Search Results (293)

Silicon photomultipliers (SiPMs) have become widely used as photodetectors in high-energy physics, nuclear physics, medical imaging, and space applications. In many of these fields, SiPMs are required to operate in high-radiation environments, which are notoriously problematic for silicon sensors. For this reason, it is essential to study the changes in their performance characteristics after exposure to radiation. In this study, a number of SiPM samples were exposed to non-uniform radiation at the CHARM facility at CERN. Half of the samples were operated above breakdown during the test, while others remained off. Intermittent measurements allowed for tracking the changes in I-V curves and signal shapes during the irradiation itself. The focus was on detecting differences in irradiation damage between the operational and non-operational SiPM samples. The I-V curves and signal shapes in both cases for three different types of SiPM are presented, and a comparison is made. Full article

The standard first-level trigger in the Pierre Auger Observatory surface detectors (data analysis in FPGAs immediately after digitization in ADCs) was developed when FPGAs were relatively simple and expensive. Thus, the algorithms developed in the 1990s are relatively simple. Substantial progress in electronics now allows the implementation of very sophisticated mathematical algorithms in very efficient systems and relatively inexpensive FPGAs. A neural network was recently developed as an alternative trigger for recognizing neutrino-induced showers, providing relatively high efficiency and allowing signal profiles from Auger photomultiplier tubes of water-Cherenkov detectors originating from atmospheric showers induced by high background neutrinos to be distinguished from other showers. The chemical composition of ultra-high-energy cosmic rays (UHECR) is complex and still not fully known. Additional tools for online, real-time analysis of potential chemical composition could help address this problem. We simulated a large dataset using the CORSIKA package (for simulating the development of extensive air showers in the atmosphere) and OffLine (for generating Cherenkov radiation in surface detectors and digitizing photomultiplier signals in an analog-to-digital converter). These data served as input to a neural network (using MATLAB tools) that attempted to identify the type of initiating particle. Ultimately, the neural network was implemented on an Arria 10 FPGA to generate real-time neural network triggers directly on the pampas in the surface detector. Both simulations and measurements on the Arria 10 development kit confirmed a high degree of reliability. Full article

NanoArduSiPM represents a paradigm shift in the ArduSiPM (Architected Detection Unit for Silicon Photomultipliers) roadmap, evolving from a standalone instrument into a high-density modular building block (36 mm × 42 mm × 3 mm, 7 g). This revision does not merely pursue miniaturization; it re-engineers the signal-processing chain to maintain high performance within a scaled-down footprint, enabling the transition from single-unit detection to scalable, distributed multi-detector systems. NanoArduSiPM is based on a three-layer architecture comprising an external scintillator and Silicon Photomultiplier (SiPM) detection module, a dedicated high-speed discrete analog front-end, and a System-on-Chip (SoC) for embedded acquisition and processing. The physical implementation adopts high-integrity PCB routing and rigorous isolation techniques designed to suppress digital–analog coupling, a critical requirement in such a compact form factor. This deterministic layout strategy provides the architectural foundation for time-tagging capabilities, currently under quantitative characterization, by addressing the fundamental sources of signal interference at the hardware level. Beyond hardware integration, NanoArduSiPM introduces the capability for extended firmware functionality, including event tagging via external inputs and the implementation of coincidence and veto logic. This framework supports the acquisition of multiple correlated histograms and allows multiple units to be interconnected on a shared SPI bus. By shifting from standalone operation to a coordinated, hierarchical architecture, NanoArduSiPM enables distributed detection schemes where event selection and correlation are handled natively within the system, reducing the dependency on external data acquisition electronics. The compact modular architecture, together with the high-performance discrete analog front-end and embedded data handling, makes NanoArduSiPM suitable for applications where low mass and low power consumption are critical, targeting applications such as space-based payloads, laboratory instrumentation, remote sensing, and large-scale distributed multi-channel detection systems. While no radiation-tolerance qualification of the complete system has been performed in this work, the microcontroller family used in the design is also available in radiation-tolerant variants, which may support future implementations targeting more demanding radiation environments. Full article

