LHCb, Flavour physics, QCD processes, research and development at LHCb or DRD4, and LS3 Enhancement of the RICH subdetector electronics

in English  in Romanian

Financing source (agency):    Institute for Atomic Physics (IFA)

Project code:    PN IV, Module CERN-RO, Subprogram 5.9.2, Project 9/25.11.2024; LHCb: contract no. 08/25.11.2024

Project duration:    25.11.2024 to 31.12.2026

Project director:    Dr. Florin MACIUC

Institutions:

Coordinator:"Horia Hulubei" National Institute for Physics and Nuclear Engineering (IFIN-HH),
30 Reactorului, P.O.B. MG-6, RO-077125, Bucharest-Măgurele, Romania, EU
Partner:Ştefan cel Mare University of Suceava (USV), Str. Universitatii 13, RO-720229 Suceava, Romania, EU

E-mail: florin {dot} maciuc [at] cern < dot > ch

Research Team: see TEAM menu entry for a detailed overview of present and former members of the research team.

Most of the present project and the past projects activities are given in detail in the subchapter pages: Team, Research Topics, Service Tasks, Group Seminars, Conference Participation, Publications, Outreach, LHCb Upgrade, Research Facilities accessible from this main page.

Project Summary (as given in grant application)

This project proposes a major contribution to the next Upgrade of LHCb RICH detectors, proposes one new LHCb study in the field of QCD interactions, and proposes a prospective rare decay study for the beauty-baryons. Besides the enhancement of the RICH electronics in third Long Shutdown of LHC (LS3), we propose a major research and development (R&D) program dedicated to improving generic Particle Identification Systems, and in particular LHCb-RICH. We expect to play a vital role in the RICH Enhancement during LS3 and an equally important role in the RICH TDR (Technical Design Report) Upgrade activities, the latter being scheduled to finalize during 2026. Our group will be vital to the success of LS3 Enhancement/Upgrade as we have developed the necessary knowhow and infrastructure to help the LHCb-RICH group and CERN’s electronics group by characterizing the vital FastRICH chip. Also, we have designed the first digital carrier board prototype which is dedicated to the LS3 Enhancement program and beyond. This first design will be improved such as to take full advantage from the new radiation hard CERN ASICs and modules: FastRICH (to be delivered by CERN around June 2025), bPOL DC-DC converter power module, and the latest lpGBT (Low Power GigaBit Transceiver) ASIC for communication modules. The digital board and the FastRICH chip will be integrated in a Photon Detector Module prototype, which will have to be tested at the CHARM facility within CERN. We are expected to contribute to the design of FastRICH and lpGBT plugin boards attached to our digital board. This project foresees that we shall construct in Bucharest most of the digital boards and support the costs for bPOL devices and their addons which are embedded in the digital board.
The project includes a study of LHCb data from the present LHC Run (RUN3), which will investigate a few hard-QCD processes and the associated underlying event structure. In first phase we aim to parametrize the underlying event in the collisions with Drell-Yan or quarkonia production. Thus, we measure the underlying event characteristics like particle multiplicity distribution, transverse momentum spectra, rapidity distribution, light flavour content, baryon transport, etc. In a second phase, shall select the same hard-QCD processes with production of Z/γ* or quarkonia in collisions, and compute differential cross-sections of long lived V0 or heavy flavour hadrons, i.e., charmed hadrons, for such collisions. The second study we are proposing is a study of the key rare decays of beauty-baryons Λb (Ξb) to the long lived Λ (Ξ or Λ) and a lepton pair, or similar FCNC decay channel. These are tree-level suppressed Flavour Changing Neutral Current (FCNC) transitions, and we propose to measure decay parameters like branching ratios, which for some rare decays of Ξb would be a novelty. Next, if time and workforce availability allow it, we shall do a first comparative study these baryon decays, otherwise this will be postponed to after 2026. Some of these decays were not truly measured before, and no branching ratio is known, but the hope is that the increased luminosity in this LHC run would allow us to obtain a significant candidate sample, even before the 5th and 6th runs of LHC.
In addition to research and development or data analyses, we are to provide necessary services to the LHCb collaboration. We contribute to the LHCb Simulation group software, with maintenance and development. We have a leading role in converting LHCb measurement to HEPData format, uploading to this database, and providing guidance to LHCb groups in their RIVET plugin development. We assume we support more than 30 shifts and piquet per year, and similar services for the RICH test beams at an SPS/CERN facility. The project includes Outreach events, and we committed to our students to include them in important R&D and data analysis studies which would constitute their thesis work at PhD level and MSc level. The proposed ratio of students to researchers is 8 to 11, with one engineer and one staff in addition. Teams from two institutes will be involved in this project, the “Horia Hulubei National Institute of Physics and Nuclear Engineering” (IFIN-HH) and University “Stefan cel Mare” from Suceava (USV).

