Yields of projectile fragments in sulphur-emulsion interactions at 3.7 A GeV

This work presents the basic characteristics of singly,doubly and heavily charged projectile fragments(PFs) emitted in inelastic interactions of ~(32)S ions with photo-emulsion nuclei at Dubna energy(3.7 A GeV).Our experimental data are compared with the corresponding data for other projectiles at the same incident energy.The study of mean multiplicities of different charged PFs against the projectile mass shows a power-law relationship.The multiplicity distributions of singly and doubly charged PFs have been fitted well with a Gaussian distribution function.The yields of PFs broken up from the interactions of ~(32)S projectile nuclei with different target nuclei are studied.The beam energy dependence in terms of the various order moments is studied as well.     

Angular distributions in proton-nucleus interactions in emulsion at 800 GeV

Data on angular distributions of heavily ionizing and shower particles in incoherent protonnucleus collisions in emulsion at 800 GeV are reported and discussed in details. Dependence of angular distributions on the mass number of a target nucleus and on the multiplicity of charged particles is investigated. The data presented are systematically compared with results of emulsion experiments at lower energies and with predictions of the Lund Monte Carlo model FRITIOF.     

Angular distributions of fission and deep inelastic products of the system Ar+Au at 285 MeV

The angular distribution of the heavy products from the interaction of 285 MeV ions⁴⁰Ar on an Au target has been analysed through a large angular range (4°–165° lab angles). The results exhibit two components: the fission component corresponding to relatively symmetric masses, and a deep inelastic one which peaks in the angular range 100°–140° (c.m angles). The fission component exhibit the usual 1/sinθ pattern, proving that, in spite of a zero fission barrier, the life time of the system exceeds the rotation period. The relative cross sections for the fission and deep inelastic processes are discussed.     

Investigation of the mean free path of projectile fragments produced in 16O－Em collision at 60 A GeV

Results are presented for an investigation of the mean free path of projectile fragments with charge 3≤Z≤8, produced by 60 A GeV {}^{16}O in nuclear emulsion. No dependence of mean free path on the distance from the point of the fragment emission is observed and our result is consistent with the nonexistence of anomalons.     

Study of projectile fragmentation in the reaction (158 A GeV) Pb + Pb using CR-39

The fragmentation of Pb ions at 158 A GeV energy produced in the interaction with Pb target has been studied using a CR-39 track detector. A stack comprising of 64 detectors was prepared such that a target of 1 cm thickness was sandwiched between the sheets of CR-39. The purpose of this exposure geometry was to calibrate CR-39 with respect to relativistic heavy ions as well as to study the fragmentation of Pb ions at 158 A GeV energy. The exposure was carried out at the SPS beam facility of CERN at normal incidence with a fluence of . Two detectors from the exposed stack have been selected for this study: one before and the other after the target material. After etching, the detectors were scanned using an optical microscope and the etched track lengths and the diameters of the track openings were measured manually. Considering that the lengths of tracks provide the best charge resolution for Z>65, we have measured track lengths for a sufficiently large number of fragments to identify individual charge states for 65<Z<83. The total charge-changing cross section has also been determined.     

Production of helium projectile fragments in {16O－emulsion interactions at 4.5 A GeV/c

The measurements of partial production cross sections of the multiple helium projectile fragments emitted at 4.5 A GeV/c {}^{16}O－Em interactions are reported. We have studied the production rate of helium projectile fragments due to fragmentation of {}^{16}O ions and compared it with that obtained from different projectiles at various energies. The dependence of on the mass number of the incident beams is formulated. The multiplicity distributions of the helium fragments produced in {}^{16}O－Em interactions at different energies exhibit Koba－Nielson－Olesen (KNO) scaling. The correlation of helium projectile fragments and target fragments is also investigated and it is found that the average of target fragments is increased with the decrease of the number of helium fragments in peripheral interactions.     

Angular and current-target correlations in deep inelastic scattering at HERA

Correlations between charged particles in deep inelastic scattering have been studied in the Breit frame with the ZEUS detector at HERA using an integrated luminosity of 6.4 pb. Short-range correlations are analysed in terms of the angular separation between current-region particles within a cone centred around the virtual photon axis. Long-range correlations between the current and target regions have also been measured. The data support predictions for the scaling behaviour of the angular correlations at high and for anti-correlations between the current and target regions over a large range in and in the Bjorken scaling variable x. Analytic QCD calculations and Monte Carlo models correctly describe the trends of the data at high , but show quantitative discrepancies. The data show differences between the correlations in deep inelastic scattering and annihilation. Received: 18 May 1999 / Published online: 3 November 1999     

Leading particle distributions in 200 GeV/c p+A interactions

Distributions of the leading positive particle have been measured in collisions of a 200 GeV/c proton beam with hydrogen, Mg, Ag and Au targets using the FNAL Hybrid Spectrometer. Estimates of the rapidity loss of the projectile have been obtained as a function of the target mass, the multiplicity of negative particles and the number of recoil protons. We obtained a lower limit of the rapidity loss of 2.0±0.2 for central p+Au collisions. The impact parameter dependence of the momenta of the first few leading particles has also been investigated with important implications to estimates of energy densities obtained in central collisions.     