The aim of this work is to develop high-precision time-of-flight (TOF) devices based on high-refractive-index solid Cherenkov radiators read out by silicon photomultipliers (SiPMs). Cherenkov light is prompt and, therefore, ideal for reaching the intrinsic timing limits of TOF systems. By utilizing a thin, high-refractive-index radiator, a nearly instantaneous signal is generated by particles exceeding the Cherenkov threshold. In order to achieve the ultimate time resolution, we carried out a rigorous optimization of the radiator material and geometry, alongside the efficiency of the optical coupling to the SiPM sensors. The key factors limiting the time resolution were characterized by comprehensive Monte Carlo simulations, subsequently validated against experimental beam test data. We assembled small-scale prototypes instrumented with various Hamamatsu SiPM array sensors with active areas ranging from 1.3 to 3 mm, coupled with various window materials, such as fused silica and MgF₂, featuring various thickness values. The prototypes were successfully tested in beam test campaigns at the CERN-PS T10 beamline. The data were collected with a complete chain of front-end and readout electronics based on either the Petiroc 2A or the Radioroc 2 interfaced to a picoTDC to measure charges and times. By comparing the time measurements from two SiPM arrays, we were able to measure a time resolution better than 33.2 ps at the full system level, with a charged-particle detection efficiency of 100%. Our results demonstrate the expected performance benchmarks for the charged-particle detection efficiency and time resolution, and they highlight the potential of the developed Cherenkov-based TOF detectors for next-generation particle identification systems. Full article

Today, the rapid progress in non-invasive light–matter interaction analysis is transforming the landscape of biomedical and life sciences driven by low-intensity light detection technologies. As the complexity of photonic applications continues to grow, the importance of single-photon detection techniques becomes pivotal. Among them, Time-Correlated Single-Photon Counting (TCSPC) has become the gold standard for precise, time-resolved reconstruction of rapid and faint optical signals. However, TCSPC has long been constrained by pile-up distortion, which worsens with increasing acquisition speed, typically limiting it to 5% of the excitation frequency. To overcome the operational constraints of conventional implementations, a novel TCSPC acquisition methodology has been introduced, independent of photodetector dead time, excitation intensity, and prior optical signal knowledge, still enabling distortion-free reconstruction of the measured light profiles. In this context, the development of single-photon detectors with short dead time and low timing jitter becomes crucial. This work presents a single-photon detection module based on a Silicon Photomultiplier, which delivers 750 ps FWHM output pulses with a 33.5 ps RMS IRF. Its performance is showcased through fluorescence measurements employing the constraint-free TCSPC methodology, achieving a photon count rate up to 166% of the excitation frequency with a minimal lifetime estimation error of just −1.46%. Full article

We present the upgrade and performance evaluation of a silicon photomultiplier (SiPM)-based muon detector, originally designed and developed 15 years ago for radiation tracking applications in radiographic imaging with cosmic muons. The first use of the original assembly and scientific objectives of the detector was in the Mu-Ray project of the Italian National Institute for Nuclear Physics (INFN) for muon radiographic imaging of volcanoes. In addition to its initial uses and after being upgraded with Hamamatsu SiPMs, the detector has been employed in a series of measurement campaigns for the detection of underground cavities. Herein we describe the mechanical recovery process and the integration of modern electronic components aimed at extending the operational capabilities of the detector, with particular attention to the adaptation of the front-end electronics to a new DAQ system. The results of the detector’s characterization and calibration under controlled conditions will be presented, evaluating its current performance and suitability for muography applications in a new geophysical setting. The results confirm that, despite aging, the system remains a viable instrument for precision and reliable muon tracking. Full article

Silicon photomultipliers (SiPMs) are vital for calorimetric applications in high-energy physics and medical imaging due to their high gain, compactness, and insensitivity to magnetic fields. However, their finite pixel count induces non-linear response behaviour at high photon fluxes, affecting energy resolution and systematic accuracy. This work presents a comprehensive methodology to characterise SiPM response functions and derive correction curves using a single-step laser-based measurement approach. Three SiPMs with varying pixel sizes (15, 25 and 50 µm) are studied under controlled temperature conditions, with response functions extracted across different overvoltages and integration windows. The correction method, independent of precise light source calibration, effectively linearises the response up to saturation levels exceeding 100% of the pixel count, achieving deviations of the order of 3% across a broad operational parameter space, and outperforming the traditional calibration model. The analysis demonstrates minimal dependence of the correction on temperature, overvoltage, and pixel size, indicating universal applicability. These findings enhance SiPM performance in high-energy calorimetry and offer a practical framework for improving detector linearity and dynamic range extensions in large-scale applications. Full article

