PARTICLE AND FRAGMENT EMISSION IN VIOLENT RELATIVISTIC HEAVY-ION COLLISIONS: THE 4π-DETECTOR AT GSI, A NEW FACILITY FOR THIS INVESTIGATION

1992 ◽  
Vol 01 (04) ◽  
pp. 739-792 ◽  
Author(s):  
◽  
J. P. COFFIN
Keyword(s):  
Phase I ◽  
Heavy Ions ◽  
Charged Particles ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Accelerator Complex ◽  
Central Collisions ◽  
Ion Collisions ◽  
First Results ◽  
New Facility

By the end of 1989 a new accelerator complex, SIS/ESR, comprising a synchrotron and a storage ring for heavy-ions, came into operation at GSI (Darmstadt). To serve this facility, the construction of a detection ensemble devoted to the measurement of π, K, p, complex particles (Z ≤ 2) and fragments (Z > 2) operating in a near 4π geometry has been undertaken. Charged particles and fragments only are dealt with in this contribution. The main motivations of Physics which justify such an enterprise are exposed, then the part (Phase I) of the detector designed for particle and fragment detection, is described in some detail while the Phase II, not yet operational, is only touched upon. Some first results obtained from measurements relative to Au (150 A MeV ) + Au central collisions are presented and discussed.

scholarly journals Centrality, transverse momentum and collision energy dependence of the Tsallis parameters in relativistic heavy-ion collisions

2021 ◽  
Vol 136 (6) ◽  
Author(s):  
Rajendra Nath Patra ◽  
Bedangadas Mohanty ◽  
Tapan K. Nayak
Keyword(s):  
Transverse Momentum ◽  
Heavy Ion Collisions ◽  
Collision Energy ◽  
Charged Particles ◽  
Heavy Ion ◽  
High Energy ◽  
Relativistic Heavy Ion Collisions ◽  
Central Collisions ◽  
Ion Collisions ◽  
Tsallis Distribution

AbstractThe thermodynamic properties of matter created in high-energy heavy-ion collisions have been studied in the framework of the non-extensive Tsallis statistics. The transverse momentum ($$p_\mathrm{T}$$ p T ) spectra of identified charged particles (pions, kaons, protons) and all charged particles from the available experimental data of Au-Au collisions at the Relativistic Heavy Ion Collider (RHIC) energies and Pb-Pb collisions at the Large Hadron Collider (LHC) energies are fitted by the Tsallis distribution. The fit parameters, q and T, measure the degree of deviation from an equilibrium state and the effective temperature of the thermalized system, respectively. The $$p_\mathrm{T}$$ p T  spectra are well described by the Tsallis distribution function from peripheral to central collisions for the wide range of collision energies, from $$\sqrt{s_\mathrm{NN}}$$ s NN = 7.7 GeV to 5.02 TeV. The extracted Tsallis parameters are found to be dependent on the particle species, collision energy, centrality, and fitting ranges in $$p_\mathrm{T}$$ p T . For central collisions, both q and T depend strongly on the fit ranges in $$p_\mathrm{T}$$ p T . For most of the collision energies, q remains almost constant as a function of centrality, whereas T increases from peripheral to central collisions. For a given centrality, q systematically increases as a function of collision energy, whereas T has a decreasing trend. A profile plot of q and T with respect to collision energy and centrality shows an anti-correlation between the two parameters.

Transit Times in Lltra-Relativistic Heavy-Ion Collisions

1991 ◽  
Vol 46 (12) ◽  
pp. 1037-1042 ◽  
Author(s):  
G. Wolschin
Keyword(s):  
Heavy Ions ◽  
Heavy Ion Collisions ◽  
Hadron Collider ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Maximum Energy ◽  
Relativistic Heavy Ion Collisions ◽  
Ion Collisions ◽  
Transit Times ◽  
The Impact

Abstract Mean transit times in heavy-ion collisions are calculated as functions of the relativistic incident energy and the impact parameter. As a consequence of special relativity, they become constant in a central collision of O with Pb at T~0.15TeV. Together with a geometrical estimate of the maximum energy densities in the interaction region, it is argued that heavy ions in a large hadron collider may produce a quark-gluon plasma due to the plateau in the transit times at ultra-relativistic energies

PRODUCTION OF DILEPTONS BY BREMSSTRAHLUNG DURING THE STOPPING OF RELATIVISTIC HEAVY IONS

1989 ◽  
Vol 04 (16) ◽  
pp. 4221-4234 ◽  
Author(s):  
THOMAS LIPPERT ◽  
NORBERT GRÜN ◽  
WERNER SCHEID
Keyword(s):  
Probability Distributions ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Lepton Pairs ◽  
Differential Probability ◽  
First Order ◽  
Central Collisions ◽  
Ion Collisions ◽  
Muon Pairs ◽  
200 Gev

Lepton pairs are created by the bremsstrahlung during the stopping of nuclei in relativistic heavy ion collisions. The probability distribution for central collisions is derived in the first order perturbation theory. For the nuclear current density, a model is used which assumes point-like nuclear charges and a velocity of the nuclei parametrized with respect to the deceleration and transparency of the reaction. Differential probability distributions for muon pairs are calculated for central collisions of 238 U on 238 U at E lab = 200 GeV/nucleon .

