Characterization and Performance Assessment of a SiPM-Based Muon Detector

A Cosmic Muon Veto (CMV) detector using extruded scintillators is being designed around the mini-Iron Calorimeter detector at the transit campus of the India-based Neutrino Observatory, Madurai for measuring its efficiency at shallow depth underground experiments. The scintillation signal is transmitted through a Wavelength Shifting (WLS) fibre and readout by Hamamatsu Silicon-Photomultipliers (SiPMs). A Light Emitting Diode (LED) system is included on the front-end readout for in-situ calibration of the gain of each SiPM. A characterization system was developed for the measurement of gain and choice of the overvoltage (V ov) of SiPMs using the LED as well as a cosmic muon telescope. The V ov is obtained by studying the noise rate, the gain of the SiPM, and the muon detection efficiency. In case of any malfunction of the LED system during the operation, the SiPM can also be calibrated with the noise data as well as using radioactive sources. This paper describes the basic characteristics of the SiPM and the comparison of the calibration results using all three methods, as well as the V ov of the SiPMs and muon selection criteria for the veto detector.

Renewable energy dependence on variable weather creates mismatches with energy demand. One possible solution is to produce and store green hydrogen by energy surpluses for later use. While surface storage options are limited, subsurface storage in salt caverns (200 m to 2 km deep) is more suitable due to their favorable properties. However, imaging these caverns is difficult because traditional geophysical methods often lack the resolution or depth penetration needed, making it challenging to study such formations effectively. Many of the limitations of conventional geophysical prospecting methods can be addressed by Muon Radiography (MR), an advanced technique that uses cosmic muons to detect underground density variations. Because muons penetrate deeply, their attenuation reveals information about the density and structure of the material, allowing for the identification of cavities with high spatial resolution over several hundred meters. This article presents a MR project aimed at imaging and characterizing underground salt caverns in southern Sicily. A muon detector was first installed at the surface to collect a calibration sample of free-sky muons, then moved to an underground gallery at -106 m ASL to test the method near a known tunnel. The paper includes expected results from synthetic data and first data analysis from the calibration and underground samples.

Renewable energy dependence on variable weather creates mismatches with energy demand. One possible solution is to produce and store green hydrogen by energy surpluses for later use. While surface storage options are limited, subsurface storage in salt caverns (200 m to 2 km deep) is more suitable due to their favorable properties. However, imaging these caverns is difficult because traditional geophysical methods often lack the resolution or depth penetration needed, making it challenging to study such formations effectively. Many of the limitations of conventional geophysical prospecting methods can be addressed by Muon Radiography (MR), an advanced technique that uses cosmic muons to detect underground density variations. Because muons penetrate deeply, their attenuation reveals information about the density and structure of the material, allowing for the identification of cavities with high spatial resolution over several hundred meters. This article presents a MR project aimed at imaging and characterizing underground salt caverns in southern Sicily. A muon detector was first installed at the surface to collect a calibration sample of free-sky muons, then moved to an underground gallery at -106 m ASL to test the method near a known tunnel. The paper includes expected results from synthetic data and first data analysis from the calibration sample.

Development of a muon detector based on a plastic scintillator and WLS fibers to be used for muon tomography system

The design of combined positron emission tomography/magnetic resonance (PET/MR) systems presents a number of challenges to engineers, as it forces the PET system to acquire data in a space constrained environment that is sensitive to electro-magnetic interference and contains high static, radio frequency and gradient fields. In this work we validate fast timing performance of a PET scintillation detector using a potentially very compact, very low power, and MR compatible readout method in which analog silicon photomultipliers (SiPM) signals are transmitted optically away from the MR bore with little or even no additional readout electronics. This analog ‘electro-optial’ method could reduce the entire PET readout in the MR bore to two compact, low power components (SiPMs and lasers). Our experiments show fast timing performance from analog electro-optical readout with and without pre-amplification. With 3 mm × 3 mm × 20 mm lutetium–yttrium oxyorthosilicate (LYSO) crystals and Excelitas SiPMs the best two-sided fwhm coincident timing resolution achieved was 220 +/− 3 ps in electrical mode, 230 +/− 2 ps in electro-optical with preamp mode, and 253 +/− 2 ps in electro-optical without preamp mode. Timing measurements were also performed with Hamamatsu SiPMs and 3 mm × 3 mm × 5 mm crystals. In the future the timing degradation seen can be further reduced with lower laser noise or improvements SiPM rise time or gain.

