Using a prototype of a large hadron calorimeter, vertical cosmic ray hadrons were recorded and the all-hadron flux was measured in the range from 5 GeV to 10 TeV. Hadron reconstruction and identification are described. We observe a vertical flux of dI/dEh=(1.59+or-0.24)*10-5(Eh/100 GeV)-2.72+or-0.10 (m2 s sr GeV)-1. The flux compares well with values obtained in other experiments. Total inelastic cross sections for protons scattered by nuclei in air are deduced from the unaccompanied hadron flux and compared with the values reported by other authors.
PROTON AIR CROSS SECTION.
Annihilation cross-sections σann for antineutrons on some nuclei (C, Al, Cu, Sn and Pb) at three antineutron momenta (180, 240 and 280 MeV/c) were measured at LEAR (CERN) with the OBELIX spectrometer. A behaviour σann=σ0Aν has been found withν≈2/3. The data are discussed following some models for antineutron-nucleus interaction.
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We present a total of 191 and 203 data points of the elastic neutron-protonspin correlation parameters A ookk and A oosk , respectively. Both observables were measured in a large angular interval. The observable A ookk was measured from 0.312 to 1.10 GeV and A oosk from 0.80 to 1.10 GeV. The SATURNE II polarized beam of free neutrons obtained from the break-up of polarized deuterons was scattered on the polarized Saclay frozen-spin proton target. The beam polarization was oriented either along the beam direction or sideways, the target polarization was oriented longitudinally. Data are compared with phase-shift analyses predictions and with the PSI, LAMPF and SATURNE II results. Present results provide an important contribution to any future theoretical or phenomenological analysis.
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Transverse momentum spectra of η mesons have been measured near the free nucleon-nucleon production threshold in the heavy ion reactions Ar40+ Canat, Kr86 + Zrnat, and Au197+ Au197 at 1.0A GeV and also in Ar40+ Canat at 1.5A GeV. The measured transverse momentum distributions are compared to model calculations. The relative abundance of Δ(1232) and N(1535) resonances excited in the collision is deduced. A comparison to pion data reveals scaling with the transverse mass of the emitted meson.
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Extrapolation to full solid angle.
We report on a measurement of the forward-backward charge asymmetry in e+e−→qq¯ at KEK TRISTAN, where the asymmetry is near maximum. We sum over all flavors and measure the asymmetry by determining the charge of the quark jets. In addition we exploit flavor dependencies in the jet charge determination to enhance the contributions of certain flavors. This provides a check on the asymmetries of individual flavors. The measurement agrees with the standard model expectations.
Forward--backward asymmetry summed over all flavours of quarks.
Using 773 muons found in hadronic events from 142 pb−1 of data at a c.m. energy of 57.8 GeV, we extract the cross section and forward-backward charge asymmetry for the e+e−→bb¯ process, and the heavy quark fragmentation function parameters for the Peterson model. For the analysis of the e+e−→bb¯ process, we use a method in which the behavior of the c quark and lighter quarks is assumed, with only that of the b quark left indeterminate. The cross section and asymmetry for e+e−→bb¯ are found to be Rb = 0.57 ± 0.06(stat) ± 0.08(syst) and Ab = −0.59 ± 0.09 ± 0.09, respectively. They are consistent with the standard model predictions. For the study of the fragmentation function we use the variable 〈xE〉, the fraction of the beam energy carried by the heavy hadrons. We obtain 〈xE〉c=0.56−0.05−0.03+0.04+0.03 and 〈xE〉b=0.65−0.04−0.06+0.06+0.05, respectively. These are in good agreement with previously measured values.
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Here X=E(hadron)/E(beam).
Inelastic ρ0 photoproduction in the reaction γp→ρ0π+n is observed in the peripheral region |tγ,ρ0′|<0.12 GeV2. The data are consistent with the ρ0 production being due to a double peripheral mechanism which conserves s-channel helicity. The π+n produced in association with the ρ0 is also consistent with the same mechanism, although there is a distortion of the expected angular distributions in the π+n mass region of 1.3-1.5 GeV/c2.
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Measurements have been made of inclusive 525 GeV π− interactions in emulsion. The results are compared to proton-emulsion and lower energy pion-emulsion data. Average multiplicities of relativistic shower particles increase with increasing energy, although with a somewhat steeper slope above 60 GeV than at lower energies. The ratio 〈ns〉p/〈ns〉π∼1.1 over the energy range 60–525 GeV. The ratio of the dispersion in the multiplicity distribution to the average multiplicity is the same for proton and pion collisions in emulsion, and is independent of projectile energy. The shape of the shower particle multiplicity distribution does not vary significantly with energy, and KNO scaling appears to hold over the energy range 60–525 GeV. The shower particle pseudorapidity distributions are independent of the beam energy in the target and projectile fragmentation regions, and both the pseudorapidity and multiplicity distributions agree reasonably well with the fritiof model predictions for 525 GeV pions. The dependence of the shower particle multiplicity 〈ns〉 on the number of heavy tracks Nh appraoches saturation as the total shower particle energy becomes a significant fraction of √s , and the pseudorapidity distributions shift toward smaller 〈η〉 with increasing numbers of grey and black tracks at 525 GeV. Neither the average number 〈Nh〉 nor the multiplicity distributions of the heavily ionizing tracks vary significantly with energy, and the normalized angular distributions of grey and black tracks are independent of the type of projectile or projectile energy.
NUCLEUS means average nuclei of BR-2 emulsion.
NUCLEUS means average nuclei of BR-2 emulsion.
NUCLEUS means average nuclei of BR-2 emulsion.
We have studied single photon production in e + e − annihilation based on a data sample corresponding to an integrated luminosity of 164.1 pb −1 at s =58 GeV . The single photon yield is consistent with the prediction of the standard model with three light neutrino species. No anomalous signal has been observed. From this result left- and right-handed scalar electrons in the mass degenerate case are excluded at 90% CL below 44.4 GeV/ c 2 for the massless photino.
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NET BARYON DENSITY D(N)/D(Y) HAS BEEN DETERMINED AT THE RAPIDITY OF NN C.M.S., FOR NET BARYON THE FORMULAR: 2*(P-PBAR)+1.6*(LAMBDA- LAMBDABAR) HAS BEEN USED.
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