Objectives of the CERN Experiment (as given in grant application)

The LHCb experiment is dedicated to the study of charm and beauty hadrons. More generally, though, the collaboration is interested in precise measurements of Standard Model (SM) Physics, and the possibility to indirectly infer about the existence of physics beyond the Standard Model of elementary particles. This indirect discovery of New Physics (NP) is pursued by the LHCb teams in, e.g., matter anti-matter asymmetry studies, lepton flavour universality studies, QCD and Electro-Weak (EW) studies. The purpose of the experiment goes beyond the context of SM measurements and indirect evidence of NP, and there are many other studies done at LHCb. An extended list of analyses would necessarily include ion-ion collision physics, direct search for exotic particles, spectroscopy studies (like penta- and tetra-quark states), or hadron physics measurements where the colour-charge nature of the QCD theory is not apparent – e.g., diffractive, Minimum Bias physics, other long-distance effects. A list of LHCb objectives would include, potentially, most High Energy Physics (HEP) measurements possible at LHC collision energies. One point of interest is the CKM (Cabibbo – Kobayashi Maskawa) angles and CP-violating phase which parametrize the transition amplitude of some “golden” flavour-physics decay channels of beauty and charm hadrons. Measuring the mixing parameters of the B0 B0-bar and D0 D0-bar systems in oscillations of CP eigenstates – i.e. CP-violation - could point or lead to a discovery of NP contributions to such matter anti-matter asymmetry. Rare decays of heavy-flavour hadrons are another point where NP contribution could play a significant role. In this context the LHCb collaboration investigates for example Flavour Changing Neutral Current (FCNC) transitions, like $b \to s \mu^+ \mu^-$. The SM transition amplitudes for these transitions is small and possible large contributions from NP would be easy to spot.
To understand and measure the underlying elementary-particle physics at energy scale accessible to the LHC collaborations, it is required to understand that most QCD physics is not available directly, but any measurement depends on parameters from long-distance contribution to transition amplitudes. More, in most hard-QCD processes, the SM Lagrangian is not useful directly and effective-field theory parameters have to added to the transition amplitudes and the underlying physics theory. For the soft-QCD processes, it is impossible to apply directly the pQCD approximations, and more heuristic approaches are required, some based on Regge theories, some are inspired from the parton model, other are mixed approaches, and hadronization is described purely heuristically. We did not include QCD lattice approaches in some hard-QCD problems, yet, but in some of the next concepts this will be implicit. LHCb can measure or constrain some of these parameters of interest in addition to the pure QCD colour charge observables. The list of such parameters includes Wilson Coefficients, hadronization flavour and baryon (diquark) parameters, parton PDFs, fragmentation functions, etc.
The LHCb detector is a single-arm spectrometer which is fully instrumented in the forward direction of high rapidity, with y in [2,5]. It also allows to precisely detect and identify long-lived particles (final state particles) with beam-transverse momenta with values ranging from few tens of MeV to several tens of GeV. Beyond the fundamental physics research studies, the research and development results and activities are included among the most interesting LHCb objectives – these R&D tasks are done usually for LHCb Upgrades. It is the LHCb community aim to transfer some of these achievements in detector physics to new CERN experiments or to the whole society. This is being investigated in present and future workshops of DRD4 collaboration – “Research and Development for Photon Detectors and Particle identification Techniques (DRD4). The latter has Applied Physics goals in the field of RICH detectors, Photon-Counter and photon sensors, material science, scintillating-fibre trackers, and so on. There almost 100 % synergy between the R&D program of the LHCb-RICH detectors and the DRD4 groups of RICH and photon sensors. Here a strong relationship with the major industrial players is to be expected.

