At PAC meetings

Progress at the NICA accelerator complex,
visiting experiments, future plans

On 23 June, the 62nd meeting of the Programme Advisory Committee for Particle Physics was held at the JINR International Conference Centre.

The meeting started with a minute of silence in memory of the famous scientist Hans Gutbrod (GSI) that had for many years been a member of the PAC for Particle Physics and had warmly supported cooperation with JINR and the NICA project.

It was followed by a report by PAC Chairman Itzhak Tserruya on the implementation of the recommendations of the previous meeting. Information on the resolution of the 137th session of the Scientific Council in February and the decisions of the Committee of Plenipotentiaries of the Governments of JINR Member States, held in March, was presented by JINR Vice Director Vladimir Kekelidze.

Furtherly, reports on the implementation of current projects at the NICA accelerator complex were delivered at the meeting. Deputy Head of the Acceleration Department for Research of VBLHEP Anatoly Sidorin spoke about the Nuclotron-NICA project. The PAC members praised the progress in optimizing particle dynamics in the booster that allowed implementing an electron-cooled beam accumulator. Completion of the assembly of the components of the system of the pulsed extraction of beam from Nuclotron, preparation for the operation of its cryomagnetic system were highlighted with satisfaction. Construction on the mounting of the beam transportation line from Nuclotron to the collider in building No.1 has also been completed and the collider assembly successfully advances. Vacuum tests of the Western arch of the collider and the assembly of its cryomagnetic system are at the final stage. Commissioning of the NICA beam, as previously reported, is scheduled before the end of the year.

The progress of the BM@N project was also highly appreciated. A report on it was presented by Head of the Department of Baryon Matter at the Nuclotron of VBLHEP Mikhail Kapishin. The BM@N team focused on calibrating the time-of-flight system and developing techniques to estimate centrality in 3.8 AHeV Xe+CsI collisions. The data were reprocessed on MICC and VBLHEP computers to introduce improved reconstruction techniques and new calibration constants. An article with physical results on the production of protons, deuterons and tritons in argon interactions with the nucleus at 3.2 AHeV has been submitted for publication in JHEP (Journal of High Energy Physics). The next physical launch of the BM@N experiment is scheduled with a beam of Xe ions with an energy of 2-3 AHeV.

A report on the implementation of the MPD project was presented by a chief researcher at VBLHEP Viktor Ryabov. The MPD pilot plant is in the final stages of construction. Commissioning of the detector is scheduled to begin at the end of 2025 with all Phase I detector subsystems of the MPD project. Extensive work is underway to commission a solenoidal superconducting magnet. Measurements of the magnetic field will start in summer and will take several months for various field configurations using a cartographer developed at BINP. A comprehensive study of the capabilities of the MPD experimental facility and its properties was carried out to measure various physical signals both in the collider collision mode and in collisions with a fixed target. They are currently published in two collaboration papers.

Achievements in the implementation of the SPD project were highlighted that was reported by DLNP Deputy Director Alexey Guskov. Work is underway to optimize the bearing structure of the detector and the external platform for the positioning of the equipment, as well as the design of lines of various communications. Documentation is currently prepared for the development of a superconducting solenoid. Thermal properties of detector components are analyzed. Production sites for the manufacture of gas detectors are currently constructed. A zero-angle calorimeter prototype is already installed in the collider ring near the SPD interaction point and a second prototype is expected to be installed in the near future. MICC has a specialized data storage for SPD with a capacity of 7.2 PB.

The next series of reports were dedicated to projects ending in 2025 and proposals for their extension.

Head of the Department of Multiple Hadron Processes of DLNP Yury Davydov spoke about the preparation of the project "Development of a physical programme and detectors for experiments at CEPC". The decision to start construction of a ring electron-positron collider (CEPC) in China is expected in 2026. However, preparation of the research programme and development of the technical project have been ongoing since 2012, after the discovery of the Higgs boson by the ATLAS and CMS collaborations. The main goals of CEPC will be precision research in the physics of the Higgs boson, Z boson, top quark physics and the search for new physical phenomena outside the Standard Model. The goal of this project is to prepare proposals for a research programme in the field of physics, to participate in software development and theoretical calculations, as well as to carry out a series of investigations and development of detectors for experiments at CEPC. Over the next two years, conditions will be established for the future long-term participation of JINR in experiments at CEPC, subject to the approval of the construction of this accelerator by the Chinese government. Given the importance of preparing for the full participation of JINR in the CEPC experiments, it is recommended to extend this project to 2026-2027 with priority A.

The report on the progress of the JINR group in the ALICE experiment at the LHC was presented by Head of Sector of VBLHEP Boris Batyunya. The results of the analysis of data on femtoscopic correlations of kaons, the production of vector mesons and hyperons were published and presented at various conferences and further research is scheduled. The JINR team will participate in the support and development of a new fast trigger for the interaction of nuclei, in carrying out work on this system and in supporting the GRID-ALICE system in JINR. These plans were approved by the PAC members, the JINR participation in the ALICE experiment was decided to be extended until 2030 with priority A.

The results obtained by the JINR group in the ATLAS experiment at LHC were reported by Head of Sector of DLNP Ivan Eletskikh. The significant contribution of JINR physicists to physical analysis, software development and detector modernization was highlighted. The JINR staff is extensively engaged in the development and support of ATLAS software, a significant contribution has been made to the modernization of various detector subsystems. Based on the results of the discussions, JINR's participation in the ATLAS experiment was also extended until 2030 with priority A.

Head of the Department of Physics at CMS of VBLHEP Vladimir Karzhavin presented a report on the participation of the JINR group in the CMS experiment in two projects ("CMS" and "Modernization of the CMS detector"). The PAC members emphasized the significant contribution of JINR to the support and operation of the hadron calorimeter and the CMS end muon system during the period of the RUN3 data accumulation to ensure their reliable operation. JINR Tier-1 and Tier-2 Grid Centres were widely and constantly used to process and store experimental data from the CMS detector. In the framework of the CMS modernization, the JINR specialists are actively involved in the development of the highly granular HGCAL calorimeter and the modernization of the end muon system. The PAC highlights with satisfaction the large number of publications with key contributions from JINR physicists. A significant number of conference reports were presented by young scientists. At the PAC meeting, the uniting of two projects into one was supported - "Physical investigations in the CMS experiment and the second phase of modernization of the facility for operation in high luminosity conditions". It was recommended to extend JINR's participation in the CMS experiment until 2030 with priority A.

The scientific report "Theoretical calculations for future electron-positron colliders: state and prospects", presented by Head of Sector of BLTP Andrey Arbuzov, was dedicated to the prospects for high-precision verification of the Standard Model and the search for new physical phenomena at future high-energy electron-positron colliders. Some advances in high-precision calculations of observed quantities for processes studied in electron-positron colliders were presented, as well as ways for further improvement of theoretical accuracy to the level required for future experiments. The participants in the meeting of the Programme Advisory Committee thanked the speaker for an interesting speech.

At the traditional poster session, 22 reports of young scientists from DLNP, MLIT and VBLHEP were presented. The Committee selected the report "Measurements of di-leptons in the MPD experiment at NICA" by Sudhir Pandurang Rohde for presentation at the next session of the Scientific Council to be held in September.

Galina MYALKOVSKAYA,
photo by Igor LAPENKO