Multiplicities of charged hadrons produced in deep inelastic muon scattering off a $^6$LiD target have been measured as a function of the DIS variables $x_{Bj}$, $Q^2$, $W^2$ and the final state hadron variables $p_T$ and $z$. The $p_T^2$ distributions are fitted with a single exponential function at low values of $p_T^2$ to determine the dependence of $\langle p_T^2 \rangle$ on $x_{Bj}$, $Q^2$, $W^2$ and $z$. The $z$-dependence of $\langle p_T^2 \rangle$ is shown to be a potential tool to extract the average intrinsic transverse momentum squared of partons, $\langle k_{\perp}^2 \rangle$, as a function of $x_{Bj}$ and $Q^2$ in a leading order QCD parton model.
PT dependences of the differential multiplicities for 0.0045 < x_Bjorken < 0.0060 and 1.00 < Q^2 < 1.25 GeV^2 for Positive hadrons.
PT dependences of the differential multiplicities for 0.0060 < x_Bjorken < 0.0080 and 1.00 < Q^2 < 1.30 GeV^2 for Positive hadrons.
PT dependences of the differential multiplicities for 0.0060 < x_Bjorken < 0.0080 and 1.30 < Q^2 < 1.70 GeV^2 for Positive hadrons.
A study of strange particle production in muon neutrino charged current interactions has been performed using the data from the NOMAD experiment. Yields of neutral strange particles K0s, Lambda, AntiLambda have been measured. Mean multiplicities are reported as a function of the event kinematic variables Enu, W2 and Q2 as well as of the variables describing particle behaviour within a hadronic jet: xF, z and pT2. Decays of resonances and heavy hyperons with identified K0s and Lambda in the final state have been analyzed. Clear signals corresponding to K*+-, Sigma*+-, Xi- and Sigma0 have been observed.
Measured yields of the neutral strange particles measured in this analysis.The second line (marked *) is a recalculation taking into account contributions from both primary and secondary V0. The values for K0 are the K0S rates multipl ied by 2.
Measured yields as a function of E, the neutrino energy.
Measured yields as a function of W**2.
The formation and subsequent decay of nuclei excited via the annihilation of 1.22-GeV antiprotons have been investigated at the low energy antiproton ring (LEAR). Both neutrons and charged products, from protons up to fission fragments and heavy residues, were detected over a solid angle of 4π by means of the Berlin neutron ball (BNB) and the Berlin silicon ball (BSiB), respectively. All events associated with an inelasticity greater than 10 MeV were recorded, a condition fulfilled for 100% of the annihilation events. The distributions of excitation energy (E*) of the transient hot nuclei have been investigated for a large range of target nuclei, E* being determined event by event from the total multiplicity of light particles. The average excitation energies are about twice as large as for annihilations at rest, and range from 2.5 MeV/nucleon for the Cu target to 1.5 MeV/nucleon for the U target, in good agreement with the predictions of an intranuclear-cascade model. The distributions extend to E*>8 MeV/nucleon for Cu and E*>5 MeV/nucleon for Au, with cross sections exceeding 1% of σreac. Thanks to the capability of determining E* for all events, largely irrespective of their mass partitions, the probabilities of the different decay channels at play could be estimated as a function of E*. The data show the prevalence of fission and evaporation up to E*=4–5 MeV/nucleon for Au and U. The fission probability Pfis was measured for the first time over the full range of E*. The reproduction of the data by statistical models is reasonable, provided that the ratio af/an is adjusted for the different targets and a transient time shorter than 1×10−21 s is considered. The experiment has allowed the fission probability to be investigated as functions of the associated neutron and light-charged particle multiplicities. The intermediate-mass fragment multiplicities rise smoothly with E* up to about 1 unit at E*=1 GeV for Au and U, with no indication of significant contribution from another process than evaporation. Heavy residues have been measured quite abundantly at the highest E*, with most of their kinetic energy arising from the recoil effects in the evaporation stage. Overall, the data allow a coherent picture to be established, consistent with the hot nucleus retaining conventional decay properties.