Hadron production in 200 GeV μ-copper and μ-carbon deep inelastic interactions

The measurements of the z and p_T² distribution of hadrons produced in the interactions of 200 GeV muons with copper and carbon nuclei are shown in different x_Bj and virtual photon energy intervals. Effects of the jet scattering are seen at the lowest virtual photon energies while for energies above 70 GeV there is no evidence of these effects. Comparison with a theoretical model indicates that at high jet energies the parton fragmentation distance is greater than the nuclear radius and that the parton absorption cross section is less than 10 mb.     

Angular distributions in the dimuon hadronic production at 150 GeV/c

From π^- interactions at 150 GeV/c on a heavy target, we present the final analysis of the dimuon decay angular distribution in the mass interval 4.5–8.5 GeV/c². Results are presented and discussed in various reference frames and are also given in terms of the density matrix elements. Finally the possible contribution of higher-twist effects at largex ₁ is discussed; we find that our data are not compatible with higher twist contributions as proposed by the Berger and Brodsky Model.     

A microscopic calculation of angular and energy distributions of light fragments in deeply inelastic heavy-ion reactions

A random-matrix model for the form factors connecting channels corresponding to high intrinsic excitation energy of either fragment is used to calculate energy-averaged cross sections in deeply inelastic heavy-ion reactions. The distribution of the form factors is determined microscopically. The calculation yields differential cross sections without any fit parameters. Results for Kr- and Bi-induced reactions are compared with the data.     

Cross sections and multiplicity distributions forK + p interactions at 70 GeV/c

Cross sections and charged multiplicity distributions forK ⁺ p interactions at 70 GeV/c are presented and compared withK ⁺ p data at other energies. Comparisons are also made with available π⁺ p,pp, andK ^? p data.     

Charged multiplicity distributions in pd and π+d interactions at 195 GeV/c

Topological inelastic cross-sections and average multiplicities for pd and π⁺d interactions at 195 GeV/c, are obtained from an exposure of the NAL 30″ proportional wire chamber-bubble chamber hybrid system to a positive π⁺/p beam. We find that 〈n_c〉_pn = 7.67 ± 0.25, and 〈n_c〉_π⁺n = 7.56 ± 0.30, yielding a negative multiplicity difference between pn and pp of 0.50 ± 0.14, and that σ_n(pp) is approximattely interleaved between σ_n?1(pn).     

Two source emission behavior of projectile fragments alpha in 84Kr interactions at around 1 GeV per nucleon

The emission of projectile fragments alpha has been studied in ⁸⁴Kr interactions with nuclei of the nuclear emulsion detector composition at relativistic energy below 2 GeV per nucleon. The angular distribution of projectile fragments alpha in terms of transverse momentum could not be explained by a straight and clean-cut collision geometry hypothesis of Participant — Spectator (PS) Model. Therefore, it is assumed that projectile fragments alpha were produced from two separate sources that belong to the projectile spectator region differing drastically in their temperatures. It has been clearly observed that the emission of projectile fragments alpha are from two different sources. The contribution of projectile fragments alpha from contact layer or hot source is a few percent of the total emission of projectile fragments alphas. Most of the projectile fragments alphas are emitted from the cold source.     

Omega- and Omega+ production in central Pb + Pb collisions at 40 and 158A GeV

Results are presented on Omega production in central Pb+Pb collisions at 40 and 158A GeV beam energy. For the first time in heavy ion reactions, rapidity distributions and total yields were measured for the sum Omega(-) + Omega(+) at 40A GeV and for Omega(-) and Omega(+) separately at 158A GeV. The yields are strongly underpredicted by the string-hadronic UrQMD model but agree better with predictions from hadron gas models.     

Interferometry of direct photons in central 208Pb + 208Pb collisions at 158A GeV

Two-particle correlations of direct photons were measured in central 208Pb+208Pb collisions at 158A GeV. The invariant interferometric radii were extracted for 100相似文献   

Multiplicity distributions in rapidity intervals forp-p andp-nucleus interactions at 200 GeV

Multiplicity distributions of charged particles produced in proton-proton, proton-argon and proton-xenon inelastic collisions at 200 GeV/c in various rapidity intervals are presented. Nuclear target data are analysed separately for the forward and the backward hemispheres. Results of a similar analysis for only negative particles are shown. The data are well parametrized in terms of negative binomial distributions. However, such a parametrization fails in describing thep-nucleus multiplicity distributions of charged particles for large rapidity intervals comprising both hemispheres. Parameters characteristic for the clan model of Giovannini and Van Hove are also presented.     

A study of angular correlations of projectile and target fragments in 1.4 A GeV Kr+Ag(Br) collisions

A sample of high multiplicity quasi-central Kr⁸⁴+Ag(Br) interactions has been'analysed in terms of angular correlations between projectile and target fragments. The azimuthal correlation of PFs and TFs suggests the presence of a weak collective (bounce-off) effect. Other observations like, target recoil velocity,F/B ratio of TFs with respect to direction of their source etc. are interpreted in terms of a simple two body quasi-elastic scattering and a modified Maxwell-Boltzmann distribution.     

Measurement of angular distributions of Drell-Yan dimuons in p+d interactions at 800 GeV/c

We report a measurement of the angular distributions of Drell-Yan dimuons produced using an 800 GeV/c proton beam on a deuterium target. The muon angular distributions in the dilepton rest frame have been measured over the kinematic range 4.5相似文献