Project Objectives (as given in application to IFA)

Proposed objectives for our group analyses are mostly concentrated on QCD studies and impact of such measurements on Generator models, their parameters, and on the underlying theories. Compared to Electro-Weak theory, the QCD running coupling constant leads asymptotically to free colour charges at short distances, and to hadronization at large-distances. There is a large set of model parameters which parametrize the QCD processes physics at large distances, and there are even models not directly connected to the underlying QCD theory. Our plan is to measure certain observables, and to fix or constrain some of the model parameters. One general set of observables which we plan to measure in first step is the underlying event in the Z production proton-proton collisions – Z decaying to two muons. In the second phase we plan to include studies of strangeness and charm production in such Z-production collisions, as well as in the events containing already a J/Psi or Upsilon – in place of a Z0 resonance decaying to muon pair, there is a quarkonia meson. In context of these measurements, we shall compute differential cross-section of strange/charm particle production associated to these hard-QCD events, and the cross-section measurements will depend on the various scales of collision energy in the parton-parton system which produces the resonance (Drell-Yan or quarkonia). The underlying event will be characterized by measuring the spectra of transverse momenta, rapidity values, event multiplicity, strange particles to lighter hadron ratios, baryon transport, etc. The same data can be used to do a spectroscopy study of heavy flavour hadrons with charmonim/bottonium and strange hadrons in final states after decays. We look for new PhD students which would take new LHCb analyses in rare decays of beauty or cham baryons for certain FCNC decay channels.
After some considerable efforts from our more senior team, we were able to hire in 2022-2023 five new students. Three were at level of bachelor students at IFIN-HH and now are in the first year of MSc studies. One student was at level of MSc studies when hired, and this September has applied for a Doctorate at University of Bucharest and has placed first at admission in September 2024. Now she has started an LHCb and HEP thesis. One bachelor student will start a bachelor thesis in our group after also being an official summer student for a few months. All these students have exclusively LHCb and HEP topics. We hope to further their carriers in the future with an LHCb-listed doctoral dissertation. This will allow us to partially justify the future investment in LHCb LS3-LS4 Enhancements and Upgrade, i.e., add 10 new PhD thesis at LHCb during the next 10 years from students in our LHCb-Romanian group.
The first objectives of our group in LS3 Enhancement and LHCb U2 is to contribute significantly at the R&D studies of electronics and sensors. We already have invested a significant amount of money and time to develop the infrastructure, and to design and build several test benches for Integrated Circuits and for sensors. We aim to test Photon Detector Modules based on Integrated Circuits like FastRICH chip, lpGBT modules, and DC-DC bPOL, all three developed by CERN electronics group. We continue testing Photon counters like SiPM and MCP – micro channel plate sensor. We intend to develop electronics and Photon detection module capable to detect Cherenkov photons with precise arrival timing within 100 of pico-seconds precision, or better, for MaPMT (Multi-anode PhotoMultiplier Tubes are used in RUN3 and RUN4) and SiPM (RUN5 and RUN6? to be confirmed). For now, our main hardware task in this program is the development of the digital carrier board which acts as mother board for most front-end electronics of RICH. We also will contribute to the FastRICH and lpGBT plugin board together with our RICH partners.
One main tasks and objective in 2025-2026 will be the FastRICH and PDM irradiation campaign and laboratory testing. We have taken the responsibility to tests FastRICH in laboratory and to characterize its radiation-harness, too. For this we shall implement a testing program based on ions irradiation – Liner Energy Transfer values of 1 to 70 MeV cm2/mg – and X-ray tests with Total Ionization Dose of up to few Mrads or few 10 kGy. On the other hand, the cumulative damage in Silicon layers of SiPM is usually parametrized in fluence with values reaching several times of 10^{13} 1-MeV neutron equivalent/cm^2. This damage can induce large dark-currents and large rates of dark counts. To diminish this noise, the prosed solution is a mixture of annealing in off state, and next operating the chip at very low temperature (close to liquid nitrogen temperature). Hence, we shall continue to irradiate SiPMs with protons or neutrons and test the samples in special condition of temperature. We already located a good facility to test SiPMs operating at -160 degrees Celsius. In a nutshell our objectives are focused on the goal of constructing a fully 4D single arm spectrometer, which would resolve each individual collision final state in a 4D (3D geometrical plus Time) reconstruction. However, to do this the tracking and Particle Identification detectors will have to be capable of very precise timing. Our objectives within DRD4 collaboration are to advertise the results obtained for our irradiation and testing campaign, and to propose solutions to general applied physics problems by using the results and the knowhow developed at LHCb in the outlined activities and programs.
We have already discussed the generator studies to be conducted in IFIN-HH and USV. By using the HEPData measurements from LHCb and other similar experiments we test the limitation of generator tunes and search for better set of tuning parameters. The objective of popularizing our results and the CERN science is to be done in conference or general-audience talks, and outreach events, e.g. HEP Masterclasses from IPPOG. We expect a RICH publication output for next two years from all the outlined programs and tasks.

