Pixellated scintillation detectors have the potential to overcome several limitations of conventional microchannel-plate-based detectors employed in time-of-flight mass spectrometry (ToF-MS), such as extending detector lifetime, reducing vacuum requirements, or increasing the ion throughput. We have developed a prototype comprising a fast organic scintillator (Exalite 404) coupled to an array of 16 silicon photomultipliers (SiPMs), with read-out electronics based on the FastIC application-specific integrated circuit (ASIC). Each SiPM signal processed by FastIC is fed into its own time-to-digital converter (TDC). The dead time of a single channel can be as short as ∼20 ns. As a result, our system have the potential to process ion rates above 109 cm−2 s−1. We have evaluated the performance of our prototype using a velocity-map imaging ToF-MS instrument, recording the time-of-flight mass spectra of C3H6 and CF3I samples. We achieved time resolutions of (3.3±0.1) and (2.5±0.2) ns FWHM for ions of mass-to-charge ratio (m/z) values of 196 and 18, respectively. This corresponds to a mass resolution of ∼1000 for m/z<200, which we found to be dominated by the spread in ion arrival times.

Most single-photon emission computed tomography (SPECT) scanners employ a gamma camera with a large scintillator crystal and 50–100 large photomultiplier tubes (PMTs). In the past, we proposed that the weight, size and cost of a scanner could be reduced by replacing the PMTs with large-area silicon photomultiplier (SiPM) pixels in which commercial SiPMs are summed to reduce the number of readout channels. We studied the feasibility of that solution with a small homemade camera, but the question on how it could be implemented in a large camera remained open. In this work, we try to answer this question by performing Geant4 simulations of a full-body SPECT camera. We studied how the pixel size, shape and noise could affect its energy and spatial resolution. Our results suggest that it would be possible to obtain an intrinsic spatial resolution of a few mm FWHM and an energy resolution at 140 keV close to 10%, even if using pixels more than 20 times larger than standard commercial SiPMs of 6 × 6 mm2. We have also found that if SiPMs are distributed following a honeycomb structure, the spatial resolution is significantly better than if using square pixels distributed in a square grid.

Silicon photomultipliers (SiPMs) have the potential to be particularly suitable for space applications, where weight, volume and power consumption are strongly constrained. The SiPM signals recorded on board satellites, balloons or drones must be processed and digitized minimizing the size, cost and power consumption of the electronics. In this context we developed the BETA ASIC, a radiation-tolerant chip designed to amplify, shape and digitize the signal of up to 64 channels, with a power consumption of $\sim 1 \mathrm{~mW}$/channel. The ASIC provides a dual gain path, which allows resolving single-photoelectron (single-phe) events and achieving a large dynamic range of a few thousand phes. Each gain path can also be adjusted in order to optimize the ASIC performance for a given SiPM or application. BETA also provides a trigger output, with which it is possible to time tag events of a few phes with $\lt 1 \mathrm{~ns}$ resolution. We developed two different versions of the chip: BETA-64, which has 64 input channels; and BETA-16, in which each of the 16 inputs channels has its own trigger output, which can then be combined to define a more complex coincidence trigger logic. In this contribution we describe the main characteristics of the ASIC and the evaluation of its performance. We also introduce a few examples of applications planning to employ the BETA, like the development of a radiation monitor for ESA’s LISA large space mission.

Time of Flight positron emission tomography (TOF-PET) scanners demand electronics that are power-efficient, low-noise, cost-effective, and possess a large bandwidth. Recent developments have demonstrated sub-100 ps time resolution with elevated power consumption per channel, rendering this unfeasible to build a scanner. In this work, we evaluate the performance for the TOF-PET of the FastIC front-end using different scintillators and silicon photomultipliers (SiPMs). FastIC isan eight-channel application specific integrated circuit developed in CMOS 65 nm capable of measuring the energy and the arrival time of a detected pulse with 12 mW per channel. Using Hamamatsu SiPMs (S13360-3050PE) coupled to LSO:Ce:0.2%Cacrystals of 2x2x3mm3and LYSO:Ce:0.2%Ca of 3.13x3.13x20 mm3, we measured a coincidence time resolution (CTR) of(95 +/- 3) and 156 +/- 4) ps full width half maximum (FWHM),respectively. With Fondazione Bruno Kessler NUV-HD LF2 M0SiPMs coupled to the same crystals, we obtained a CTR of(76 +/- 2) and (127 +/- 3) ps FWHM. We employed FastIC with a TlCl pure Cherenkov emitter, demonstrating time resolutions comparable to those achieved with the high-power-consuming electronics. These findings shows that the FastIC represents a cost-effective alternative that can significantly enhance the time resolution of the current TOF-PET systems while maintaining low power consumption

