Trento Institute for Fundamental Physics and Applications

SARA is the system of plastic scintillators coupled with silicon photomultipliers that will take part in the AEgIS experiment at CERN, measuring the time-of-flight of antihydrogen as it falls through a moiré deflectometer. Its development focused on simplicity, versatility and economy of the design and was supported by both physical tests and numerical simulations. The instrument structure pairs the utilization of the scintillators as structural components with custom made 3D printed corner elements and the electronics allows selection between coincidence discrimination made on each scintillator and made between different scintillators.

Precise tracking in space and time is becoming a more and more pivotal ingredient in designing high-energy physics experiments. Low-Gain Avalanche Diodes (LGADs) with an active thickness of ∼ 50 μm have proved the ability of silicon sensors to provide precise timing down to about 30 ps. At present, this timing performance is maintained almost unchanged up to a fluence of 2.5 × 1015 n 1MeV eq./cm2.Thinner substrates can further improve the timing resolution and the radiation tolerance of the LGAD sensors.At the end of 2022, FBK released a batch of thin LGAD sensors with an active thickness between 15 and 45 μm to investigate the effect of the thickness in improving sensor performances.A new design of the sensor layout and periphery has been studied and manufactured, optimised for the sensor thickness and the requirement to withstand high electric fields up to very high fluences.The state-of-the-art design of the LGAD gain implant from FBK has been used on thin substrates, exploiting the concurrent implantation of boron and carbon atoms in the multiplication region typical of LGAD sensors. This resulted in the most radiation-tolerant LGADs ever produced by FBK.The electrical characterisation of sensors before and after irradiation, together with the analysis of the signals from laser stimulus and charged particles, will be presented. The impact of the sensor thickness on the collected charge and the timing resolution will be explored and discussed.

We present the first measurement of cosmic-ray fluxes of ^{6} Li and ^{7} Li isotopes in the rigidity range from 1.9 to 25GV. The measurements are based on 9.7×10^{5} ^{6} Li and 1.04×10^{6} ^{7} Li nuclei collected by the Alpha Magnetic Spectrometer on the International Space Station from May 2011 to October 2023. We observe that over the entire rigidity range the ^{6} Li and ^{7} Li fluxes exhibit nearly identical time variations and, above ∼4 GV, the time variations of ^{6} Li, ^{7} Li, He, Be, B, C, N, and O fluxes are identical. Above ∼7 GV, we find an identical rigidity dependence of the ^{6} Li and ^{7} Li fluxes. This shows that they are both produced by collisions of heavier cosmic-ray nuclei with the interstellar medium and, in particular, excludes the existence of a sizable primary component in the ^{7} Li flux.

We present results over an 11-year Solar cycle of cosmic antiprotons based on 1.1×10^{6} events in the rigidity range from 1.00 to 41.9GV. The p[over ¯] fluxes exhibit distinct properties. The magnitude of the p[over ¯] flux temporal variation is significantly smaller than those of p, e^{-}, and e^{+}. A hysteresis between the p[over ¯] fluxes and the p fluxes is observed, whereas the p[over ¯] and e^{-} fluxes show a linear correlation. With a model-independent analysis, we found a universal relation between the shape of the rigidity spectrum and the magnitude of flux temporal variation over an 11-year Solar cycle for both positively and negatively charged particles. The simultaneous results on p[over ¯] and p, e^{-}, and e^{+} provide unique information for understanding particle transport in the Solar System as a function of mass, charge, and spectral shape.

Machine learning (ML) models are able to process complex images, providing state-of-the-art performance in tasks such as image classification and semantic segmentation. These models can be mapped to highly efficient commercial-off-the-shelf (COTS) specialized hardware accelerators, whose reliability should be carefully evaluated before deployment. Unfortunately, given the large number of ML model architectures, possible configurations or input selections, and the numerous COTS accelerator architectures available, exhaustively testing every model-accelerator combination with beam experiments is unfeasible. Additionally, the radiation data obtained with a specific combination can hardly be extended to different configurations. In this paper, we test vision transformer (ViT) and segmentation convolutional neural network (CNN) models, in addition to several ML micro-benchmarks, on the Google Coral Edge TPU at 6 different radiation facilities, investigating particle-, software-, and hardware-dependent reliability behaviors. Our experimental results show that, while the cross section for radiation-induced silent data corruption (SDCs) can be up to 8 orders-of-magnitude higher when testing with high-LET heavy ions compared to atmospheric neutrons, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">characteristics</i> of the SDCs are similar across all types of radiation tested. Instead, the most impactful factors that lead to misclassifications in beam tests are actually the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">model complexity</i> and the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">input selection</i>. These results can be leveraged to more efficiently plan and utilize the beam time available in radiation experiments, thus improving the understanding of the fault models affecting the software, while also characterizing the reliability of the underlying hardware accelerator.

The High-Energy Particle Detector (HEPD-02) is one of the scientific payloads of the China Seismo-Electromagnetic Satellite (CSES-02). The HEPD-02’s main purpose is to characterize the particle environment in the Earth’s vicinity, identifying sudden changes in the fluxes and correlating them with solar and terrestrial phenomena. Additionally, HEPD-02 also has capabilities in detecting Gamma-Ray Bursts. At the core of HEPD-02, a tower of scintillation counters made of plastic and LYSO crystals is able to recognize electrons in the range between 3 and 100 MeV, protons and nuclei between 30 and 200 MeV/n. Plastic scintillators covering the calorimeter on five sides allow to reject particles entering from the top and not completely absorbed within its volume. In this work, the design of the HEPD-02 is reviewed in comparison to its predecessor, HEPD-01, highlighting the innovations of the new design. The design of each scintillation counter type has been fully validated through a campaign of prototype realization, testing, and characterization. The production of the scintillation counters, including the PMT selection process, is also discussed. Finally, the performance of the counters is compared with simulations, showing an agreement of within 20% with the expected performance, thereby meeting expectations.

The tilt-to-length coupling during the LISA Pathfinder mission has been numerically and analytically modeled for particular time spans. In this work, we investigate the long-term stability of the coupling coefficients of this noise. We show that they drifted slowly (by 1 μm/rad and 6×10−6 in 100 days) and were strongly correlated to temperature changes within the satellite (8 μm/rad/K and 30×10−6/K). Based on analytical tilt-to-length coupling models, we attribute the temperature-driven coupling changes to rotations of the test masses and small distortions in the optical setup. Particularly, our findings lead to the conclusion that LISA Pathfinder’s optical baseplate was bent during the cooldown experiment, which started in late 2016 and lasted several months. Published by the American Physical Society 2024