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Charged particle multiplicities from high multiplicity central interactions of 158 GeV/nucleon Pb ions with Pb target nuclei have been measured in the central and far forward projectile spectator regions using emulsion chambers. Multiplicities are significantly lower than predicted by Monte Carlo simulations. We examine the shape of the pseudorapidity distribution and its dependence on centrality in detail.
Q(NAME=B) parameter is the total sum of the individual charges of the projectile fragments.
We report the first precision measurements of the scaled momentum, the charge multiplicity, and the thrust of hadronic jets in the Breit frame in Deep Inelastic Scattering ν μ N and ν ̄ μ N charged current events over the Q 2 range from 1 to 100 GeV 2 . The neutrino data, obtained in the NOMAD experiment at the CERN SPS, extend the Q 2 -evolution of these parameters by two orders of magnitude, and with commensurate precision, when compared to those reported by the ep and e + e − experiments.
Average neutrino energy. Peak postion of distribution on log(1/z) is presented.
Using data from the Fermilab fixed target experiment E665, general properties of forward produced charged hadrons in μp interactions at a primary muon energy of 470 GeV are investigated. The normalized inclusive singleparticle distributions for Feynman-x D(xF ) and for the transverse momentum D(p2t , xF ) are measured as a function of W and Q2. The dependence of the average transverse momentum squared 〈p2t〉 on xF , W and Q2 is studied. The increasing contribution from diffractive production as Q2 decreases leads to a reduction of the average charged hadron multiplicities at low (positive) xF and an enhancement at large xF , for Q2 ≲ 10 GeV2. It also reduces 〈p2t〉 for Q2 ≲ 5 GeV2 and 0.4 ≲ xF < 1.0.
Normalised inclusive single particle distributions of charged hadrons for all events in W intervals. Additional systematic uncertainty of 4 PCT.
Normalised inclusive single particle distributions of charged hadrons for all events in Q**2 intervals. Additional systematic uncertainty of 4 PCT.
Normalised inclusive single particle distributions of charged hadrons for all events in X (Bjorken) intervals. Additional systematic uncertainty of 4 PCT.
The Krakow-Louisiana-Minnesota-Moscow Collaboration (KLMM) has exposed a set of emulsion chambers with lead targets to a 158 GeV/c per nucleon beam of Pb208 nuclei, and we report the initial analysis of 40 high-multiplicity Pb-Pb collisions. To test the validity of the superposition model of nucleus-nucleus interactions in this new regime, we compare the shapes of the pseudorapidity distributions with FRITIOF Monte Carlo model calculations, and find close agreement for even the most central events. We characterize head-on collisions as having a mean multiplicity of 1550±120 and a peak pseudorapidity density of 390±30. These estimates are significantly lower than our FRITIOF calculations. © 1996 The American Physical Society.
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Simultaneous measurements of inclusive energy spectra and multiplicities of π±, K±, n, p, d, and t following antiproton annihilation on nuclei over a wide energy range and in the case of neutrons down to the evaporative part of the spectra are reported. Thirteen targets in the mass range of A=12–238 were used in a target mass dependent investigation of the fast stage of the antiproton-nucleus interaction. The deduced transferred, preequilibrium and equilibrium excitation energies agree very well with the dynamical picture drawn by the intranuclear cascade model (INC). Ratios of directly emitted neutrons to protons have been determined to be about twice the N/Z ratio in the target nucleus nearly independently of its mass. These unexpected values for this new sensitive observable are not completely understood in the standard framework of INC. Possible effects of isospin and nucleon densities as well as further schemes beyond the INC are discussed.
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The production ofK0, Λ and\(\bar \Lambda \) particles is studied in the E665 muon-nucleon experiment at Fermilab. The average multiplicities and squared transverse momenta are measured as a function ofxF andW2. Most features of the data can be well described by the Lund model. Within this model, the data on the K0/π± ratios and on the averageK0 multiplicity in the forward region favor a strangeness suppression factors/u in the fragmentation process near 0.20. Clear evidence for QCD effects is seen in the average squared transverse momentum ofK0 and Λ particles.
