共查询到20条相似文献,搜索用时 31 毫秒
1.
T. Alber et al. 《The European Physical Journal C - Particles and Fields》1998,2(4):643-659
The transverse momentum and rapidity distributions of net protons and negatively charged hadrons have been measured for minimum
bias proton–nucleus and deuteron–gold interactions, as well as central oxygen–gold and sulphur–nucleus collisions at 200 GeV
per nucleon. The rapidity density of net protons at midrapidity in central nucleus–nucleus collisions increases both with
target mass for sulphur projectiles and with the projectile mass for a gold target. The
shape of the rapidity distributions of net protons forward of midrapidity for d+Au and central S+Au collisions is similar.
The average rapidity loss is larger than 2 units of rapidity for reactions with the gold target. The transverse momentum spectra
of net protons for all reactions can be described by a thermal distribution with ‘temperatures’ between MeV (p+S interactions) and MeV (central S+Au collisions). The multiplicity of negatively charged hadrons increases with the mass of the colliding system.
The shape of the transverse momentum spectra of negatively charged hadrons changes from minimum bias p+p and p+S interactions
to p+Au and central nucleus-nucleus collisions. The mean transverse momentum is almost constant in the vicinity of midrapidity
and shows little variation with the target and projectile masses. The average number of produced negatively charged hadrons
per participant baryon increases slightly from p+p, p+A to central S+S,Ag collisions.
Received: 28 October 1997 / Published online: 10 March 1998 相似文献
2.
The multiplicity fluctuations of the produced pions were studied using scaled variance method in 16O–AgBr interactions at 2.1 AGeV, 24Mg–AgBr interactions at 4.5 AGeV, 12C–AgBr interactions at 4.5 AGeV, 16O–AgBr interactions at 60 AGeV and 32S–AgBr interactions at 200 AGeV at two different binning conditions. In the first binning condition, the rapidity interval
was varied in steps of one centring about the central rapidity until it reached 14. In the second case, the rapidity interval
was increased in steps of 1.6 up to 14.4. Multiplicity distributions and their scaled variances were presented as a function
of the dependence on the rapidity width for both the binning conditions. Multiplicity fluctuations were found to increase
with the increase of rapidity interval and later found to saturate at larger rapidity window for all the interactions and
in both the binning conditions. Multiplicity fluctuations were found to increase with the energy of the projectile beam. The
values of the scaled variances were found to be greater than one in all the cases in both the binning conditions indicating
the presence of correlation during the multiparticle production process in high-energy nucleus–nucleus interactions. Experimental
results were compared with the results obtained from the Monte Carlo simulated events for all the interactions. The Monte
Carlo simulated data showed very small values of scaled variance suggesting very small fluctuations for the simulated events.
Experimental results obtained from 16O–AgBr interactions at 60 AGeV and 32S–AgBr interactions at 200 AGeV were compared with the events generated by Lund Monte Carlo code (FRITIOF model). FRITIOF
model failed to explain the multiplicity fluctuations of pions emitted from 16O–AgBr interactions at 60 AGeV for both the binning conditions. However, the experimental data agreed well with the FRITIOF
model for 32S–AgBr interactions at 200 AGeV. 相似文献
3.