PROTON PRODUCTION IN RELATIVISTIC HEAVY ION COLLISIONS: COMPARISON WITH A THERMODYNAMICAL MODEL

1989 ◽  
Vol 04 (14) ◽  
pp. 3689-3703 ◽  
Author(s):  
M.J. PARIZET ◽  
J.P. ALARD ◽  
A. RAHMANI ◽  
G. MONTAROU ◽  
J. AUGERAT ◽  
...  
Keyword(s):  
Cross Sections ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Laboratory System ◽  
Angular Range ◽  
Nuclear Collisions ◽  
Central Collisions ◽  
Ion Collisions ◽  
Proton Production ◽  
Thermodynamical Model

Experimental results concerning proton production in nuclear collisions, obtained at Saturne with the Diogene 4π facility, are compared with the predictions of a thermodynamical model, using collective velocity distributions combined with a statistical thermodynamics in local rest frames. Experimental differential cross sections for alpha + nucleus and Neon + nucleus central collisions at incident energies between 200 and 800 MeV per nucleon are well reproduced by the model, for an angular range 30–110 degrees in the laboratory system. Extracted values of the temperatures are compared with those given by other authors.

scholarly journals Heavy-ion Physics (ATLAS)

2018 ◽  
Vol 182 ◽  
pp. 02101
Author(s):  
Mariusz Przybycien
Keyword(s):  
Hadron Collider ◽  
Charged Particles ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Heavy Ion Physics ◽  
Atlas Experiment ◽  
Ion Collisions ◽  
Physics Program ◽  
Electromagnetic Processes ◽  
Peripheral Collisions

The ATLAS experiment at the Large Hadron Collider has undertaken a broad physics program to probe and characterize the hot nuclear matter created in relativistic heavy-ion collisions. This talk presents recent results on production of electroweak bosons and quarkonium, charged particles and jets, bulk particle collectivity and electromagnetic processes in ultra-peripheral collisions, from Pb+Pb and p+Pb systems.

scholarly journals Recent ATLAS measurements of azimuthal anisotropies in pp and p+Pb collisions

2018 ◽  
Vol 172 ◽  
pp. 05003
Author(s):  
Adam Trzupek
Keyword(s):  
Charged Particles ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Relativistic Heavy Ion Collisions ◽  
Heavy Flavor ◽  
Particle Correlations ◽  
Ion Collisions ◽  
Fitting Procedure ◽  
Cumulant Method ◽  
Flow Effects

The azimuthal anisotropies of particle yields observed in relativistic heavy-ion collisions are considered as an evidence of the formation on a deconfined Quark-Gluon Plasma produced in these collisions. Interestingly, recent measurements in pp and p+Pb systems from ATLAS and other experiments show similar features as those observed in A+A collisions, indicating the possibility of the production of such a deconfined medium in smaller collision systems. This report presents a summary of the recent ATLAS results on azimuthal anisotropies in pp collisions at 5.02 TeV and 13 TeV, p+Pb collisions at 5.02 TeV and 8.16 TeV as well as in peripheral 2.76 TeV Pb+Pb interactions. It includes measurements of two-particle correlations of charged particles as well as correlations of heavy flavor muons and charged particles in Δϕ and Δη, with a template fitting procedure used to subtract the dijet contributions. Additionally, measurements of cumulants of multi-particle correlations, cn{2-8} are presented. The two-particle correlations and cumulants confirm a presence of collective phenomena in these collision systems, but the results on four-particle cumulants for pp collisions do not demonstrate a similar collective behaviour. However, the cumulant measurements in small collision systems can be biased by non-flow correlations. A novel subevent cumulant method that suppresses the contribution of non-flow effects was proposed recently by ATLAS allowing to measure significant azimuthal anisotropies in both pp and p+Pb collisions.

CHARACTERISTICS OF CENTRAL AND MINIMUM-BIAS EVENTS IN ULTRA-RELATIVISTIC HEAVY-ION COLLISIONS

1990 ◽  
Vol 05 (04) ◽  
pp. 285-296 ◽  
Author(s):  
K. SENGUPTA ◽  
G. SINGH ◽  
P.L. JAIN
Keyword(s):  
Multiplicity Distribution ◽  
Charged Particles ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Minimum Bias ◽  
Target Region ◽  
Ion Collisions ◽  
200 Gev ◽  
Multiplicity Distributions ◽  
Limiting Fragmentation

We report the analysis of multiplicity distributions of charged particles produced in central and minimum-bias interactions of 32S ions at 200 GeV/n and 16O ions at 200 and 60 GeV/n with nuclei of emulsion. The minimum-bias events exhibit scaling in normalized multiplicity distribution, while the central events do not. The pseudorapidity distributions in minimum-bias events show limiting fragmentation in the target region. We have also analysed the forward-backward multiplicity correlations using the concept of “mutual information”

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