of the cross sections has also been studied. Further, the cross sections of π and K productions were measured.
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Axis error includes +- 0.0/0.0 contribution (?////DUE TO UNACCURASY IN OUTGOING PARTICLES MOMENTUM).
Axis error includes +- 0.0/0.0 contribution (?////DUE TO UNACCURASY IN OUTGOING PARTICLES MOMENTUM).
Axis error includes +- 0.0/0.0 contribution (?////DUE TO UNACCURASY IN OUTGOING PARTICLES MOMENTUM).
A precision measurement of the double-differential production cross-section, ${{d^2 \sigma^{\pi^+}}}/{{d p d\Omega}}$, for pions of positive charge, performed in the HARP experiment is presented. The incident particles are protons of 12.9 GeV/c momentum impinging on an aluminium target of 5% nuclear interaction length. The measurement of this cross-section has a direct application to the calculation of the neutrino flux of the K2K experiment. After cuts, 210000 secondary tracks reconstructed in the forward spectrometer were used in this analysis. The results are given for secondaries within a momentum range from 0.75 GeV/c to 6.5 GeV/c, and within an angular range from 30 mrad to 210 mrad. The absolute normalization was performed using prescaled beam triggers counting protons on target. The overall scale of the cross-section is known to better than 6%, while the average point-to-point error is 8.2%.
Double differential PI+ production cross section in the angular range 30 to 60 mrad.. Errors shown are point-to-point only.
Double differential PI+ production cross section in the angular range 60 to 90 mrad.. Errors shown are point-to-point only.
Double differential PI+ production cross section in the angular range 90 to 120 mrad.. Errors shown are point-to-point only.
High yields of low-momentum pions were obtained from high-energy primary proton beams. The results are discussed, also with respect to the possibility of setting up cloud muon beams from the very lowmomentum poins produced by 10 GeV/c protons.
Data obtained with 30 cm long target.
The production of π±,K±,p has been measured in p+Be and p+Au collisions for comparison with central Si+Au collisions. The inverse slope parameters T0 obtained by an exponential fit to the invariant cross sections in transverse mass are found to be, T0p,K+,ππ∼140–160 MeV in p+A collisions, whereas in central Si+Au collisions, T0p,K+∼200–220 MeV >T0ππ∼140–160 MeV at midrapidity. The π± and K+ distributions are shifted backwards in p+Au compared with p+Be. A gradual increase of (dn/dy)K+ per projectile nucleon is observed from p+Be to p+Au to central Si+Au collisions, while pions show no significant increase.
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The analyzing powers of π+ and π− were measured using an incident 22−GeV/c transversely polarized proton beam at the Brookhaven Alternating Gradient Synchrotron. A magnetic spectrometer measured π± inclusive asymmetries on a hydrogen and a carbon target. An elastic polarimeter with a CH2 target measured pp elastic-scattering asymmetries to determine the beam polarization using published data for the pp elastic analyzing power. Using the beam polarization determined from the elastic polarimeter and asymmetries from the inclusive spectrometer, analyzing powers AN for π± were determined in the xF and pT ranges (0.45–0.8) and (0.3–1.2 GeV/c), respectively. The analyzing power results are similar in both sign and character to other measurements at 200 and 11.7 GeV/c, confirming the expectation that high-energy pion inclusive analyzing powers remain large and relatively energy independent. This suggests that pion inclusive polarimetry may be a suitable method for measuring future beam polarizations at BNL RHIC or DESY HERA. Analyzing powers of π+ and π− produced on hydrogen and carbon targets are the same. Various models to explain inclusive analyzing powers are also discussed.
Analyzing power measurements for PI+ and PI- production on the carbon target at incident momentum 21.6 GeV. See text of article for definitions of method 'A' and 'B'.
Analyzing power measurements for inclusive PI- production from the hydrogen target.
Analyzing power measurements for inclusive PI+ production from the hydrogen target.
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