The transverse beam size is a key parameter for characterizing the performance of synchrotron radiation sources. Accurate measurement of the transverse beam size is crucial for assessing beam quality. In this study, a fiber array-photomultiplier tube (PMT) beam measurement system was developed to enable high-precision sampling of beam profile information for beam-size measurement. Furthermore, a hybrid method integrating nonlinear least squares (NLLS) fitting and Gaussian basis-function fitting was proposed to reconstruct the beam intensity profile from discrete sampling data. Before performing NLLS fitting, a median absolute deviation (MAD)-based threshold filter is employed to remove outliers and suppress random noise, thereby improving the stability and robustness of the parameter estimation. The filtered data are then fitted using NLLS to obtain the reconstructed distribution. To capture potential high-order modal features in the beam profile, a Gaussian basis-function fitting model was also introduced for comparison, and its performance was evaluated under complex intensity distributions. Additionally, the relationship between the full width at half maximum (FWHM) and beam intensity was experimentally verified while accounting for measurement effects in the system. The results demonstrate that the proposed hybrid algorithm improves reconstruction accuracy and robustness, enabling precise recovery of the beam-intensity profile in the fiber-array PMT system. Full article

This work presents the development and experimental characterization of a compact ultraviolet (UV) telescope based on silicon photomultipliers (SiPMs) designed for the detection of faint atmospheric optical tracks. Such transient optical phenomena include meteors, transient luminous events (TLEs), space debris reentries, and other faint atmospheric emissions. Nuclearite-induced atmospheric emission is considered as a benchmark case for evaluating the expected signal levels of rare luminous track events. We detail the fabrication, assembly, and testing of the SiPM sensor array, comprising parallel Geiger-mode avalanche diodes with high fill factor and photon detection efficiency, alongside custom readout electronics using self-triggering ASICs, precision optical components, and a stable mechanical mount. This photon-counting telescope provides a compact and mechanically robust alternative to conventional PMT-based systems, with demonstrated capability for detecting low-light atmospheric tracks under controlled laboratory conditions. Full article

A monolithic digital Silicon Photomultiplier (SiPM) featuring 1024 microcells with a 30-micrometer pitch and a 50% fill factor has been designed in a 110-nanometer CMOS image sensor technology. The device under consideration integrates both SPAD sensors and front-end electronics in the same substrate. It can count up to 1024 photons in less than 22 ns, while assigning timestamps to the first and last detected photons with a time resolution of less than 100 ps. A parallel counter structure combined with a fast adder tree provides photon counting in digital form with low latency, whereas a carefully balanced fast NAND tree ensures a fixed-pattern time uncertainty not exceeding 26 ps. The architecture incorporates in-pixel memory for individual cell disabling and configurable thresholding on the timing signal for noise mitigation. In order to optimize the fill factor, a part of the electronics is placed outside the array, while the most sensitive elements of the timing and counting circuits are laid out close to the sensor, in the SPAD array. A serial readout is employed to provide a single output connection per SiPM, thereby simplifying system integration. Full article

The echelle spectrometer utilizes an echelle grating as the primary dispersive element, combined with a prism or planar grating for cross-dispersion, to form a two-dimensional spectral image on an area-array Charge-Coupled Device (CCD). Compared with traditional spectrometers, this configuration provides superior spectral resolution, broader wavelength coverage, enhanced transient direct-reading capability, and higher energy throughput within a similar footprint. However, the use of area-array detectors significantly increases system cost, limiting adoption in cost-sensitive applications. To reduce cost while maintaining performance, we introduce a digital micromirror device (DMD) as a spatial light modulator to replace the traditional area-array detector, paired with a highly sensitive photomultiplier tube (PMT) for signal acquisition. The designed system operates across a wavelength range of 270 to 800 nm within a compact footprint of approximately 307 mm × 210 mm × 150 mm. The focused spot is accurately positioned on the DMD surface across the entire band, with the root mean square (RMS) spot radius smaller than a single micromirror’s size. Spectral information is efficiently coupled into the PMT via a focusing mirror by selectively flipping the DMD micromirrors for detection. Full article

The deployment of Discrete Variable Quantum Key Distribution (DV-QKD) in high-traffic, short-reach environments, such as intra-data center networks, is currently constrained by the saturation of single-photon detectors. While CMOS Single-Photon Avalanche Diodes (SPADs) offer a cost-effective solution, their Secure Key Rate (SKR) is limited by detector dead time. To the best of the authors’ knowledge, this work is the first to derive a generalized detection rate model for SiPMs that addresses the dead-time bottlenecks of gigahertz-rate quantum cryptography. While methods for managing deadtime via active optical switching have been proposed, our model quantifies the benefits of passive spatial multiplexing inherent in standard SiPM arrays. Furthermore, contrasting with models designed to optimize energy resolution or characterize nonlinear charge response to light pulses, our work focuses on maximizing the detection count rate. We derive exact detection rate models for both analog (paralyzable) and digital (non-paralyzable) SiPM architectures, incorporating correlated noise sources such as optical crosstalk and afterpulsing. Simulation results indicate that SiPMs can increase detection rates by over an order of magnitude compared to single SPADs. Full article

