The possibility of measuring antiproton production in heavy-ion collisions at the NICA (Nuclotron based Ion Collider fAcility) accelerator complex in a kinematical region that is forbidden for ...nucleon–nucleon interaction is considered. It is shown that, at pseudorapidities accessible to measurements with the aid of the NICA detectors and which lie in the range of
–1.5, the transverse momentum of an antiproton produced on a cluster formed by two nucleons does not exceed 6 GeV and is nearly twice as great as the transverse momentum of an antiproton produced in nucleon–nucleon interaction.
We review the context, the motivations and the expected performances of a comprehensive and ambitious fixed-target programme using the multi-TeV proton and ion LHC beams. We also provide a detailed ...account of the different possible technical implementations ranging from an internal wire target to a full dedicated beam line extracted with a bent crystal. The possibilities offered by the use of the ALICE and LHCb detectors in the fixed-target mode are also reviewed.
Determining the centrality of a collision, or the impact parameter, in heavy-nucleus collisions is important for the analysis of all experimental data and their comparison with theory. One of the ...methods for this is to measure the number of spectators using a hadron calorimeter arranged at a small angle to the nuclear beam. It is shown that the accuracy in determining the impact parameter at the attainable energy resolution of the hadron calorimeter is inadequate for using the calorimeter in the MPD/NICA and CBM/FAIR projects. The error is as large as 35% at the beam energy of 2.5 GeV even for peripheral collisions. Secondary processes during the motion of spectators through a nucleus make an additional contribution to the error for central and mid-central collisions.
Measurement of the number of spectators in nucleus-nucleus collisions could be used to determine the number of nucleons participating in the interaction, i.e. get information about collision ...centrality. However, at energies of the NICA collider energy resolution of the forward hadron calorimeter is insufficient for separation of the amplitudes corresponding to different number of spectators. Uncertainty in the number of spectators leads to a large error in determining the centrality. For central events inaccuracy in determining the collision parameter is about 40%, for peripheral ones, no better than 30% at a beam energy of 2.5 A×GeV. The multiplicity scintillator detector will allow to obtain more accurate data. A certain method is proposed for determining the centrality, taking into account the real MPD installation geometry.
Prototype of the fast timing Cherenkov detector, applicable in high-energy collider experiments, has been developed basing on the modified Planacon XP85012 MCP-PMT and fused silica radiators. We ...present the reasons and description of the MCP-PMT modification, timing and amplitude characteristics of the prototype including the summary of the detector's response on particle hits at oblique angles and MCP-PMT performance at high illumination rates.
A detector for adjusting the convergence of beams at the point of interaction of the MPD (multi-purpose detector) installation at the NICA collider (nuclotron-based ion collider facility) is ...discussed. Simulation of the detector operation for Au
Au collisions at
GeV is calculated. It is shown that background events from scattering on residual gas give a negligible contribution to the detector’s samples. It is discussed how to use a detector to adjust beam alignment. The calibration procedure for obtaining absolute luminosity in the MPD interaction zone with the help of this detector is considered.
The paper presents the characteristics of impact diamonds from the Popigai meteorite crater, formed by martensite transformation of graphite-bearing gneisses due to meteorite impacts. These diamonds ...have a nanopolycrystalline structure and consist of two phases, i.e., cubic (diamond) and hexagonal (lonsdaleite). They are distinguished by phenomenal abrasion resistance, on average twice as high as the abrasion resistance of single-crystalline diamonds. The work considers the possibility of producing similar diamonds by explosion. It is noted that diamonds, which are most similar in structure, are produced through exploding a composition of graphite and hexogen; lonsdaleite is present in the material obtained in this way. However, in any case, diamonds produced by explosion are very small in size, incomparable with natural ones.
.
The meassurements of charmonium states production via their decay on lepton pairs by the MPD experiment on the NICA collider at the energies
= 4-11 GeV per nucleon could provide important data for ...solving the problem of anomalous
J
/
suppression first observed in central Pb-Pb collisions by the NA50 Collaboration at 158 GeV/nucleon. The anomalous
J
/
suppression could be due to the formation of the QGP in the central heavy-ion collisions. However, this effect could be also interpreted as the result of the comover interactions in nuclear matter. The recent experiments at the SPS, at the RHIC, and the LHC reviewed in this article indicate a more complicated picture of the
J
/
production including the recombination, medium effects, parton shadowing, and the coherent energy loss mechanism. A more simple production mechanism could be expected at low colliding energies. However, no data were obtained at energies below
GeV for heavy-ion collisions. After the short review of the whole set of the data of charmonium states observation the estimation of the production rate for the MPD/NICA is made.
The brief review of the experimental data on quarkonium productions measured at the CERN SPS, at the Brookhaven Collider RHIC, and at the LHC is presented. The dissociation of quarkonium resonances ...produced in heavy ion collisions was suggested as a possible signal of the Quark-Gluon Plasma formation. At the CERN SPS, the anomalous suppression of the J / ψ production was observed in central Pb-Pb collisions by the NA50 collaboration. However, the effects of J / ψ suppression on cold nuclear matter, feed-down production from higher charmonium states, and regeneration processes should be taken into account. If proton and ion beams at the LHC will be used with fixed targets, the energy interval between the SPS energy and the nominal RHIC energy (200 GeV) could be investigated. The high statistics data on quarkonium productions at these energies will give the possibility of clarifying the mechanism of charmonium productions to investigate the importance of the recombination process, since the probability of recombination decreases with decreasing the energy of collisions.
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