List of activities and subactivities for 2024-2026 (as stated in project proposal)

Stage I: LHCb and DRD4 2024 end of year activities

Activity I.1. Physics analyses and Generators
Subactivity I.1.1. LHCb internal review of V0 paper, initialization of new analyses, some trigger coding
Subactivity I.1.2. Software Maintenance and HEPData, preparation of outreach events for next year, student tasks for data generation and processing, generator studies

Activity I.2. Research and Development for RICH
Subactivity I.2.1. FastRICH test bench preparation, FastRICH-substitute test board, FPGA TDC/ToT Time-Digital-Converter and Time over Threshold
Subactivity I.2.2. SiPM testing in laboratory, optimization of test bench.

Stage II: LHCb physics data and Enhancement, DRD4 Photon-Counters and RICH electronics

Activity II.1. Data analysis and Simulation Models
Subactivity II.1.1. Data taking 2025 and analysis of 2024 LHCb data, including $Z^0$ studies and underlying event, trigger optimization
Subactivity II.1.2. Generator studies - PYTHIA, HERWIG and Sherpa - of hard-QCD events, tuning checks for LHCb, software and maintenance - including HEPData -, outreach

Activity II.2. LS3 Enhancement, sensors and electronics
Subactivity II.2.1. Reconstruction of RICH electronics for LS3,Tests of FastRICH chip and Photon detector module, includes all payments to LHCb and CERN, including LHCb annual tax
Subactivity II.2.2. Sensors testing in radiation, low temperature testing, annealing studies of SiPMs

Stage III: Analysis of data, Simulations, DRD4 tasks or presentations, and the Enhancement of RICH PID reconstruction

Activity III.1. 2025 data analysis, hard-QCD process study and Underlying event
Subactivity III.1.1. Data taking 2026, Triger checks, analysis of 2025 data, hard-QCD and underlying event
Subactivity III.1.2. HEP analyses, generator studies, checks of Model and theoretical estimates with HEPData values, Software and maintenance, Outreach

Activity III.2. LS3 Enhancement, sensors and electronics - second phase
Subactivity III.2.1. Test of FastRICH chip and PDMs in mixed radiation field, tests of PDM prototypes, beginning of mass testing of FastRICH chips, assembly of PDMs
Subactivity III.2.2. Further annealing studies of SiPMs and timing studies of SiPM signal, analysis of MCP data, preparation of LHCb TDRs for LS4

Partial list of results (Nov. 25, 2024 - end of 2026)

Submitted, under review, or published papers in 2025

  1. G.C. Salavarin and V.M. Plăcintă, „Performance Assessment of bPOL12V Power Modules for the Next LHCb-RICH Front-end Electronics”, JINST 21 C04011, 2026, TWEPP 2025, Jan. 30, 2025, Rethymno, Crete Greece
  2. V.M. Plăcintă on behalf of LHCb RICH group, „The LS3 Enhancement of the RICH detectors”, RICH 2025, NIM A vol. 1086, 171384,, June 2026
  3. Roxana Mocanu et al., „QCD interactions and processes from sub-GeV scale to about 1 TeV scale in proton-proton collisions at \sqrt{s}=13 TeV", to be submitted for publication in peer-reviewed journal
  4. M. Bartolini, L.N. Cojocariu, V.M. Placinta et al., "LHCb RICH Fast-timing photon detection at the SPS charged particle beam", JINST, 20, P03034, 2025
  5. LHCb collaboration, "Measurement of prompt K0S and Lambda production cross-sections and ratios in proton-proton collisions at $\sqrt{s}=13$ TeV", (paper in internal review with, LHCb, analysis note authors: Alexandru Catalin ENE, Florin MACIUC, Alexandru Tudor GRECU, and it passed the LHCb review) – publication date set for middle of 2026; see public details here

More than 92 LHCb publication, which are published or aproved for publication papers: LHCb publications since 25th of November 2024.

As coordinator for LHCb at HEPData, one member of our group is involved in a growing number of data set publications (counting 14 in April 2026).

