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The γ -ray blazars B2 1811+31 and GB6 J1058+2817 exhibited strong flaring activity in 2020 and 2021, respectively. These high states were observed by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope in the high-energy (HE; 100 MeV < E < 100 GeV) γ -ray band, triggering observations in the very-high-energy (VHE, E > 100 GeV) γ -ray band with the MAGIC telescopes, in UV and X rays with the Neil Gehrels Swift Observatory and in the radio and optical bands with many ground-based telescopes. MAGIC telescopes observations led to the first detection at VHE of both sources. In this contribution, we present the details of these detections and the results of an extensive study of the high-state properties of the two blazars. Fermi -LAT data were used to derive long-term γ -ray light-curves and identify the periods of enhanced activity in both sources. We investigated their spectral properties and temporal variability, with focus on how the strong spectral hardening and the variability timescale can provide information on the γ -ray emitting regions during the flare.

Gamma-ray spectroscopy and dosimetry are complementary techniques used to locate and identify radioactive sources containing gamma-ray-emitting radioisotopes. Gamma-ray spectroscopy is extensively studied for various applications across multiple fields, including homeland security, environmental radioactivity monitoring, tackling illegal trade of radioiso-topes, and medical sciences. Introducing our newly established startup, Flying DEMon s.r.l., comprised of young researchers, academic professors, and backed by university support. Our venture aims to advance project development, leveraging the grant awarded through the E-TEC2 contest initiated by ENAC. The team will showcase their comprehensive work plan, highlighting the project’s competitiveness and self-sustaining potential. The objective of our startup is to harness cutting-edge technologies in the field of gamma spectroscopy and dosimetry, adaptable for deployment via Unmanned Aircraft Systems (UAS). This innovation holds significant promise for environmental monitoring, facilitating tasks such as pinpointing widespread radioactive sources or identifying concealed and hard-to-reach nuclear waste. Additionally, this advancement holds potential for applications in military, security, and industrial oversight. Our research focus primarily revolves around real-time and rapid gamma-ray analysis in open-field environments. Our group not only supports the core project objectives but also enables its applicability in diverse and non-traditional sectors, such as Agritech.

Gamma-ray spectroscopy and gamma-ray imaging are two complementary techniques used for the localization and the identification of radioactive sources containing gamma-ray emitting radioisotopes. The radioactivity monitoring is focused on the detection of both artificial and environmental radioactive sources like Naturally Occurring Radioactive Materials (NORM). This kind of contamination becomes dangerous when the detection of the unwanted substances exhibits a concentration significantly above the environmental radioactive background radiation levels. For this purpose, we have developed, tested and shown a High Efficiency fast-Response GAmma (HERGA) detector useful for the identification of radionuclides and for gamma-ray imaging. A first version of the gamma detector prototype was composed of 16 CsI(Tl) scintillating crystals of 3x3x10 cm3 size, arranged in 4x4 matrix coupled with standard Photomultiplier tubes (PMTs). An image reconstruction of a radioactive gamma emitter source is possible using the coded mask technique, in which a 7x7 mask, made of Plastic and Tungsten tiles, is placed in front of the detector and a pattern recognition algorithm based on classical statistical methods (Kolmogorov Smirnov) is used to reconstruct the source position. The measurements carried out showed a point spread function (PSF) of a few mrad for pointlike sources. The Minimum Detectable Activity (MDA) was also determined in the case of pointlike radioactive sources. In this contribution we will present an update of the HERGA detector prototype in which Silicon Photomultipliers (SiPMs) are used in place of the PMTs. SiPMs provide similar or even better performance compared to the standard PMT sand provide benefits in terms of lower power consumption and reduced cost and compactness. The advantages of the SiPM technology are also characterized by the robustness of the photosensor that makes the new prototype compact, portable, ideal for in-situ and real-time. We will show a comparison between the results obtained with the newest SiPM read-out technology with respect to those obtained with the PMT one, in terms of energy and spatial resolution. The imaging performance is also in phase of testing in order to localize extended radioactive sources such as for example NORM samples or to detect inaccessible or hidden nuclear waste.

Satellite experiments for gamma-ray and cosmic-ray detection employ plastic scintillators to discriminate charged from neutral particles in order to correctly identify gamma-rays and charged nuclei. The High Energy Cosmic Radiation Detection (HERD) facility will be among these experiments, to be installed onboard the future Chinese Space Station (CSS), to detect cosmic-rays and gamma-rays up to TeV energies. The plastic scintillator detector (PSD) will consist of scintillator tiles or bars coupled to Silicon Photomultipliers (SiPMs). To discriminate gamma-rays from charged particles and measure the ion charge up to iron nuclei a wide dynamic range is required, from few tens up to thousands of photoelectrons. We have equipped a plastic scintillator tile prototype with SiPMs produced by Hamamatsu and AdvanSiD and coupled their analog signals to the DT5550W board based on the CITIROC ASIC, produced by CAEN SpA. The CITIROC ASIC allows both the formation of a fast trigger with a configurable threshold and the digitization of analog waveforms after a preamplification and shaping stage along two paths with different gain settings. The performance of our prototype will be shown.

