Image shows the detector

Space has always been a privileged observation point for the study of primary cosmic rays and for the investigation of the nature of astrophysical phenomena using gamma rays.

Satellite experiments for cosmic rays and gamma rays need accurate and efficient particle identification and precise reconstruction of the energies and of the directions of incoming particles, which are performed  using different kinds of detectors in synergy.

One of the key elements of these experiments are the tracking systems. In the case of gamma rays, the tracker acts as a converter, allowing to track the charged particles produced in the gamma-ray interactions to reconstruct their arrival direction.

Depending on the experiment energy range target, the tracking system must be optimized to detect the gamma rays either in the pair conversion or in the Compton regime.

Previous experiments, such as COMPTEL and EGRET, exploited the Compton mechanism, while the Fermi-LAT (Large Area Telescope) and DAMPE detect high energy photons exploiting pair conversion.

Their tracking systems are based on single-sided silicon strip detectors.These experiments have led to enormous scientific breakthroughs in recent times.

However, the MeV-GeV gap still remains a poorly covered region of the electromagnetic spectrum. Indeed, many processes at the heart of the extreme Universe have their peak emissivity in this energy range.

The prospect of the 2030s gamma-ray astronomy is to investigate processes in this region. Hence, the challenge for the next generation satellites is to be able to operate in both the Compton and pair conversion regimes.
Experiment proposals such as ASTROGAM and AMEGO are based on double-sided silicon strip detectors.An alternative approach to silicon based detectors is represented by scintillating fiber trackers.

Such designs have been used for more than 30 years, using Photomultiplier Tubes (PMTs) for the readout of scintillation photons. However, thanks to the recent developments on silicon photomultipliers  trackers based on scintillation fibers now represent a valuable alternative option for satellite experiments.  

The tracking systems of the Advanced Particle-astrophysics Telescope (APT) and of the NUSES mission are based on scintillating fibers with SiPM readout. In this presentation the contribution of the INFN to the APT and the NUSES missions will be illustrated.

The NUSES mission is a pathfinder satellite for new technologies for astroparticle physics. Its main goal is the development of new observational techniques, sensors and related electronics and data acquisition systems for satellite platforms. The INFN is involved in the design of a compact scintillation fiber tracker with SiPM array readout.

The main R&D activities consist in the mechanical design, performance simulation, and DAQ electronics design. A prototype has been built and tested at the CERN PS facilty with an electron-pion beam. The preliminary results will be illustrated.The design of the APT experiment is based on  active Imaging Compton Converter (ICC) layers  alternated with scintillating fiber tracker layers.

The ICC tracker-converter module consists of a crystal scintillator layer coupled with external wavelength shifting (WLS) fibers, readout with SiPMs. The tracker modules are also made of scintillation fibers, readout with SiPMs.

The main contributions of the INFN in the ADAPT experiment, a balloon flight APT design demonstrator, is the application of the SMART asic (originally developed for the Cherenkov Telescope Array) for the SiPM readout.

Tests have been performed on a prototype, as well as performance simulation activities. 

Relatore: Roberta Pillera

Data: 03/02/2022