In recent years, the MAGIC telescopes have been equipped with a setup that allows its Imaging Atmospheric Cherenkov Telescopes (IACTs) to function as an Intensity Interferometer. The deadtime-free setup includes a 4-channel GPU-based real-time correlator together with optical filters in the 350-450 nm wavelength range and specialized Active Mirror Control (AMC) configurations. This implementation allows MAGIC to perform measurements of the spatial coherence (visibility) of the intensity fluctuations of an object’s starlight over several separations (baselines) and construct a model of said object. The accessible baseline range for MAGIC is ~40-90 m which translates into an angular resolution of 0.5-1 mas. Additionally, thanks to the AMC it can access even smaller baselines, of less than 17 m (which is the diameter of each of both dishes) to measure objects of greater angular size (>1 mas) and even measure the zero-baseline correlation, which is key to calibrate the system. We present the latest measurements that allow us to understand the performance and systematics of our setup and validate our analysis.

The small sensitive area of commercial silicon photomultipliers (SiPMs) is often the main limitation for their use in experiments and applications that require large detection areas. Since capacitance, dark count rate and cost increase with the SiPM size, they are rarely found in sizes larger than 6 × 6 mm2. Photo-Trap combines a wavelength-shifter plastic, a dichroic filter and a standard commercial SiPM to build pixels of a few cm2. With this approach it can collect light over an area that can be ∼10–100 times larger than the area of a commercial SiPM, while keeping the noise, single-photoelectron resolution, power consumption and likely the cost of a single small SiPM. We developed four different proof-of concept pixels sensitive in the near UV band, the largest one being of 40 × 40 mm2. We characterized them through laboratory measurements and Geant4 simulations. The optical gain we measured with the prototypes went from ∼5 to ∼15, while the single-photon time resolution was of ∼3–5 ns FWHM. With the achieved performance Photo-Trap could be a competitive low-cost alternative for applications that require photosensors with large collection areas and low noise, such as dark matter experiments and optical wireless communication.

The High Energy cosmic-Radiation Detection (HERD) facility onboard the Chinese Space Station will provide high quality data on charged cosmic rays from few GeV to PeV energies and gamma rays above 100 MeV. HERD will employ a Plastic Scintillator Detector (PSD) to discriminate charged from neutral particles to help identify gamma rays and to measure the nuclei charge up to iron. For these reasons, the HERD PSD needs to have high detection efficiency ($\sim99.998\%$) and a good charge resolution ($\sim30\%$ at low $Z$). During 2022 and 2023, beam test campaigns were performed at CERN and at CNAO (Centro Nazionale di Adroterapia Oncologica) in Italy, aimed at studying the overall performance of the PSD detector. A prototype detector composed of 8 plastic scintillator trapezoidal bars of two different lengths was equipped with Silicon Photomultipliers (SiPMs) arranged in different positions along the bars. We tested SiPM of different sizes to increase the dynamic range and study the charge resolution in the range of Z between 1 and $\sim26$. The prototype was irradiated with relativistic protons and pions at CERN PS, an ion beam at CERN SPS and with low momentum protons and C ions (with energy release similar to those of high-Z relativistic particles) at CNAO. In this work we present and compare the results from these campaigns. Moreover, we present a characterization of plastic scintillator detectors for the future generation of space missions, with respect to their capabilities for nuclei identification, in terms of quenching effects.