Time resolution of time-of-flight detector based on multiple scintillation counters readout by SiPMs

Silicon photomultiplier properties at cryogenic temperatures

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 is an 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%Ca crystals of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 2\times $ </tex-math></inline-formula> 3 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and LYSO:Ce:0.2%Ca of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.13\times 3.13\times $ </tex-math></inline-formula> 20 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup>, we measured a coincidence time resolution (CTR) of (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$95~\pm ~3$ </tex-math></inline-formula>) and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$156~\pm ~4$ </tex-math></inline-formula>) ps full width half maximum (FWHM), respectively. With Fondazione Bruno Kessler NUV-HD LF2 M0 SiPMs coupled to the same crystals, we obtained a CTR of (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$76~\pm ~2$ </tex-math></inline-formula>) and (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$127~\pm ~3$ </tex-math></inline-formula>) 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.

Muon imaging technology has developed rapidly over the past decades with extensive applications. In many cases, plastic scintillator detectors are preferred because of their high cost performance, ease of processing and robustness in harsh environments. To reduce imaging time and improve imaging quality, detectors tend to have large areas and high position resolutions. The challenge to the electronics for such detectors is to maintain the scale of electronics acceptable while improving the high position resolution of the detector. In this paper, the basic detector unit is a triangular strip of plastic scintillator, each embedded with two wavelength-shifting (WLS) fibers read out by the silicon photomultipliers (SiPMs). Since the hit position of muon on the detector is determined by the splitting ratio of the scintillation light on two adjacent scintillator strips, it is necessary the readout electronics has high linearity and low noise. The possibility of the electronics channel multiplexing on the same detector plane is fully explored so that four WLS fibers can be read out by one SiPM realizing 2:1 readout channel compression. Furthermore, since multiple electronics modules are connected by a daisy chain structure, the electronics system is very scalable with its data acquisition system (DAQ) independent of detector size. In addition to detailing the position encoding readout scheme, the design of electronics module and the DAQ system, the electronics system has been implemented and applied to a prototype detector for performance evaluation. Using scintillator strips with 11 mm pitch size, the position resolution of the detector reaches 1.49 mm, which demonstrates that the designed electronics is suitable for the new detector structure, and the combination of the two has a good application prospect in muon imaging.

Influence of X-ray irradiation on the properties of the Hamamatsu silicon photomultiplier S10362-11-050C

We have investigated the effects of X-ray radiation of doses of 0, 200 Gy, and 20 kGy on the Hamamatsu silicon-photomultiplier (SiPM) S10362-11-050P. From current-voltage, capacitance/conductance-voltage, pulse-shape and pulse-height measurements, the SiPM characteristics below and above breakdown voltage were determined. Significant changes are observed, however, the changes above the breakdown voltage hardly affect the operation of SiPMs. We conclude that the operation of the Hamamatsu SiPM as high-gain photodetector is hardly affected by X-ray radiation damage in the dose range investigated.

Cosmic muons are highly energetic and penetrative particles and these figures are used for imaging of large and dense objects such as spent nuclear fuels in casks and special nuclear materials in cargo. Cosmic muon intensity depends on the incident angle (zenith angle, φ), and it is known that I(φ) = I0 cos2 φ at sea level. Low intensity of cosmic muon requires long measurement time to acquire statistically meaningful counts. Therefore, high-energy particle simulations e.g., GEANT4, are often used to guide measurement studies. However, the measurable cosmic muon count rate changes upon detector geometry and configuration. Here we develop an “effective solid angle” model to estimate experimental results more accurately than the simple cosine-squared model. We show that the cosine-squared model has large error at high zenith angles (φ ≥ 60°), whereas our model provides improved estimations at all zenith angles. We anticipate our model will enhance the ability to estimate actual measurable cosmic muon count rates in muon imaging applications by reducing the gap between simulation and measurement results. This will increase the value of modeling results and improve the quality of experiments and applications in muon detection and imaging.