The High Energy Cosmic Radiation Detection (HERD) facility, onboard the future China’s Space Station (CSS), will provide high quality data on charged cosmic rays and gamma rays in the energy range from few GeV to PeV. HERD will be equipped with a fine granularity cubic crystals calorimeter and a precision tracker detector. The entire instrument will be surrounded by a Plastic Scintillator Detector (PSD) that will be used to discriminate charged from neutral particles in order to correctly identify gamma-rays and nuclei. One proposed configuration for the HERD PSD consists of tiles of plastic scintillator, optically coupled to SiPMs. In 2019-2020, two beam tests were performed at CNAO (Centro Nazionale di Adroterapia Oncologica) in Pavia (Italy), exposing some PSD tiles, equipped with SiPMs, to low-beta p and C ion beams in order to evaluate the detector response to heavy ions. Spatial and temporal resolution were also evaluated using a radioactive source.

Plastic scintillators are widely used for anti-coincidence systems and for the identification of charged cosmic-ray nuclei in satellite experiments. For this reason, a plastic scintillator detector (PSD) should have a high detection efficiency for charged cosmic rays and a very good capability of measuring charges. We implemented a full and customizable simulation tool to investigate the performance of a PSD coupled to Silicon Photomultipliers. The overall performance of the detector is studied by tracking optical photons produced inside the scintillator. The simulation will be used for the design of a PSD for future space experiments, such as HERD, AMEGO, e-Astrogam. In this work we investigated in detail the effect of Birks’ saturation in the discrimination of charged ions up to iron nuclei. We will show the comparison between simulations and measurements conducted on prototype scintillator tiles.

Current gamma-ray and cosmic-ray satellite experiments employ plastic scintillators to discriminate charged and neutral particles and to identify nuclei. Scintillators are commonly read out using the classical photomultiplier tubes (PMTs). Recent measurements and R& D projects are demonstrating that Silicon Photomultipliers (SiPMs) are suitable for the detection of fast light signals with resolution up to the single photoelectron, with a lower power consumption. For these reasons, next generation missions are planning to replace PMTs with SiPMs. We tested a prototype plastic scintillator tile, equipped with a set of SiPMs and studied its response to a beam of electrons and pions at CERN. We used Near Ultraviolet (NUV) SiPMs of 1x1 mm2 and 4x4 mm2 area, placed along the edges of the tile. The tile was irradiated in different positions in order to study the dependence of the collected light on the impact point of the beam particles. We also varied the energy of the beam in order to study how this parameter affects the amount of collected light.

Silicon Photomultipliers (SiPMs) are excellent devices to detect the faint and short Cherenkov light emitted in high energy atmospheric showers, and therefore suitable for use in imaging air Cherenkov Telescopes. The high density Near Ultraviolet Violet SiPMs (NUV-HD3) produced by Fondazione Bruno Kessler (FBK) in collaboration with INFN were used to equip optical modules for a possible upgrade of the Schwarzschild-Couder Telescope camera prototype, in the framework of the Cherenkov Telescope Array project. SiPMs are 6×6 mm 2 devices based on 40×40 μm 2 microcells optimized for photo-detection at the NUV wavelengths. More than 40 optical modules, each composed by a 4×4 array of SiPMs, were assembled. In this contribution we report on the development and on the assembly of the optical modules, their validation and integration in the camera.

Long-duration [gamma]-ray bursts (GRBs) are the most luminous sources of electromagnetic radiation known in the Universe. They arise from outflows of plasma with velocities near the speed of light that are ejected by newly formed neutron stars or black holes (of stellar mass) at cosmological distances.sup.1,2. Prompt flashes of megaelectronvolt-energy [gamma]-rays are followed by a longer-lasting afterglow emission in a wide range of energies (from radio waves to gigaelectronvolt [gamma]-rays), which originates from synchrotron radiation generated by energetic electrons in the accompanying shock waves.sup.3,4. Although emission of [gamma]-rays at even higher (teraelectronvolt) energies by other radiation mechanisms has been theoretically predicted.sup.5-8, it has not been previously detected.sup.7,8. Here we report observations of teraelectronvolt emission from the [gamma]-ray burst GRB 190114C. [gamma]-rays were observed in the energy range 0.2-1 teraelectronvolt from about one minute after the burst (at more than 50 standard deviations in the first 20 minutes), revealing a distinct emission component of the afterglow with power comparable to that of the synchrotron component. The observed similarity in the radiated power and temporal behaviour of the teraelectronvolt and X-ray bands points to processes such as inverse Compton upscattering as the mechanism of the teraelectronvolt emission.sup.9-11. By contrast, processes such as synchrotron emission by ultrahigh-energy protons.sup.10,12,13 are not favoured because of their low radiative efficiency. These results are anticipated to be a step towards a deeper understanding of the physics of GRBs and relativistic shock waves.

The Cherenkov Telescope Array (CTA) is the next-generation ground-based observatory for very-high-energy gamma-ray astronomy. An innovative 9.7 m aperture, dual-mirror Schwarzschild-Couder Telescope (SCT) design is a candidate design for CTA Medium-Sized Telescopes. A prototype SCT (pSCT) has been constructed at the Fred Lawrence Whipple Observatory in Arizona, USA. Its camera is currently partially instrumented with 1600 pixels covering a field of view of 2.7 degrees square. The small plate scale of the optical system allows densely packed silicon photomultipliers to be used, which combined with high-density trigger and waveform readout electronics enable the high-resolution camera. The camera's electronics are capable of imaging air shower development at a rate of one billion samples per second. We describe the commissioning and performance of the pSCT camera, including trigger and waveform readout performance, calibration, and absolute GPS time stamping. We also present the upgrade to the camera, which is currently underway. The upgrade will fully populate the focal plane, increasing the field of view to 8 degree diameter, and lower the front-end electronics noise, enabling a lower trigger threshold and improved reconstruction and background rejection.