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Results on the production of charged hadrons in muon-deuteron and muon-xenon interactions are presented. The data were taken with the E665 spectrometer, which was exposed to the 490 GeV muon beam of the Tevatron at Fermilab. The use of a streamer chamber as vertex detector provides nearly 4π acceptance for charged particles. The μD data are compared with the μXe data in terms of multiplicity distributions, average multiplicities, forward-backward multiplicity correlations, rapidity and transverse momentum distributions and of two-particle rapidity correlations of charged hadrons. The data cover a range of invariant hadronic massesW from 8 to 30 GeV.
Results of negative binomial function fit to the multiplicity distribution of charged hadrons in muon-deuteron scattering. DISPERSION = SQRT(1/MULT + 1/K) is this dispersion of the scaled multiplicity Z = N/MULT.
Results of negative binomial function fit to the multiplicity distribution of charged hadrons in muon-xenon scattering. DISPERSION = SQRT(1/MULT + 1/K) is this dispersion of the scaled multiplicity Z = N/MULT.
Results of negative binomial fits to charged hadron multiplicity distributions in muon-deuteron interactions for backward and forward hemispheres of the hadronic cm.
The degree of excitation of the emulsion target nuclei due to nuclear interactions of oxygen and sulfur projectiles at 200 GeV/nucleon incident energy has been investigated. Using the plausible assumption that the numberNb of slow particles emitted from the struck target nucleus can be interpreted as a measure of the temperatureT of the residual nucleus, we have found that there exists a critical temperatureTc of the excited target nucleus. For Ag and Br target nuclei this temperature corresponds to <Nb>≌12 and it is attained when the impact parameters are less than about 4 fm.
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Experimental data on multiplicities and angular distributions of heavy ionizing and shower particles in inelastic interactions of 350 GeV Σ− hyperons in nuclear emulsion are presented. The data are compared with the results of other experiments on proton and pion interactions in emulsion at energies of 60-800 GeV. We observe no significant differences in the global characteristics of strange hyperon interactions relative to nonstrange baryon interactions at equivalent energies, other than those attributable to the differing cross sections.
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This paper presents and contrasts features of the inelastic nuclear reactions of 200 GeV/nucleon 16 O and 32 S ions with emulsion nuclei. Both the multiplicities of shower particles and the extent of target fragmentation have been studied for varying degress of disruption of the projectile nuclei. The results may be interpreted within a simple geometrical model. In particular the rapidity distributions of those events which exhibit complete projectile break-up without any overt sign of low-energy target fragmentation have been determined. The interaction of secondary projectile fragments of charge two or more issuing from oxygen interactions were also studied and the mean free paths in emulsion of the primary 16 O and 32 S ions and all such fragments have been compared to those predicted by a simple Glauber model.
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Data on multiplicities of charged particles produced in proton-nucleus and nucleus-nucleus collisions at 200 GeV per nucleon are presented. It is shown that the mean multiplicity of negative particles is proportional to the mean number of nucleons participating in the collision both for nucleus-nucleus and proton-nucleus collisions. The apparent consistency of pion multiplicity data with the assumption of an incoherent superposition of nucleon-nucleon collisions is critically discussed.
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The production of the meson resonances ϱ(770) (all three charge states), η(550), ω(783) andf2(1270) in\(\bar v\) Ne and ν Ne charged current interactions is investigated in a bubble chamber experiment with BEBC at CERN. Except for thef2, the main features of resonance production are reasonably well described by the Lund model, although the average resonance multiplicities are overestimated by the model by (67±30)%. The average multiplicities of all resonances, including thef2, are well reproduced by a semiempirical model, whose parameters were determined from hadron interaction data.
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Scaled factorial moments, corrected for the shape of the single-particle pseudorapidity distribution, are analyzed in pseudorapidity and in two-dimensional (pseudorapidity and azimuth angle) space. An intermittent, power-law growth of the moments with decreasing bin size is found, with two-dimensional analysis revealing a much stronger effect than for one-dimensional for nucleus-nucleus data. The intermittent patterns are more evident for proton-nucleus than for nucleus-nucleus collisions, with the heaviest nucleus, S32, showing the weakest effect.
SEMICENTRAL EVENTS.
