The dissertation research covers the topics of works that are closely intertwined in the activities of every scientist who is professionally engaged in Experimental Nuclear, High Energy or Particle Physics. As a member of the International LHCb Collaboration (CERN), the author contributed to the physics analysis using data from the LHCb experiment to study the production of charmonium in ultraperipheral PbPb collisions at energy of √s_{NN} = 5.02 TeV, which initiated a new research area in heavy ion physics at the LHCb. The period of the dissertation work mostly fell on the stage of a significant upgrade of the entire experimental facilities and techniques at the LHCb. In this part of the research, the author has developed a design, manufactured and implemented an online luminosity and background monitoring system for the LHCb experiment commonly referred to as RMS-R3.
From the experiment set-up’s perspective, it is of key relevance to ensure reliable and comprehensive monitoring of the beams collisions and background generated by the Large Hadron Collider, which together form a new environment near the LHCb IP8 interaction point. The solution to this problem is of paramount importance and promise: in the advanced development and testing of detector systems and readout electronics, in the implementation of complex experimental techniques, in opening new horizons in research, and, finally, in making fundamental discoveries.
The subject of the dissertation addresses two of these complex tasks. First, it is to perform experimental fundamental studies of processes and mechanisms of hadron production in heavy nucleus collisions at ultrarelativistic energy. Secondly, it is to create conditions for safe, stable, and uninterrupted operation of the LHCb experimental facility, which should be guaranteed by the reliability of the data obtained from monitoring systems.
The coherent production of J/ψ and ψ(2S) mesons in ultraperipheral PbPb collisions at the nucleon-nucleon center-of-mass energy of 5.02 TeV is studied for the first time using the LHCb hadron spectrometer (CERN). A significant physical quantity is obtained — the coherent J/ψ production cross-section within the forward rapidity range of 2 < y < 4.5 was measured to be 4.45 ± 0.24 ± 0.61 mb, where the first uncertainty is statistical and the second systematic. A method for analysing photon-nucleus reactions in ultraperipheral heavy ion collisions has been developed in the LHCb experiment. This work enriches the unique field of research on hadron production in strong electromagnetic fields and at ultrarelativistic energy, which are currently achievable only at the Large Hadron Collider.
For the purpose of monitoring the conditions and safety of the LHCb experiment, a unique RMS-R3 system with its own dynamic range from about 1 Hz to 1 MHz for measuring the interaction rate of Large Hadron Collider beams that covers the nominal instantaneous luminosity for proton-proton collisions of 2 × 10^{33} cm^{−2}s^{−1} with a 10-fold capacity was developed and implemented. A new approach and new technical solutions to the construction of a reliable and super-sensitive system, designed for online beam and background monitoring, based on the technologies of metal sensors and high-precision charge converters have been invented. The following crucial physical and technical characteristics of the RMS-R3 system have been achieved: femtocoulomb sensitivity to charges in metal sensors, excellent linearity of the response over the entire dynamic range, high temporal stability of the response, and long-term operation of sensors under the impact of ultrahigh radiation levels (up to about 1 GGy).
The differential cross-section dσ^{coher.}/dy for coherent production of vector J/ψ mesons as a function of rapidity y at √s_{NN} = 5.02 TeV makes it possible to study, using valuable experimental data, the sensitive kinematic region at poorely explored values of the Bjorken variable x and transverse momentum. The result is essential for testing phenomenological models describing such phenomena as nuclear shadowing, gluon saturation, and determination of the initial state of the quark-gluon plasma.
The built radiation hard system for monitoring the conditions and safety of the LHCb experiment is a promising prototype of the up-to-date systems capable of operating at ultra-high luminosity levels (radiation load, multiplicity of processes) in experiments at future HL-LHC, FCC colliders, etc. The RMS-R3 monitoring system is a unique specialized experimental device designed, built and implemented by Institute for Nuclear Research, National Academy of Sciences of Ukraine, which has been successfully applied in the LHCb experiment for the Run 3 series of studies (2022-2025) at the Large Hadron Collider.
