The High Energy Cosmic Radiation Detection (HERD) facility is the flagship scientific experiment proposed for the China Space Station, with operations anticipated to begin no earlier than 2028 for a decade-long mission. HERD is designed to provide unprecedented measurements of cosmic nuclei, electrons, and gamma rays. IFAE joined the HERD collaboration in 2020, proposing the development of an “ultra-low” energy gamma-ray (ULEG) trigger to extend the mission’s sensitivity down to 100 MeV. Throughout 2025, this work reached a significant academic milestone with the completion of L. Fariña’s PhD thesis, which provided a thorough optimization of the ULEG trigger through full-detector simulations and a comprehensive study of HERD’s potential for detecting gamma-ray bursts.
Due to the absence of a high-level agreement between the Chinese and European space agencies in 2025, the hardware contributions from European institutes have been replaced by domestic Chinese solutions. Consequently, our group’s responsibilities have been redefined during the February 2025 HERD Collaboration meeting in Beijing. We have now moved into a primary role in defining the mission’s scientific program for gamma-ray astronomy, with J. Rico appointed as a member of the HERD Science Working Committee. This shift ensures IFAE will lead the future scientific exploitation of the astronomical data produced by the mission.
Leveraging the experience gained from the HERD project, the group reoriented its hardware efforts toward the characterization and optimization of the Scintillating Fiber Tracker (FIT) for broader space applications. This technology, originally proposed as a joint Swiss-Spanish contribution to HERD, reached a high state of maturity in 2025 through international collaboration with the Ecole Polytechnique de Lausanne and the Université de Genève.
A major milestone was achieved in September 2025 during a beam test campaign at the CERN SPS (see Figure 1). Our group instrumented a seven-layer prototype featuring a 32 × 32 mm2 hodoscope. This setup utilized, for the first time, the 64-channel version of the BETA ASIC developed by the ICCUB, integrated with IFAE’s proprietary trigger and readout electronics. The campaign successfully recorded 150 million proton events and 8 million muon events. This dataset is currently undergoing analysis to evaluate the tracking capabilities, including spatial and angular resolution and momentum estimation via multiple scattering, as a function of the incidence angle.
Parallel to the beam tests, we completed a detailed calibration and optimization campaign at the IFAE laboratories of the FIT readout system using Hamamatsu S13552-10 Silicon Photomultiplier arrays. We characterized essential parameters such as noise levels, linearity, and response times. These results, which form the operational baseline for our system across various experimental conditions, were recently submitted for publication in a technical journal.
Beyond the development of specific mission concepts, the group has maintained a prominent role in large-scale European consortia, notably through the Step-1 proposal for newASTROGAM in response to the ESA M8 call. Within this framework, J. Rico served as the Spanish National Contact Point, coordinating the potential national contribution which centered on the provision of an X-ray coded mask and the associated trigger-readout electronics. While the proposal was not retained for the Step-2 selection phase, our group remains a key participant in the ASTROGAM community, ensuring that the strategic technical expertise developed for this high-priority concept is preserved for future flight opportunities.
To further consolidate our leadership and visibility in a relatively new field for the group, IFAE organized and hosted the second edition of the international conference on Advances in Space AstroParticle Physics (ASAPP2025) in Sant Feliu de Guíxols. Gathering approximately 150 experts, the event was dedicated to reviewing global progress in the design, integration, and testing of instrumentation for the measurement of particles and high-energy radiation in space (see Figure 4).