A. Akindinov A. Alici P. Antonioli S. Arcelli M. Basile G. Cara Romeo M. Chumakov L. Cifarelli F. Cindolo A. De Caro D. De Gruttola S. De Pasquale M. Fusco Girard C. Guarnaccia D. Hatzifotiadou H.T. Jung W.W. Jung D.W. Kim H.N. Kim J.S. Kim S. Kiselev G. Laurenti K. Lee S.C. Lee E. Lioublev M.L. Luvisetto A. Margotti A. Martemiyanov R. Nania F. Noferini P. Pagano A. Pesci R. Preghenella G. Russo E. Scapparone G. Scioli R. Silvestri Y. Sun I. Vetlitskiy K. Voloshin L. Vorobiev M.C.S. Williams B. Zagreev C. Zampolli A. Zichichi 《The European Physical Journal C - Particles and Fields》2007,50(2):341-352
In this work we explore the possibility to perform “effective energy” studies in very high energy collisions at the CERN large
hadron collider (LHC). In particular, we focus on the possibility to measure in pp collisions the average charged multiplicity
as a function of the effective energy with the ALICE experiment, using its capability to measure the energy of the leading
baryons with the zero degree calorimeters. Analyses of this kind have been done at lower centre-of-mass energies and have
shown that, once the appropriate kinematic variables are chosen, particle production is characterized by universal properties:
no matter the nature of the interacting particles, the final states have identical features. Assuming that this universality
picture can be extended to ion–ion collisions, as suggested by recent results from RHIC experiments, a novel approach based on the scaling hypothesis for limiting
fragmentation has been used to derive the expected charged event multiplicity in AA interactions at LHC. This leads to scenarios
where the multiplicity is significantly lower compared to most of the predictions from the models currently used to describe
high energy AA collisions. A mean charged multiplicity of about 1000–2000 per rapidity unit (at η∼0) is expected for the most
central Pb–Pb collisions at .
In memory of A. Smirnitskiy 相似文献
4.
Recently the WA97 Collaboration has measured , , , and negative particle yields and transverse mass spectra at central rapidity in Pb–Pb and p–Pb collisions at 158 A GeV/c.
These results are compared with the predictions of two of the most widely used event generators for heavy-ion collisions:
VENUS 4.12 and RQMD 2.3. Both models predict that enhancements increase with the strangeness content of the particle. They
fail, however, to reproduce completely the measured values of yields at central rapidity. In particular, for multistrange
particles, VENUS fails to reproduce both the p–Pb and the Pb–Pb data, while RQMD works for p–Pb collisions but seems to be
unable to reproduce the data in Pb–Pb collisions. Moreover, the predicted behavior for strangeness production as a function of the centrality of
the collision appears to be different from the observed behavior.
Received: 29 April 1999 / Published online: 14 October 1999 相似文献
5.
Edward K. G. Sarkisyan Alexander S. Sakharov 《The European Physical Journal C - Particles and Fields》2010,70(3):533-541
The energy-dependence of charged particle mean multiplicity and pseudorapidity density at midrapidity measured in nucleus–nucleus
and (anti)proton–proton collisions are studied in the entire available energy range. The study is performed using a model,
which considers the multiparticle production process according to the dissipating energy of the participants and their types,
namely a combination of the constituent quark picture together with Landau relativistic hydrodynamics. The model reveals interrelations
between the variables under study measured in nucleus–nucleus and nucleon–nucleon collisions. Measurements in nuclear reactions
are shown to be well reproduced by the measurements in pp/[`(p)]p{\bar{\mathrm{p}}}{\mathrm{p}} interactions and the corresponding fits are presented. Different observations in other types of collisions are discussed
in the framework of the proposed model. Predictions are made for measurements at the forthcoming LHC energies. 相似文献
6.
Abdel Nasser Tawfik Magda Abdel Wahab Hayam Yassin Hadeer M. Nasr El Din 《Journal of Experimental and Theoretical Physics》2020,130(4):506-516
Based on statistical thermal approaches, the transverse momentum distribution of the well-identified produced particles, π+, π–, K+, K–, p, and $$\bar {p}$$, is studied. We aim at introducing a novel almost entirely empirical estimation for the inclusive chemical potential μ. From the partition function of a grand-canonical ensemble, we propose a generic expression for the dependence of μ on the rapidity y. Then, by fitting this expression with the experimental results of the most central p⊥ and d2N/2πp⊥dp⊥dy, at 7.7, 11.5, 19.6, 27, 39, 130, 200 GeV, we introduce a generic expression for the rapidity dependence of for all particle yields, at different energies, μ = a + by2. The resulting energy dependence reads $$\sqrt {{{s}_{{{\text{NN}}}}}} $$ = c[(μ – a)/b]d/2. As a validation test, we show that the proposed approach reproduces excellently the rapidity spectra of various particle yields measured, at different energies. 相似文献
7.