The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) is a proposed dual-satellite mission to observe Ultra-High-Energy Cosmic Rays (UHECRs), increase the statistics at the highest energies, and observe Very-High-Energy Neutrinos (VHENs) following multi-messenger alerts of astrophysical transient events, such as gamma-ray bursts and gravitational wave events, throughout the universe. POEMMA–Balloon with radio (PBR) is a small-scale version of the POEMMA design, adapted to be flown as a payload on one of NASA’s suborbital Super Pressure Balloons (SPBs) circling over the Southern Ocean for more than 20 days after a launch from Wanaka, New Zealand. The main science objectives of PBR are: (1) to observe UHECRs via the fluorescence technique from suborbital space; (2) to observe horizontal high-altitude air showers (HAHAs) with energies above the cosmic ray knee (E > 3PeV) using optical and radio detection for the first time; and (3) to follow astrophysical event alerts in the search of VHENs. The PBR instrument consists of a 1.1 m aperture Schmidt telescope similar to the POEMMA design, with two cameras on its focal surface: a Fluorescence Camera (FC) and a Cherenkov Camera (CC). In addition, PBR has a Radio Instrument (RI) optimized for detecting EASs (covering the 60–660 Mhz range). The FC observes UHECR-induced EASs in the ultraviolet (UV) spectrum using an array of 9216-pixel Multi-Anode Photo-Multiplier Tubes (MAPMTs) imaged every 1 $\mathsf{\mu }$s. The CC uses a 2048-pixel Silicon Photo-Multiplier (SiPM) imager to observe cosmic-ray-induced HAHAs and search for neutrino-induced upward-going EASs. The CC covers a spectral range of 320–900 nm, with an integration time of 10 ns. This contribution provides an overview of PBR instruments and their current status. Full article

This work describes the development of the Multi-channel Integrated Zone-sampling Analogue-memory based Readout (MIZAR) ASIC. This 64-channel chip was designed as part of NASA’s POEMMA Balloon with RADIO (PBR) mission, which aims to detect Ultra-High-Energy Cosmic Rays (UHECRs) and $\tau$ showers produced by the interaction of Cosmic Neutrinos (CNs) in the crust. The ASIC was implemented to read out a tile of 8 × 8 Silicon Photomultipliers (SiPMs) used to acquire the optical Cherenkov signals generated by Extensive Air Showers (EASs). A channel is partitioned into 256 cells where each one integrates an analogue memory, a Wilkinson Analog-to-Digital Converter (ADC) and a digital memory operating at the nominal sampling rate of 200 MS/s (with a 5 ns integration time). The signal is digitized on-chip, then the converted data is read out by an FPGA. The MIZAR also provides a 64-bit hitmap as a first-level trigger which can be elaborated by an external firmware. This ASIC can also be configured to further segment the channels into units of 32 or 64 cells each and the ADC resolution can be set to a range between 8 and 12 bits. The chip was designed in a commercial 65 nm CMOS technology node and it was submitted for production in December 2024. The ASICs were delivered in March 2025. Full article

The Advanced Particle–astrophysics Telescope (APT) is a mission concept for a future space-based MeV-TeV observatory, designed to combine a Compton and $e^{+}{e}^{-}$ pair telescope, aiming to improve the sensitivity of the instruments to $\gamma$ rays in the MeV-GeV range by at least one order of magnitude. To validate and study the technologies that will be employed on the observatory, a small-scale prototype, the Antarctic Demonstrator for APT (ADAPT), is currently being developed to fly on a balloon in Antarctica during the local 2026–2027 flight season. Among its subdetectors there is an Imaging CsI calorimeter (ICC), consisting of 4 layers of CsI(Na) crystals with crossed WLS fibers, coupled to Silicon Photomultipliers (SiPMs). A key element of the design is the multichannel front-end electronics, based on the SMART (SiPM Multichannel ASIC for high-Resolution Cherenkov Telescopes) ASIC, which combines compactness, cost-effectiveness, and a high level of integration. This work reports the results of quality-control tests performed on the custom readout boards for the ICC, and provides an overview of the present status of the mission. Full article