Articles to be submitted soon to journals

  1. Vlad Placinta et al., "Single Event Event cross-sections and Radiation-Hardness characterization of FastRICH chip using ion-beams and X-rays", to be submitted to NIM A or JINST
  2. Vlad Placinta et al. (on behalf of LHCb-RICH collaboration), "Novel Concepts for RICH Fast-Timing Electronics in View of the LHCb LS3 Enhancement program", conference proceeding, at Technology & Instrumentation in Particle Physics TIPP 2026, 2 - 6 February 2026, Mumbai, India, talk and proceeding in Proceeding of science: PoS - SISSA
  3. Other two papers for LHCb-RICH group, papers to which our LHCb-Romania members have contributions (one of them already sent to journal in March 2026).

Conferences with talk/poster contributions from LHCb-Romania

  1. V.M. Placinta (on behalf of LHCb-RICH), The LS3 Enhancement of the RICH detectors, XII International Workshop on Ring Imaging Cherenkov Detectors - RICH2025, 15-19 September 2025, Mainz, Germany (poster)
  2. G.C. Salavarin and V.M. Placinta, "Performance Assessment of bPOL12V Power Modules for the Next LHCb-RICH Front-end Electronics", Topical Workshop on Electronics for Particle Physics - TWEPP 2025, 6 - 10 October 2025, Creta, Greece (poster)
  3. V.M. Placinta and L.N. Cojocariu, "RAD-WATCH: A dedicated and versatile system for testing the radiation hardness of various integrated circuits", The HEPTech Best Practice Workshop, 5th June 2025, IFIN-HH, Romania
  4. Roxana Mocanu et al., "QCD processes at low energy scales and at the scale of Z0 boson resonance energy in proton-proton collisions at 13 TeV", la University of Bucharest, Annual Communication Session of the Faculty of Physics, 23rd May 2025
  5. Roxana Mocanu et al., "QCD interactions and processes from sub-GeV scale to TeV scale in proton-proton collisions at $\sqrt{s} = 13$ TeV ", "Dialoguri Doctorale în Fizică" at Bucharest University Faculty of Physics, 11th October 2025
  6. In addition: there were 2 talks at the collaboration workshops, "LHCb Week meetings", and more than 25 talks in LHCb workgroups at CERN, e.g., RICH-LHCb Workgroups, LHCb Simulation Work Groups, and QEE (QCD, EW and Exotica) LHCb physics analysis Work Group.

Patents

Two application for national patents were submitted to OSIM in 2023, and in 2025 these were approved by the Romanian National Agency:

  1. Patent application no. RO 139131 A2, "PLATFORMĂ MULTISENZOR DE MONITORIZARE ÎN TIMP REAL PE LUNGA DURATĂ A MEDIULUI ŞI A FONDULUI NATURAL DE RADIAŢIE DIN INTERIORUL CLĂDIRILOR", see OSIM, Buletin oficial de proprietate industrială, nr. 9/2025, p. 43 (in Romanian only)
  2. Patent application no. RO 139129 A2. "SISTEM CU FOTODIODE PENTRU MONITORIZARE ÎN TIMP REAL A PARAMETRILOR SPECIFICI FASCICULELOR DE PARTICULE ACCELERATE", see OSIM, Buletin oficial de proprietate industrială, nr. 9/2025, p. 41 (in Romanian only)


Succesful aplications for funding from two Horizon 2020 programs - H2020

Other services done by the group, and other results:

We had done 29 "shift" sau "piquets" in 2025, and approximately 40 in 2026.
Outreach (popularization of CERN and LHCb and academic community, in highshool, and to general public) : e.g., 3 IPPOG Masterclass LHCb/CERN/IFIN-HH/USV events organized in Bucharest and Suceava in 2025-2026. Includes also: visit at CERN of highschool professors from the county of Suceava, 22-28 February 2025; Researchers' Night, 26 September 2025 in Bucharest and Suceava; Night of Museums - 17th May 2025; Preparation of Olympiad teams for the International Olympiad in Astronomy and Astrophysics (including LHCb and CERN topics), Suceava 2025; Support for "Summer School of Science and Technology", 22.09.2025-05.10.2025, Bucharest and other outreach events.
4 phase reports for NUCLEUS project at IFIN-HH Department of Elementary Particle Physics between 2025 and 2026. Work done by our group for NUCLEUS has 100% synergy with the LHCb-Romania projects.