E. Kornas 《The European Physical Journal C - Particles and Fields》2007,49(1):293-296
Recent results of the NA49 collaboration on the production of p and p̄ at midrapidity in central Pb+Pb collisions in the beam
energy range 20–158 A GeV are presented. The preliminary results for the rapidity distributions of p and p̄ at 40 A GeV
are also discussed.
PACS 25.75.Dw 相似文献
8.
J.W. Lämsä L.R. Fortney A.T. Goshaw J.S. Loos W.J. Robertson W.D. Walker W.D. Shephard J.M. Bishop N.N. Biswas N.M. Cason V.P. Kenney B.M. Schwarzschild G. Hartner G. Levman V.A. Sreedhar T.S. Yoon P.M. Patel 《Nuclear Physics B》1978,135(2):258-264
A study of multiparticle rapidity clustering is made using a generalized rapidity-gap method. The data for events with ?6 charged particles are compared to what would be expected from uncorrelated particle production. We find clear evidence for cluster production. The data are consistent with ~ 20% of all charged particles being produced in clusters of two charged particles; clusters of higher multiplicity are not required. 相似文献
9.
A. I. Golokhvastov 《Physics of Atomic Nuclei》2004,67(12):2227-2244
It is shown that experimental data on the multiparticle production of negatively charged pions in proton-proton interactions at \(\sqrt s \leqslant 30 GeV\) do not involve significant indications of the existence of anycorrela tions between negatively charged pions, apart from those that are associated with momentum conservation and with interference. The multiplicity distributions in rapidity intervals, forward-backward correlations, and two-particle rapidity and transverse-momentum correlations do not contradict the independent production of negatively charged pions. No constraints on the multiplicity distributions of product particles follow from their independent production. 相似文献
10.
S.P.K. Tavernier 《Nuclear Physics B》1976,105(2):241-252
It is shown that a constituent picture of hadrons, with no other fundamental assumption than that only one constituent in each hadron interacts with one constituent in the other hadron, explains several features of particle production in high-energy collisions. We obtain KNO scaling of the particle multiplicity, a neutral for multiplicity for fixed charged multiplicity which is independent of the energy, and a rapidity distribution of the central fireball which depends on n/〈n〉 only. Numerical applications show that the quark momentum distribution which reproduces the experimental data in strong interactions is very similar to the valence quark momentum distribution derived from deep inelastic scattering experiments. 相似文献
11.
Marek Gaździcki Mark I. Gorenstein Stanislaw Mrówczyński 《The European Physical Journal C - Particles and Fields》1998,5(1):129-133
The pion multiplicity per participating nucleon in central nucleus–nucleus collisions at the energies 2–15 AGeV is significantly smaller than in nucleon–nucleon interactions at the same collision energy. This effect of pion suppression is argued to appear due to the evolution of the system produced at the early stage of heavy–ion collisions towards a local
thermodynamic equilibrium and further isentropic expansion.
Received: 21 July 1997 / Revised version: 12 November 1997 / Published online: 26 February 1998 相似文献
12.
W. Bell K. Braune G. Claesson D. Drijard M. A. Faessler H. G. Fischer H. Frehse R. W. Frey S. Garpman W. Geist C. Gruhn P. Hanke M. Heiden W. Herr P. G. Innocenti T. J. Ketel E. E. Kluge I. Lund G. Mornacchi T. Nakada I. Otterlund B. Povh A. Putzer B. Rensch E. Stenlund T. J. M. Symons R. Szwed O. Ullaland M. Wunsch CERN-Heidelberg-Lund Collaboration 《Zeitschrift fur Physik C Particles and Fields》1984,22(2):109-118
Two-particle rapidity correlations have been studied for αα, αp, andp p interactions at the CERN ISR using the Split-Field Magnet (SFM) detector. In order to isolate the true two-particle correlations, the analysis was performed at fixed charged multiplicity. In the framework of a simple cluster model, it is found that cluster widths as well as cluster multiplicities are the same for αα, αp, andp p interactions, and both decrease with increasing charged multiplicity. 相似文献
13.