Multiplicity distributions, observed inK+ interactions with Al and Au nuclei at 250 GeV/c incident momentum are presented. They are analyzed in the framework of multiple collisions of the incident particle inside a nucleus. The probability distribution of the number of grey tracks is well described by the model of Andersson et al., if a negative binomial distribution is assumed for the distribution of the number of grey protons produced per elementary collision instead of the usual geometrical distribution. The analysis of the average and dispersion of the charge multiplicity distribution supports the validity of the multiple collision model, including results on correlations between forward and backward multiplicities.
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206 EVENTS.
206 EVENTS.
4000 EVENTS.
Central collisions of O16 nuclei with the Ag107 and Br80 nuclei in nuclear emulsion at 14.6, 60, and 200 GeV/nucleon are compared with proton-emulsion data at equivalent energies. The multiplicities of produced charged secondaries are consistent with the predictions of superposition models. At 200 GeV/nucleon the central particle pseudorapidity density is 58±2 for those events with multiplicities exceeding 200 particles.
Nucleus is average nucleus of BR-2 emulsion.
Nucleus is average nucleus of BR-2 emulsion.
Nucleus is average AG107/BR80 nucleus of BR-2 emulsion.
Theπ0 andη0 production is studied inπ−p interactions at 360 GeV/c. The cross section forπ0 production in the forward hemisphere (X>0) isσ(π0)=(49.7 ± 1.0 ± 1.1) mb and for η withX>0.1,Nch>2,σ(η0)=(3.1 ± 0.5) mb. The ratio of theπ0 toη0 cross section forX>0.1,Nch>2 isσ(π0)/σ(η0). Results on FeynmanX andpT distributions are presented. The data were obtained using the European Hybrid Spectrometer EHS and the bubble chamber LEBC at CERN.
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Results are reported concerning the charged-particle multiplicity distribution obtained in an exposure of the high-resolution hydrogen bubble chamber LEBC to a beam of 800 GeV protons at the Fermilab MPS. This is the first time that such data have been available at this energy. The distribution of the number n ch of charged particles produced in inelastic interactions obeys KNO-scaling. The average multiplicity is 〈 n ch 〉 = 10.26±0.15. For n ch ⩾8 the data can be well fitted to a negative binomial. The difference between the overall experimental multiplicity distribution and that resulting from the latter fit is in agreement with the contribution expected from diffractive processes.
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NUCLEUS IS C6J.
NUCLEUS IS C6J.
NUCLEUS IS C6J.
Measurements are presented of the variation with Q 2 (scaling violation) of the hadron multiplicity in deep inelastic muon-proton scattering. An increase in the average multiplicity of both the charged hadrons and K 0 mesons is observed with increasing Q 2 or x Bj for fixed centre-of-mass energy W . The study of the shape of the effective fragmentation function D h ( z , W , Q 2 ) shows that the increase of the particle yield with Q 2 takes place for low z particles. The variation of the hadron distributions with Q 2 is also studied in the current fragmentation region where a decrease in multiplicity is observed. Such effects are expected from QCD.
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Properties of the hadron multiplicity distributions in 280 GeV/c μ<sup loc="post">+</sup>p interactions have been investigated. The c.m. energy dependence in the range from 4 to 20 GeV of the total charged multiplicities are presented. No variation faster than logarithmic is seen in the energy range of this experiment. Comparison with νp and <math altimg="si1.gif"><ovl type="bar" style="s">ν</ovl><rm>p</rm></math> data at lower energy has been made and shows good agreement between μ<sup loc="post">+</sup>p and <math altimg="si1.gif"><ovl type="bar" style="s">ν</ovl><rm>p</rm></math> total charged multiplicities. It has been found that the average forward multiplicity (charged hadrons with xF > 0) exceeds the average backward multiplicity (charged hadrons with xF < 0) in the whole energy range and presents a different energy variation. The average forward multiplicity has been compared to e<sup loc="post">+</sup>e<sup loc="post">−</sup> data and shows a similar dependence on energy. Little correlation was observed between the forward and backward multiplicities indicating that the current and target regions fragment almost independently.
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Axis error includes +- 0.0/0.0 contribution (?////).
Axis error includes +- 0.0/0.0 contribution (?////).
Axis error includes +- 0.0/0.0 contribution (?////).
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