Positron emission tomography (PET) has become standard practice in many clinical applications including oncology, cardiology and neurology. Recent developments in PET scanners have pushed the limits of these applications, thanks to long axial field of view scanners which can improve system sensitivity and the use of time-of-flight (TOF) information which can improve spatial resolution. However, the cost and space requirements for total-body PET systems has created a need for flexible, low-cost yet high-sensitivity systems with large axial field of view. Additionally, currently achievable TOF resolutions (around 200 ps for current clinical scanners) limit the gains in image resolution. In this work, we present the first reconstructions for a flexible two-panel ultra-high TOF resolution PET system expected to achieve 75 ps full-width at half maximum (FWHM). The scanner relies on pixelated L(Y)SO scintillators with novel detectors with dual readout measuring depth-of-interaction (DOI) information. The performance of the new system is demonstrated on Monte-Carlo simulations of an anthropomorphological numerical phantom reconstructed using a newly developed TOF+DOI-enabled reconstruction engine. The presented reconstructions exhibit high image quality, demonstrating the promise of the proposed PET system.

The shift towards early diagnosis and prevention in medicine necessitates high-performing PET imaging systems with improved sensitivity and specificity. To achieve this, additional time-of-flight measurements in PET enhance the signal-to-noise ratio and enable the construction of better-performing systems. However, the timing resolution of PET systems is limited by several factors, such as slow scintillation response time, optical photon travel time spread, number of detected scintillation photons, and timing precision of the photo-sensor and fast readout electronics. Although there have been efforts to develop new scintillators for PET, this contribution focuses on optimizing photo sensors and readout electronics. The authors integrated high-performing HD-NUV-MT silicon photomultipliers from FBK with novel low-power FastIC ASICs for fast-timing applications. They constructed a pair of 16-channel gamma detector modules and placed them in a coincidence setup, demonstrating very high coincidence timing resolution below 100 ps FWHM. This achievement enables the construction of high-performing PET detectors with incomplete sampling and simplified systems consisting of flat panel detectors that can be easily combined in larger systems. The authors simulated the performance of an imager comprising two 120 cm × 60 cm panels of segmented 20 mm thick LYSO crystal arrays read by dual-sided readout with fast timing and imaged a human XCAT phantom. They demonstrated that such a system, consisting of much less scintillator material compared to a total body PET imager with a standard opening, exhibits excellent performance. Overall, this approach provides a promising path toward developing highly sensitive and specific PET imaging systems that can aid in early disease diagnosis and prevention.

Satellite experiments employ plastic scintillators to discriminate charged from neutral particles and to identify charged nuclei. We have assembled and tested a prototype of Plastic Scintillator Detector (PSD) equipped with Silicon Photomultipliers (SiPMs) for the High Energy Cosmic Radiation Detection facility (HERD) that will be installed onboard the future Chinese Space Station (CSS). The HERD experiment will provide high quality data on charged cosmic rays up to PeV energies and gamma rays above 100 MeV energies. In order to explore the capability of charge identification of nuclei up to iron, a beam test campaign was performed in 2022 at CERN to study the overall performance of the PSD. The PSD prototype is composed of 8 plastic scintillator trapezoidal bars of two different lengths. The PSD prototype was irradiated with an ion beam composed of particles of selected momentum of 150 GeV/n at CERN SPS H8 beam line. Along the beam line two 10× 10× 0.5 cm3 squared plastic scintillator tiles were also placed to monitor the beam composition and the particle fragmentation upstream and downstream the beam line. In this work the main results of the SPS H8 beam test in terms of nuclei identification performances of the PSD ptototype detector will be shown.

We present here a unified scenario that connects three peculiar spectral features recently reported in the spectra of charged cosmic rays (CRs). The spectral hardening measured by AMS-02 in the hadronic spectra above similar to 250 GeV is here interpreted as a diffusion imprint, and modeled by means of a transport coefficient that smoothly hardens with rigidity. We implement such propagation framework to solve the transport equation with the DRAGON2 numerical code in order to determine the large-scale contribution to the CR fluxes. On top of this solution we explore the hypothesis of a nearby, hidden Supernova Remnant (SNR) to be responsible for the high-energy (above similar to 100 GeV) all-lepton flux, in particular for the spectral break consistently measured by all the space- and ground-based detectors around 1 TeV. We compute such contribution analytically adopting the same propagation setup implemented for the large-scale background. Simultaneously, we find the signature of the same source in the peculiar bump structure observed by the DAMPE Collaboration in the proton spectrum, consisting of a strong hardening at similar to 500 GeV and a softening at 13 TeV. We validate our hypothesis with the CR dipole-anisotropy (DA) amplitude and phase. In particular, we interpret the high-energy data (above 10 TeV) pointing towards the Galactic Center as the convolution of the directional fluxes of the large-scale-background sources, whereas the DA amplitude below that energy is compatible with the predictions of our model and is therefore considered as a signature of the nearby SNR that we invoke.