《The European Physical Journal C - Particles and Fields》2007,52(3):531-542
The inclusive production cross sections of the charmed mesons D0,D+,Ds
+ and D*+ have been measured in interactions of 920 GeV protons on C, Ti, and W targets with the HERA-B detector at the HERA storage
ring. Differential cross sections as a function of transverse momentum and Feynman’s x variable are given for the central
rapidity region and for transverse momenta up to pT=3.5 GeV/c. The atomic mass number dependence and the leading to non-leading particle production asymmetries are presented as well.
PACS 13.85.Ni; 24.85.+p; 13.20.Fc 相似文献
14.
S K Badyal V K Gupta G L Kaul Balvinder Kour Y Prakash N K Rao S K Sharma Gian Singh 《Pramana》1980,14(4):303-313
Characteristics of the inelastic interactions of 9.38 GeV/c deuterons with nuclear emulsion nuclei have been studied. These
have been compared with nucleon-nucleus interactions at a corresponding momentum. The probability of nucleon stripping in
deuteron-nucleus interactions has been observed to be 0.5. The charged particle multiplicity in deuteron-nucleus interactions
exhibitA-dependence of the typeA
α with α=0.08. The experimental data disagree with KNO scaling. 相似文献
15.
I. V. Ajinenko Yu. A. Belokopytov H. Bialkowska H. Boettcher F. Botterweck M. Charlet P. V. Chliapnikov F. Crijns A. De Roeck D. A. De Wolf K. Dziunikowska A. M. F. Endler A. Eskreys Z. C. Garutchava Y. A. Golubkov G. R. Gulkanyan P. van Hal R. Sh. Hakobyan T. Haupt W. Kittel D. Kisielewska B. B. Levchenko B. Machowski F. Meijers A. B. Micha?owska V. I. Nikolaenko K. Olkiewicz R. P?ll?nen V. M. Ronjin A. M. Rybin H. M. T. Saarikko L. Scholten L. N. Smirnova O. G. Tchikilev V. A. Uvarov F. Verbeure R. Wischnewski EHS-NA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1990,46(4):569-582
The negative binomial distribution (NBD) is fitted to all charged and to negative particle multiplicity distributions in restricted rapidity intervals, both in the forward and backward c.m. hemispheres of positive meson interactions on Al and Au nuclei. For negative particle multiplicity distributions, the NBD parameters are also determined as a function ofn g, the number of grey tracks, corresponding to varying number of intranuclear collisions. The data are interpreted in terms of the clan picture of Giovannini and Van Hove and compared to the MCMHA and Fritiof models. Both models reproduce quite well the global multiplicity distributions, but not when sub-samples are considered with fixed number of grey tracks. Regularities are better visible on the parton than on the particle level. 相似文献
16.
《The European Physical Journal C - Particles and Fields》2007,51(4):775-785
The CHORUS experiment, designed to search for νμ→ντ oscillations, consists of a nuclear emulsion target and electronic detectors. In this paper, results on the production of
charged particles in a small sample of charged-current neutrino– and anti-neutrino–nucleus interactions at high energy are
presented. For each event, the emission angle and the ionization features of the charged particles produced in the interaction
are recorded, while the standard kinematic variables are reconstructed using the electronic detectors. The average multiplicities
for charged tracks, the pseudo-rapidity distributions, the dispersion in the multiplicity of charged particles and the KNO
scaling are studied in different kinematical regions. A study of quasi-elastic topologies performed for the first time in
nuclear emulsions is also reported. The results are presented in a form suitable for use in the validation of Monte Carlo
generators of neutrino–nucleus interactions. 相似文献
17.
