K. H. Khan

STUDY OF SOME CHARACTERISTICS OF PROTONS USING INTERACTIONS OF LIGHT NUCLEI

Behavior of some average characteristics of protons are studied in protons and deuterons induced interactions with carbon nuclei at 4.2 A GeV/c. The emitted particles are divided into two groups depending on their polar angle in the lab. frame using half angle technique. Results of the experimental data are compared with Dubna version of cascade model. Analysis of the results show that the inner cone protons are leading particles.

The nuclear transparency effect of π−-mesons in p+12C- and d+12C-interactions at 4.2A GeV/c

The use of the nuclear transparency effect of π−-mesons in a proton and deuteron-induced interactions with carbon nuclei at 4.2A GeV/c, to obtain information on the properties of nuclear matter, is presented in this work. The half angle (θ1/2) technique is used to extract information on the nuclear transparency effect. θ1/2 divides the multiplicity of charged particles into two equal parts depending on their polar angle in the laboratory frame in pp interactions. Particles with an angle smaller than (incone particles) and greater than (outcone particles) θ1/2 are considered separately. The average values of multiplicity, momentum and transverse momentum of the π−-mesons are analyzed as a function of a number of identified protons in an event. We observed evidences in the data which could be considered as the transparency effect. For quantitative analysis, the results are compared with the cascade model. The observed effects are categorized into leading effect transparency and medium effect transparency. The transparency in the latter case could be the reason for the collective interactions of grouped nucleons with the incident particles.

Average characteristics of π−-mesons in HeC and CC interactions at high energies

The study of average characteristics of π−-mesons in Helium–Carbon and Carbon–Carbon interactions at 4.2A GeV/c is presented. The average values of multiplicity, momentum and transverse momentum of π−-mesons are analyzed as a function of the number of identified protons in an event. The latter is used to fix the centrality of collisions. The results are compared with Cascade model and modified Fritiof model. Some deviations of experimental data are observed than the models, which could be connected to collective interaction of inner nucleus nucleons.

Study of the behavior of the nuclear modification factor in freeze-out state

One of the latest trends in the advancement of experimental high-energy physics is to identify the quark gluon plasma (QGP) predicted qualitatively by quantum chromodynamics (QCD). We discuss whether nuclear transparency effect which is considered an important phenomenon, connected with dynamics of hadron-nuclear and nuclear-nuclear interactions could reflect some particular properties of the medium. FASTMC is used for Au-Au collision at RHIC energies. Critical change in the transparency is considered a signal on the appearance of new phases of strongly interacting matter and the QGP.

Analysis of shower particle pseudorapidity spectra in interactions of relativistic Au and Pb ions with emulsion nuclei

The pseudorapidity spectra of fast particles (with β > 0.7) produced in Au (at 11.6 A GeV) and Pb (at 158 A GeV) induced collisions with emulsion (Em) nuclei contain some visual plateaus and shoulders. The plateau is wider for Pb+Em reactions compared with the Au+Em ones. The existence of a plateau is expected for parton models. The Fourier transformation and maximum entropy methods were used to get additional information about the plateaus. The dependence of the plateaus on the centrality of the collisions was also studied using the number of g-particles to fix centrality. It shows that the maximum entropy method could confirm the existence of the plateau and the shoulder on distributions.

Search for a signal on QCD critical point in central nucleusnucleus collisions

We discuss that the QCD critical point could appear in central collisions in percolation cluster. We suggest to use the effects of nuclear transparency and that of the light nuclear production to identify the critical point.

SOME PROPERTIES OF THE CENTRAL π--MESON CARBON INTERACTIONS AT 40 GeV/c

We discuss some properties of the central π--meson carbon reactions at 40 GeV/c. While these results were obtained many years ago they have not been explained completely. We attempt to interpret following: results regime change on the behavior of some characteristics of the events as a function of the centrality; anomaly peak on the angular distributions of the slow protons emitted in these reactions; charge asymmetry on the π--mesons production in the back hemisphere in lcs. Understanding of the results could help to explain the new ones coming from the modern central experiments at high and ultrarelativistic energies.

Effect of the jet production on pseudorapidity, transverse momentum and transverse mass distributions of charged particles produced in pp-collisions at Tevatron energy*

We investigate the effects of jet production on the following parameters: pseudorapidity, transverse momentum and transverse mass distributions of secondary charged particles produced in pp-collisions at 1.8 TeV, using the HIJING code. These distributions are analyzed for the whole range and for six selected regions of the polar angle as a function of the different number of jets. The obtained simulation results for these parameters are interpreted and discussed in connection to the increase observed in the multiplicity of secondary charged particles as a result of its multi-jet dependence, and are also discussed in comparison with the experimental results from the CDF Collaboration.

Light nuclei formation in 12CC collisions at 4.2A GeV/c

Some properties: average multiplicity, average momentum and average transverse momentum of light nuclei (without identification), produced in 12CC collisions at 4.2A GeV/c are studied as a function of centrality. An unexpected change in the behavior of these properties is observed within the same region of centrality, where the multiplicity of the produced light nuclei is increased. These measurements are compared with models, Cascade and Fritiof predictions, which fail to account for the observed effect. It is suggested that the inclusion of nuclear coalescence effect may explain the difference between the measurements and the predictions.

On influences of the jet production to charged particles multiplicity distribution in pp-collisions at Tevatron energies

Effect of the jet production on the multiplicity distribution (MD) of secondary charged particles produced in pp-collisions at 1.8 TeV is studied using the HIJING code. The charged particles MDs for a whole polar angle range and for six polar angular regions as a function of different number of jets were analyzed. The obtained simulation results were compared with experimental MDs coming from the Tevatron and SPS experiments. The increasing behavior of multiplicity of the secondary charged particles influenced by multi-jet events is discussed.