A muon detection system (MUCH) based on a novel concept using a segmented and instrumented absorber has been designed for high-energy heavy-ion collision experiments. The system consists of 6 hadron ...absorber blocks and 6 tracking detector triplets. Behind each absorber block a detector triplet is located which measures the tracks of charged particles traversing the absorber. The performance of such a system has been simulated for the CBM experiment at FAIR (Germany) that is scheduled to start taking data in heavy ion collisions in the beam energy range of 6–45AGeV from 2019. The muon detection system is mounted downstream to a Silicon Tracking System (STS) that is located in a large aperture dipole magnet which provides momentum information of the charged particle tracks. The reconstructed tracks from the STS are to be matched to the hits measured by the muon detector triplets behind the absorber segments. This method allows the identification of muon tracks over a broad range of momenta including tracks of soft muons which do not pass through all the absorber layers. Pairs of oppositely charged muons identified by MUCH could therefore be combined to measure the invariant masses in a wide range starting from low mass vector mesons (LMVM) up to charmonia. The properties of the absorber (material, thickness, position) and of the tracking chambers (granularity, geometry) have been varied in simulations of heavy-ion collision events generated with the UrQMD generator and propagated through the setup using the GEANT3, the particle transport code. The tracks are reconstructed by a Cellular Automaton algorithm followed by a Kalman Filter. The simulations demonstrate that low mass vector mesons and charmonia can be clearly identified in central Au+Au collisions at beam energies provided by the international Facility for Antiproton and Ion Research (FAIR).
Ultraperipheral heavy-ion collisions provide a unique opportunity to study two-photon-induced processes. Production of tau-lepton pairs in the process
at the LHC is of particular interest, since its ...cross section is sensitive to poorly known electromagnetic moments of the
lepton. Possible deviations of the anomalous magnetic moment
of the
lepton from the Standard Model predictions may indicate the presence of effects beyond the Standard Model, such as contributions of supersymmetric particles to the lepton production or the composite nature of the
lepton. The prospects for measurements of the exclusive cross section of
lepton production in ultraperipheral Pb–Pb collisions at the LHC are discussed, and esimations of possible
limits are presented.
Neutral Mesons and Dielectrons Kryshen, E.; Riabov, V.; Rufanov, I. ...
Physics of particles and nuclei,
07/2021, Letnik:
52, Številka:
4
Journal Article
Recenzirano
We review the performance of the MPD detector at NICA for measurements of neutral mesons, dielectron continuum and light vector mesons. Results of feasibility studies for the reconstruction of these ...observables and estimations of the required statistics are presented and discussed.
The future MPD experiment at the NICA collider is aimed to study hot and dense matter created in heavy-ion collisions at center-of-mass energies of 4 to 11 GeV. Measurements of photon spectra via ...reconstruction of electron–positron pairs from photon conversions provide a unique opportunity to probe the temperature of the produced medium and study π
0
- and
-meson yields down to low transverse momenta. In this work, feasibility of photon conversion measurements in the MPD experiment is discussed. A proposal to increase the photon conversion probability using a dedicated retractable converter is presented, and prospects for probing the material budget of the experiment using converted photons are evaluated.
Ultra-peripheral Pb-Pb collisions, in which the two nuclei pass close to each other, but at an impact parameter greater than the sum of their radii, provide information about the initial state of ...nuclei. In particular, heavy vector meson production, where the particle mass sets a hard scale, proceeds in such collisions by photon-gluon interactions, and gives access to nuclear PDFs. The ALICE collaboration has published measurements of J/ψ and ψ(2S) photoproduction in ultra-peripheral collisions in LHC Run 1 at forward (J/ψ) and mid-rapidity, and has obtained a substantially larger data set in 2015 from LHC Run 2, allowing much more detailed studies of the production mechanism to be performed. In particular, the increased energy and more detailed measurements in the forward region in Run 2 give access to significantly lower values of Bjorken-x than in previous studies. In this talk, the latest available results from Run 2 will be given.
Abstract
The short-lived hadronic resonances are used to study properties of the hot and dense medium produced in relativistic heavy-ion collisions. Due to their short lifetimes, the resonance yields ...and masses measured in the hadronic channels are sensitive to rescattering and regeneration effects in the hadronic phase. The measurement of resonances is foreseen in the physical program of the MPD experiment at NICA in heavy-ion collisions at
S
N
N
=
4
-
11
GeV
, in the range of energies where extensive measurements of resonances are not experimentally available. In this contribution, we explore the sensitivity of the ρ(770)
0
, K*(892), ϕ(1020), ∑(1385)
±
, Λ(1520) and Ξ(1530)
0
resonances measured in the hadronic decay channels to different stages of the heavy-ion collisions at NICA energies and report the feasibility studies for the reconstruction of resonances in the MPD setup
Thermal photons serve as valuable probes of the hot and dense medium produced in heavy-ion collisions. The effective thermal photon temperature measured at RHIC and LHC energies far exceeds the ...temperature predicted for the phase transition into the deconfined state of quarks and gluons, known as quark-gluon plasma. Direct photon measurements in heavy-ion collisions at the future NICA collider may help to estimate the effective temperature of the produced medium and trace the transition from the quark-gluon plasma to the hadron gas state at lower energies. Measurements of neutral meson spectra and extraction of the corresponding decay photon distributions is essential for direct photon studies. In this contribution, we present feasibility studies on the neutral meson and thermal photon measurements in Au–Au collisions using the photon conversion method in the MPD experiment at NICA.
The results of development of the technologies ensuring an increase of wear resistance, lowering of noise and vibration level in frictional units are discussed in the paper. The most efficient ...technologies of formation of fluorinated microsized films on the friction surface improving the wear resistance, contact fatigue and durability of connection of the lubricant layer with friction surfaces; molecular reinforcement of surface defects decelerating the development of fatigue damages; the effect of multilubrication improvng adhesion and load characteristics of the lubricant layer, its absorbing capacity, etc. are determined. The technology of formation of fluorinated films is implemented by the introduction of graphite fluoride additive to lubricant oil. In the case of molecular reinforcement the effect of increasing wear resistance and contact endurance is connected with the passivation of surface defects formed in final treatment. Defect passivation is realized by dipping of the processed details in the oil containing solid particles in the resonant mode. In the case of multilubrication the effect of creating an underlayer of lubricant on the basis of a highly adhesive material, for example, of polimetilsiloksan produced by the JSC TogliattiAzot is realized. The creation of a low frequency cavitational method and installations for washing parts of friction units at the Nadezhnost Research and Development Center of SSTU is a important collateral development. The first installations are implemented at the JSC Progress SpaceRocket Center and the JSC Aviaagregat of the Tekhnodinamika Holding.
—
This paper presents the results of estimating the changes in the yields and spectral properties of hadronic resonances in heavy ions collisions at NICA energies by the example of short-lived ...resonances
and
. The results of studying the feasibility of detecting hadronic resonances at the MPD detector in collisions of bismuth nuclei at an energy of 9.2 GeV are also presented.
Thermal photons are a valuable source of information about the properties of hot and dense matter produced in relativistic heavy-ion collisions. The effective temperature measured at RHIC and LHC ...energies greatly exceeds the temperature of the expected phase transition to the state with deconfined quarks and gluons known as quark–gluon plasma (QGP). Measurements of direct photons in heavy-ion collisions at the NICA accelerator will enable assessment of the effective temperature of the emerging medium at lower energies and trace the transition from partonic to hadronic degrees of freedom. The feasibility of studying thermal photons in the MPD experiment at NICA in Au–Au collisions using the photon conversion method is analyzed.
PDF
