The total cross section of hadron photoproduction on C, Cu and Pb nuclei is measured for six energy values in the range 12–30 GeV. The obtained cross-section values for C and Cu nuclei have a weak energy dependence at high energies (above 20 GeV). The cross section for the Pb nucleus is somewhat higher in comparison with that expected, and energy dependence is not observed. The A -dependence of the effective number of hadrons agrees with VDM predictions.
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A-EFFECTIVE/A = SIG(GAMMA A)/(Z*SIG(GAMMA P) + (A-Z)*SIG(GAMMA N)) WHERE SIG(GAMMA P) = (98.7 +- 3.6) + (65 +- 10)/SQRT(P) MUB, SIG(GAMMA N) = SIG(GAMMA P) - (18.3 +- 6.1)/SQRT(P) MUB AND A IS 12, 64 AND 207 FOR THESE NUCLEI.
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FROM LEGENDRE POLYNOMIAL FIT TO D(SIG)/DOMEGA, USING VALUE AT THETA = 0 DEG OBTAINED BY ADDITION OF THE PI+ P AND PI- P FORWARD SCATTERING AMPLITUDES GIVEN BY DISPERSION RELATIONS.
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MISPRINT CORRECTED DATA PRESENTED BY D.I.PATALAKHA.
Inclusive charged pion production is studied in an exposure of BEBC, filled with hydrogen, to an incidentK+ beam of 70 GeV/c. Total cross sections for pion production and inclusive longitudinal and transverse momentum distributions of π−'s and of positive particles are presented and compared with data at lower energies. Earlier evidence for scaling in the fragmentation regions is confirmed. The central region π− cross section increases proportionally topLAB−1/4; positive particles show almost no energy dependence atx=0. Particle ratios π+/π− are studied as a function ofx andy* and a comparison with 70 GeV/cK−p data is made. Analysis of structure functions for (ππ) pairs and of particle production associated with π± triggers at large |x| in the context of quark/parton models, provides qualitative evidence for the diquark-quark structure of the proton.
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Axis error includes +- 4/4 contribution (MEASUREMENT OF DEUTERIUM DENSITY).
A high precision measurement of the υ-meson mass has been performed at the storage ring VEPP-4 using the MD-1 detector. The resonance depolarization method has been used for the absolute calibration of the beam energy that allowed to improve the accuracy of υ-mass measurement by a factor of ten. The following mass value has been obtained: M = 9459.7 ± 0.6 MeV.
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Axis error includes +- 0.0/0.0 contribution (?////NOT GIVEN).
Axis error includes +- 0.0/0.0 contribution (?////NOT GIVEN).
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No description provided.
The forward production of charm states in 350 GeV p-Fe interactions has been studied via the production of prompt single muons with momentum p ≳ 20 GeV/ c . The data indicate equal production of single μ + and μ − events. The observed momentum distributions can be fit with the hypothesis that D mesons are produced with an invariant cross section proportional to (1 − x F ) 5.0±0.8 exp[−(2 ± 0.3) P t ] and do not favor a large diffractive cross section predicted by intrinsic charm models. Extrapolation of the distributions to x F = 0 yields a total D D production cross section of 22.6 ± 2.1(±3.6)ωb/nucleon on the assumption of a linear A dependence and 8% average semileptonic branching ratio of charm states.
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Lambda-hyperon and K°-meson production effective cross sections in Interactions of relativistlc carbon nuclei, measured using a 2-meter propane bubble chamber, appear to be <^c « (24+6) mb; <7°°0- (30 ±10) mb. They are In fair agreement with the predictions of the flrestreak model making use of the hypothesis on chemical equilibrium and associative production of strange particles. It means that strange particle production In CC-lnteractlons at 4.2 GeV/c momentum per nucleon Is well described without Invoking hypothesis about the quark-gluon phase transition.
No description provided.