J. B?chler J. Bartke H. Bia?kowska R. Bock R. Brockmann P. Buncic S. I. Chase I. Derado V. Eckardt J. Eschke et al. 《Zeitschrift fur Physik C Particles and Fields》1992,56(3):347-354
Multiplicity distributions and their second moments fornegatively charged particles produced in32S-S central and minimum bias interactions at 200A GeV are studied in various rapidity intervals. Fritiof and Venus models mostly describe the dependence of second moments on rapidity intervals in minimum bias interactions, but not in central collisions. For central collisions the behaviour of second moments might indicate enhanced multiplicity fluctuations. 相似文献
18.
Back BB Baker MD Ballintijn M Barton DS Becker B Betts RR Bickley AA Bindel R Busza W Carroll A Decowski MP García E Gburek T George N Gulbrandsen K Gushue S Halliwell C Hamblen J Harrington AS Henderson C Hofman DJ Hollis RS Hołyński R Holzman B Iordanova A Johnson E Kane JL Khan N Kulinich P Kuo CM Lee JW Lin WT Manly S Mignerey AC Nouicer R Olszewski A Pak R Park IC Pernegger H Reed C Roland C Roland G Sagerer J Sarin P Sedykh I Skulski W Smith CE Steinberg P Stephans GS Sukhanov A Tonjes MB 《Physical review letters》2004,93(8):082301
The measured pseudorapidity distribution of primary charged particles in minimum-bias d+Au collisions at sqrt[s(NN)]=200 GeV is presented for the first time. This distribution falls off less rapidly in the gold direction as compared to the deuteron direction. The average value of the charged particle pseudorapidity density at midrapidity is |eta|< or =0.6)=9.4+/-0.7(syst) and the integrated primary charged particle multiplicity in the measured region is 82+/-6(syst). Estimates of the total charged particle production, based on extrapolations outside the measured pseudorapidity region, are also presented. The pseudorapidity distribution, normalized to the number of participants in d+Au collisions, is compared to those of Au+Au and p+(-)p systems at the same energy. The d+Au distribution is also compared to the predictions of the parton saturation model, as well as microscopic models. 相似文献
19.
G. Abbiendi et al. 《The European Physical Journal C - Particles and Fields》2006,45(2):291-305
The effects of the final state interaction phenomenon known as colour reconnection are investigated at centre-of-mass energies
in the range
≃ 189–209 using the OPAL detector at LEP. Colour reconnection is expected to affect observables based on charged particles
in hadronic decays of . Measurements of inclusive charged particle multiplicities, and of their angular distribution with
respect to the four jet axes of the events, are used to test models of colour reconnection. The data are found to exclude
extreme scenarios of the Sj?strand-Khoze Type I () model and are compatible with other models, both with and without colour
reconnection effects. In the context of the model, the best agreement with data is obtained for a reconnection probability
of 37%. Assuming no colour reconnection, the charged particle multiplicity in hadronically decaying W bosons is measured to
be
=19.38±0.05(stat.)±0.08(syst.).
Arrival of the final proofs: 28 November 2005 相似文献
20.
M. I. Adamovich M. M. Aggarwal Y. A. Alexandrov N. P. Andreeva Z. V. Anson R. Arora F. A. Avetyan S. K. Badyal E. Basova K. B. Bhalla et al. 《Zeitschrift fur Physik C Particles and Fields》1992,56(4):509-520
The energy and centrality dependence of local particle pseudorapidity densities as well as validity of various parametrizations of the distributions are examined. The dispersion, , of the rapidity density distribution of produced particles varies slowly with centrality and is 0.80, 0.98, 1.21 and 1.41 for central interactions at 3.7, 14.6, 60 and 200A GeV incident energy, respectively, is found to be independent of the size of the interacting system at fixed energy. A novel way of representing the window dependence of the multiplicity as normalized variance versus inverse average multiplicity is outlined. 相似文献