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.
Inelastic cross sections at 60 and 200 GeV/nucleon are determined in a streamer chamber for 16 O on several nuclear targets. Charged particle multiplicity distributions for inelastic and central collisions are studied and compared with theoretical predictions. The inelastic cross section exhibit a geometrical dependence on nuclear radii. The multiplicity data are governed by the collision geometry. They are consistent with a picture of superposition of independent nucleon-nucleus interactions.
Minimum bias events.
Hard veto and hard Et events.
Transverse momentum ( p T ) distributions of inclusive photons and neutral pions at midrapidity are measured with a lead glass calorimeter in 60 and 200 A GeV 16 O + nucleus and proton + nucleus reactions . The variation of the average transverse momentum is investigated as function of centrality, determined by measurements of the remaining energy of the projectile and the charged particle multiplicity. For small values of the entropy, deduced from the multiplicity density, an increase in average p T is observed levelling off for larger values of entropy. The target-mass and energy dependence of π 0 p T distributions are presented.
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THE BETTER FIT FOR PI- AND BARIONBAR IS THE SUM OF TWO EXPONENT: A*EXP(-B1*PT**2)+D*EXP(-B2*PT**2).FOR PI- B1=30+-4 AND B2=6.3+-.3 .FOR BARIONBAR B1=46+-18 AND B2=3.9+-.5.
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No description provided.
New measurements of the total crosssections of charged-current interactions of muonneutrinos and antineutrinos on isoscalar nuclei have been performed. Data were recorded in an exposure of the CHARM d
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Using the ARGUS detector at DORIS, we observe the production of D ∗+ s mesons in e + e − annihilation through their subsequent decays to a D + s and a photon. Photons which convert in the beam pipe or drift chamber inner wall are used to obtain a high precision measurement of the D ∗+ s -D + s mass difference, while photons detected in the shower counters are used to determine the production cross section, and to provide an independent measurement of the D ∗+ s -D + s mass difference. The observed D ∗+ s - D + s mass difference is 142.5±0.8±1.5 MeV/ c 2 , and σ(e + e − →D ∗+ s X)·BR(D ∗+ s →D + s γ)(·BR(D + s →φπ + ) is 4.4±1.1±1.0 pb at 10.2 GeV. The width of the D ∗+ s is less than 4.5 MeV/ c 2 at 90% confidence level.
Cross sections uncorrected for branching ratios.
The reactions e + e − → μ + μ − and τ + τ − were measured at s =52 GeV and 55 GeV by using the TOPAZ detector at TRISTAN. For the combined data, the observed charge asymmetry is −0.29±0.13 and the total cross section is 27.9±3.0 (stat.)±0.8 (syst.) pb for μ + μ − production, and those for τ + τ − production are −0.20±0.14 and 35.7±4.3 (stat.)±2.4 (syst.)pb, respectively. These values are consistent with predictions by the standard model of electroweak interactions.
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Differential cross sections for the processes e + e − → e + e − (Bhabha scattering) and e + e − → γγ have been measured with the TOPAZ detector at s =52 GeV . The results agree with the predictions of quantum electrodynamics (QED). The lower limits for the QED cut-off parameters have been obtained to be Λ + ⩾115 GeV and Λ − ⩾236 GeV for Bhabha scattering, and Λ + ⩾94 GeV and Λ − ⩾59 GeV for the reaction e + e − → γγ .
Statistical errors only.
Statistical errors only.
Ratio of experimental data to prediction for lowest order QED. Statistical errors only.
Forum