PROBES has moved along three complementary directions: hadron physics at JLAB (US), muon and neutrino physics at Fermilab (US), PSI and CERN (Switzerland) and J-PARC (Japan), and Gravitational Wave physics at LIGO (US), EGO (Italy) and Kagra (Japan).
During the reported period, the JLAB accelerator complex has been regularly operated and the planned data-taking in Hall-A and Hall-B have been successfully completed. Among the major achievements were the completion of the first experiment of CLAS12 (Hall-B) with a (longitudinally) polarized target and several nucleon form-factor experiments done with the SBS spectrometer (Hall-A). PROBES Researchers largely contributed to the tuning of the detector reconstruction parameters and algorithms, to the data processing, data quality assurance and high-level analysis. This led to a continuous flow of publications, with highlights from nucleon structure (tritium targets and GPD and TMD parton distributions), nuclear potentials (CREX experiment) and dark matter searches (HPS experiment and BDX-mini demonstrator).
PROBES Researchers have been provided leading contribution to the development, construction, commissioning and operation of the experiments dedicated to the search for Charged Lepton Flavour Violation. These include COMET at J-PARC, MEG-II and Mu3e at PSI, and the muon-electron-conversion (Mu2e) experiment at Fermilab. MEG-II has already published their first articles on physics data analysis, COMET, Mu3e and Mu2e are rapidly progressing towards the completion of infrastructure and detectors commissioning and physics data taking. In the field of neutrino physics, ICARUS (Fermilab) has been successfully taking data for three years and SBND (Fermilab) has completed commissioning and is beginning physics data taking in conjunction with ICARUS within the SBN program.
Following the success of the initial observational campaigns (O1, O2, and O3), the global network of Gravitational Wave detectors, comprising LIGO, Virgo, and KAGRA, has continued its scientific program through a series of alternating observation periods and detector upgrades. The recent data-taking periods include O4 (started by LIGO in May 2023), and O5, expected in 2027. In the case of Virgo, the detector has undergone significant improvements to become Advanced Virgo+ and joined LIGO in O4 as of May 2024.
In parallel with the ongoing operation of Virgo, PROBES Researchers are deeply involved in the design of the Einstein Telescope (ET) which represents the next generation of Gravitational Wave observatories, designed to enhance the sensitivity of current detectors by an order of magnitude and extend the frequency range towards lower frequencies. Progress has been also made in the localization strategy of Gravitational Waves events to perform multi-messenger studies including electromagnetic and other cosmic-messenger counterparts.