A standard camera for Single Photon Emission Computed Tomography (SPECT) contains 50-100 photomultiplier tubes (PMTs) that occupy at least 50% of its volume. It is shielded by a thick layer of lead which makes it heavy and bulky. Replacing PMTs by silicon photomultipliers (SiPMs) could significantly reduce the weight and size of a SPECT camera. However, the main obstacle is the limited size of SiPMs: even with the largest commercially available SiPM of 6 x 6 mm(2) a few thousand channels would be needed to fill a camera. As a solution, we propose to use Large Area SiPM Pixels (LASiPs) which are built by summing the currents of several SiPMs into a single output. We developed a LASiP prototype summing 8 SiPMs using the MUSIC ASIC. To test the feasibility of using this solution in SPECT, we built a proof-of-concept micro camera that consisted of four of our LASiP prototypes coupled to a 40 x 40 x 8 mm(3) NaI(Tl) crystal. We were able to reconstruct simple images of a Tc-99m capillary with an intrinsic spatial resolution of similar to 2mm and an energy resolution of similar to 11.6%. We also simulated the system with Geant4, finding a good agreement with our experimental results. The simulations were extended to a larger camera, aiming to study the impact of pixel size, shape and noise.

Single Photon Emission Computed Tomography (SPECT) scanners based on photomultiplier tubes (PMTs) are still largely employed in the clinical environment. A standard camera for full-body SPECT employs ~50-100 PMTs of 4-8 cm diameter and is shielded by a thick layer of lead, becoming a heavy and bulky system that can weight a few hundred kilograms. The volume, weight and cost of a camera can be significantly reduced if the PMTs are replaced by silicon photomultipliers (SiPMs). The main obstacle to use SiPMs in full-body SPECT is the limited size of their sensitive area. A few thousand channels would be needed to fill a camera if using the largest commercially-available SiPMs of 6 × 6 mm2. As a solution, we propose to use Large-Area SiPM Pixels (LASiPs), built by summing individual currents of several SiPMs into a single output. We developed a LASiP prototype that has a sensitive area 8 times larger than a 6 × 6 mm2 SiPM. We built a proof-of-concept micro-camera consisting of a 40 × 40 × 8 mm3 NaI(Tl) crystal coupled to 4 LASiPs. We evaluated its performance in a central region of 15×15 mm2, where we were able to reconstruct images of a 99mTc capillary with an intrinsic spatial resolution of ~2 mm and an energy resolution of ~11.6% at 140 keV. We used these measurements to validate Geant4 simulations of the system. This can be extended to simulate a larger camera with more and larger pixels, which could be used to optimize the implementation of LASiPs in large SPECT cameras. We provide some guidelines towards this implementation.

In this work we aim at reproducing, simultaneously, the spectral feature at $\sim 10 \, \mathrm{TeV}$ in the cosmic-ray proton spectrum, recently reported by the DAMPE Collaboration, together with the spectral break at $\sim 1 \, \mathrm{TeV}$ measured by H.E.S.S. in the lepton spectrum. Those features are interpreted as signatures of one nearby hidden cosmic-ray accelerator. We show that this interpretation is consistent with the dipole-anisotropy data as long as the rigidity scaling of the diffusion coefficient features a hardening at $\sim 200 \, \mathrm{GV}$, as suggested by the light-nuclei data measured with high accuracy by the AMS-02 Collaboration. Such rigidity-dependent diffusion coefficient is applied consistently to the large-scale diffuse cosmic-ray sea as well as to the particles injected by the nearby source.

In the last ten years silicon photomultipliers (SiPMs) have gained terrain in experiments and applications in which photomultiplier tubes have been the dominant photosensors during decades. Imaging Atmospheric Cherenkov Telescopes (IACTs) for very high energy (VHE, E>50 GeV) gamma-ray astronomy are experiencing the same process. Until now FACT was the only IACT using SiPMs. In the Cherenkov Telescope Array (CTA), the next-generation VHE gamma-ray observatory, at least 70 telescopes equipped with SiPMs are planned to be built. The first prototypes have already been constructed and are now being commissioned. Here we discuss some of the advantages and drawbacks of using SiPMs in VHE gamma-ray astronomy and provide a brief overview of different developments related to the use of SiPMs in IACTs.

