Advancing Particle Detector Technologies for Space Applications in Astroparticle Physics

Astroparticle physics is experiencing significant growth, particularly with the advent of multi-messenger observations. This rapid expansion has increased the demand for advanced particle detection technologies specifically designed for space applications. Space missions focused on monitoring astrophysical phenomena, such as the Fermi Gamma-ray Space Telescope (Fermi) and the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), underscore the need for efficient, reliable, and versatile experimental setups capable of detecting and analyzing a wide range of cosmic events. Additionally, the growing interest within the scientific community in space weather monitoring, exemplified by projects like the China Seismo-Electromagnetic Satellite (CSES) and the developing Neutrino and Seismic Electromagnetic Signals (NUSES), highlights the critical need for cutting-edge technologies capable of observing Earth electromagnetic and particle environments from space. One of the primary focuses in current astroparticle research is the investigation of dark matter, one of the most profound and unresolved challenges in modern physics. The development of sophisticated satellite-based experiments has been a key driver of progress in this area, with pioneering missions such as the Alpha Magnetic Spectrometer (AMS) and the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) providing crucial insights into the cosmic particle environment. Building on these efforts, several proposed missions, including the High Energy cosmic-Radiation Detection (HERD) and the Antimatter Large Acceptance Detector In Orbit (ALADInO), aim to push the boundaries of dark matter detection and exploration even further. Another critical area in astroparticle physics is the detection of photon polarization in space, a powerful tool for probing high-energy astrophysical processes. Projects such as the Imaging X-ray Polarimetry Explorer (IXPE) are at the forefront of efforts to measure X-ray polarization, providing new insights into the magnetic environments of cosmic sources such as black holes, neutron stars, and supernova remnants. These endeavors are paving the way for more advanced systems capable of exploring photon polarization across a broader range of energies, with significant implications for both fundamental physics and astrophysics. This thesis makes three key contributions to the advancement of particle detector technology for space experiments, each of which is critical for the continued progress of astroparticle physics. The first contribution involves the development of an innovative method for integrating Monolithic Active Pixel Sensors (MAPS) with their associated electronics. This new approach prioritizes minimizing the material budget while enhancing mechanical flexibility, two critical requirements for space-based experiments. The proposed solution is a flexible printed circuit board (PCB) made from Kapton (25 μm thick) and aluminum (20 μm thick), manufactured using a patent-pending method developed in this work. This method is designed for implementation in the silicon-devoted cleanrooms of the Fondazione Bruno Kessler (FBK). This work builds on a previously studied approach used for the Inner Tracking System (ITS1) of the ALICE experiment at CERN in the early 2000s. The key innovation lies in the choice of aluminum over copper, due to aluminum longer radiation length, which reduces material impact on highly- ionizing particles. Additionally, the use of single-point Tape Automated Bonding (spTAB) rather than traditional wire bonding maximizes packaging flexibility. Over the past two decades, continuous progress in PCB manufacturing has led to contemporary machinery that offers numerous advantages and possibilities for further integration of this technology into future experiments. This study represents the initial phase of an R&D project that extends the concepts developed for the ALICE ITS1 experiment by introducing innovative microfabrication techniques. These techniques aim to extend this approach to the entire PCB design, rather than being limited to micro cables, and open the possibility of creating multilayer designs. Preliminary results of integrating this technology with ALPIDE chips are presented in this thesis. The second major contribution of this thesis is the exploration of Lutetium-Yttrium Oxyorthosilicate (LYSO:Ce) detectors for electromagnetic calorimetry in space-based applications. LYSO:Ce detectors are known for their high density, fast response times, and excellent energy resolution, making them particularly well-suited for detecting charged particles and Gamma-Ray Bursts (GRBs). Their properties, such as high light output, compact size, and radiation hardness, make LYSO:Ce crystals an ideal choice for future space missions that require precise measurements of high-energy particles and electromagnetic radiation. This thesis discusses the calibration of these detectors for the second CSES mission, specifically within the High Energy Particle Detector (HEPD-02) payload, along with an analysis of their performance in measuring high-energy photons, such as those emitted by GRBs. The CSES-02 mission aims to enhance our understanding of the interactions between the Earth lithosphere, atmosphere, ionosphere, and magnetosphere by using various instruments to measure the electromagnetic environment at an altitude of approximately 500 km in a Sun-synchronous orbit. The HEPD-02 payload, developed by the Italian LIMADOU collaboration, is designed to measure the flux of protons (30 to 200 MeV) and electrons (3 to 100 MeV) trapped in the Van Allen Belts. The LIMADOU collaboration previously developed a compact electromagnetic calorimeter for the HEPD-01 payload on the CSES satellite, using six LYSO:Ce crystals measuring 5 × 5 × 4 cm3. The HEPD-02 payload incorporates larger LYSO:Ce crystals measuring 15 × 5 × 2.5 cm3, fabricated by Filar OptoMaterials. These crystals, being twice the volume of those used in the previous mission, required advanced fabrication techniques and thorough characterization. This work describes the experimental campaign conducted to study 16 LYSO:Ce crystals and to characterize their properties. The thesis summarizes the main results of this characterization, which are essential to ensure optimal performance under space conditions. The detector module and acquisition system will be sensitive to GRBs with energies above 2 MeV, a range currently covered by experiments like HXMT, Fermi, and INTEGRAL. This work reports on the sensitivity of the HEPD-02 detector to both short and long GRBs, based on tests conducted with an Elekta medical LINAC model SL15, helping to assess the capabilities of HEPD-02 in expanding sky coverage for GRB detection and study. The third advancement presented in this thesis is an innovative microfabrication technique for Gas Electron Multipliers (GEMs), which are crucial for detecting photon polarization in space. GEMs amplify the signals of incoming particles or photons and are vital for high-resolution, low-noise particle detection. The new microfabrication technique aims to enhance GEM performance by improving their reliability and sensitivity for space-based applications. This improvement is especially important for experiments measuring subtle effects, such as photon polarization, which require highly sensitive and precise detection systems. GEM detectors are key to enabling high-resolution X-ray polarization of astrophysical sources when coupled with custom pixel readout ASICs in Gas Pixel Detectors (GPDs), as in the IXPE mission, the Polarlight cubesat pathfinder, and the PFA telescope onboard the future enhanced X-ray Timing and Polarimetry (eXTP) Chinese mission. While the R&D efforts of the IXPE collaboration have led to mature GPD technology, limitations in classical wet-etch or laser-drilled GEM fabrication processes have motivated the exploration of alternative methods. This work investigates a plasma-based etching approach for fabricating GEM patterns at FBK, aiming to improve the aspect ratio of GEM holes and mitigate dielectric charging, which can cause rate- dependent gain changes. Reactive Ion Etching (RIE) enables more vertical etching profiles, resulting in better aspect ratios than traditional wet-etch processes. Additionally, RIE promises to overcome non-uniformities in GEM hole patterns, which are believed to cause systemic effects in the azimuthal response of GPDs equipped with either laser-drilled or wet-etched GEMs. We present a GEM geometry with a 30 μm diameter and a 50 μm pitch, accompanied by extensive characterization (SEM and PFIB) of structural features and aspect ratios. Collaboration with INFN Pisa and Turin allowed for the comparison of electrical properties and the testing of these detectors as electron multipliers in GPDs. Although this R&D is still in its early stages, it holds promise for enhancing the sensitivity of the IXPE mission in X-ray polarimetry measurements by producing GEM patterns with more vertical hole profiles. The outcomes of this study have the potential to advance current technological platforms and improve the capabilities of future space-based X-ray polarimetry missions.