Aims. We measure the Crab Nebula γ-ray spectral energy distribution in the ~100 TeV energy domain and test the validity of existing leptonic emission models at these high energies.Methods. We used the novel very large zenith angle observations with the MAGIC telescope system to increase the collection area above 10 TeV. We also developed an auxiliary procedure of monitoring atmospheric transmission in order to assure proper calibration of the accumulated data. This employs recording optical images of the stellar field next to the source position, which provides a better than 10% accuracy for the transmission measurements.Results. We demonstrate that MAGIC very large zenith angle observations yield a collection area larger than a square kilometer. In only ~ 56 h of observations, we detect the γ-ray emission from the Crab Nebula up to 100 TeV, thus providing the highest energy measurement of this source to date with Imaging Atmospheric Cherenkov Telescopes. Comparing accumulated and archival MAGIC and Fermi/LAT data with some of the existing emission models, we find that none of them provides an accurate description of the 1 GeV to 100 TeV γ-ray signal.

Aims. In the presence of a sufficient amount of target material, gamma-rays can be used as a tracer in the search for sources of Galactic cosmic rays (CRs). Here we present deep observations of the Galactic center (GC) region with the MAGIC telescopes and use them to infer the underlying CR distribution and to study the alleged PeV proton accelerator at the center of our Galaxy.Methods. We used data from approximate to 100 h observations of the GC region conducted with the MAGIC telescopes over five years (from 2012 to 2017). Those were collected at high zenith angles (58-70 deg), leading to a larger energy threshold, but also an increased effective collection area compared to low zenith observations. Using recently developed software tools, we derived the instrument response and background models required for extracting the diffuse emission in the region. We used existing measurements of the gas distribution in the GC region to derive the underlying distribution of CRs. We present a discussion of the associated biases and limitations of such an approach.Results. We obtain a significant detection for all four model components used to fit our data (Sgr A*, "Arc", G0.9+0.1, and an extended component for the Galactic Ridge). We observe no significant difference between the gamma-ray spectra of the immediate GC surroundings, which we model as a point source (Sgr A*) and the Galactic Ridge. The latter can be described as a power-law with index 2 and an exponential cut-off at around 20 TeV with the significance of the cut-off being only 2 sigma. The derived cosmic-ray profile hints to a peak at the GC position and with a measured profile index of 1.2 +/- 0.3 is consistent with the 1/r radial distance scaling law, which supports the hypothesis of a CR accelerator at the GC. We argue that the measurements of this profile are presently limited by our knowledge of the gas distribution in the GC vicinity.

M87 is one of the closest (z=0.00436) extragalactic sources emitting at very-high-energies (VHE, E > 100 GeV). The aim of this work is to locate the region of the VHE gamma-ray emission and to describe the observed broadband spectral energy distribution (SED) during the low VHE gamma-ray state. The data from M87 collected between 2012 and 2015 as part of a MAGIC monitoring programme are analysed and combined with multi-wavelength data from Fermi-LAT, Chandra, HST, EVN, VLBA and the Liverpool Telescope. The averaged VHE gamma-ray spectrum can be fitted from 100GeV to 10TeV with a simple power law with a photon index of (-2.41 $\pm$ 0.07), while the integral flux above 300GeV is $(1.44 \pm 0.13) \times 10^{-12} cm^{-2} s^{-1}$. During the campaign between 2012 and 2015, M87 is generally found in a low emission state at all observed wavelengths. The VHE gamma-ray flux from the present 2012-2015 M87 campaign is consistent with a constant flux with some hint of variability ($\sim3\sigma$) on a daily timescale in 2013. The low-state gamma-ray emission likely originates from the same region as the flare-state emission. Given the broadband SED, both a leptonic synchrotron self Compton and a hybrid photo-hadronic model reproduce the available data well, even if the latter is preferred. We note, however, that the energy stored in the magnetic field in the leptonic scenario is very low suggesting a matter dominated emission region.