Cosmic ray muon tomography is a promising method for the non-invasive inspection of shipping containers and trucks. It leverages the highly penetrating cosmic muons and their interactions with various materials to generate three-dimensional images of large and dense objects, such as inter-modal shipping containers, which are typically opaque to conventional X-ray radiography techniques. One of the key tasks of customs and border security is verifying shipping container declarations to prevent illegal trafficking, and muon tomography offers a viable solution for this purpose. Common imaging methods using muons rely on data analysis of either muon scattering or absorption–transmission. We design a compact muon tomography system with dimensions of 3 × 3 × 3 m3, consisting of 2D position-sensitive detectors. These detectors include plastic scintillators, wavelength-shifting (WLS) fibers, and SiPMs. Through light transport modeling with GEANT4, we demonstrate that the proposed detector design—featuring 1 m × 1 m scintillator plates with 2 mm2 square-shaped WLS fibers—can achieve a spatial resolution of approximately 0.7–1.0 mm. Through Monte Carlo simulations, we demonstrate that combining muon scattering and absorption data enables the rapid and accurate identification of cargo materials. In a smuggling scenario where tobacco is falsely declared as paper towel rolls, this combined analysis distinguishes the two with 3 σ confidence at a spatial resolution of 1 mm (FWHM) for the muon detector, achieving results within a scanning time of 40 s for a 20-foot shipping container.

The gain of silicon photomultipliers (SiPMs) increases with bias voltage and decreases with temperature. To operate SiPMs at stable gain, the bias voltage can be readjusted to compensate for temperature changes. We have tested this concept with 30 SiPMs from three manufacturers (Hamamatsu, KETEK and CPTA) operating in a climate chamber at CERN by varying temperatures between 1̂ C and 48̂ C. We built an adaptive power supply that uses a linear dependence of the bias voltage on temperature. We stabilized four SiPMs simultaneously with only one compensation parameter for the readjustment of the bias voltage of four SiPMs. For all tested Hamamatsu and CPTA SiPMs we achieved our goal of limiting gain changes to less than ± 0.5% in the 20–30̂C temperature range.

This report presents a concept of constructing a detector dedicated for detection of muons observed during measurements carried out at the MPD (Multi-Purpose Detector) detector that is currently under construction at the NICA facility, Russia, Dubna. It has been proposed to design and build an additional detector that will complement the current MPD set and increase its measurement capabilities. The main goal of this project is to provide information from cosmic muons that pass the MPD detector in both in-beam and off-beam experiments. Hence, the detector is called the MPD COsmic Ray Detector (MCORD).The conceptual design of MCORD is proposed by a Polish consortium NICA-PL comprising several Polish scientific institutions.The data from cosmic ray muons could be used as a trigger for calibration of other detection systems comprising the MPD detector. Large surface covered by the MCORD offers also possibility for efficient registration of muons generated in expanding atmospheric showers induced by distant sources. Moreover, beyond some energy threshold, observation of muons originating from decays of collision products will also be possible. In this report examples of the MCORD functionality as a part of the MPD detector are presented.The MCORD is designed as a universal, fast triggering system built as a modular reconfigurable construction. The detection system will be based on plastic scintillators equipped with wavelength shifting fibers, and silicon photomultipliers (SiPM) will be used for scintillation readout. The online analysis of received signals will be performed using digital FPGA modules. Due to the modular design, the same system (its small part) can be used for both laboratory testing of other MPD sub-detectors, and the calibration of these detectors after placing them inside the MPD in off-beam mode. The full detector will support these systems as an additional trigger, calibrator, and muon identifier during the normal operation of the MPD detector with the beam. Thanks to its unique construction, it will expand the possibilities of collecting scientific data of the MPD detector with astrophysical observations.The publication will show the assumptions of the mechanical structure and electronic systems of the planned detector. The installation site of the detector as part of the MPD detector will be described in detail. In the following, the results of simulations made in preparation for this project will be presented. In particular, simulations with the CORSIKA code present angular distributions of particles in cosmic showers in the Dubna city region. Since muons dominate the cosmic ray showers, the MPD detector response to expected cosmic muon flux was also simulated. The results provide information about the muon cut-off thresholds depending on the MPD detector composition during the installation campaign. Simulations of muon events that could be used for MPD subsystems calibration were also performed. The results shown for various configuration of MCORD detector modules will enable the estimation of the time necessary to perform such tests in the future.Simulations with UrQMD model shows the muon abundances due to beam-beam collisions. Approximately 90% of muons are created from pions, whereas the number of muons that reach the MCORD detector is 10 times greater than the number of pions. The MPD detector response was also simulated under the influence of a stream of various particles, especially muons. It shows energy dependence of muon transmission coefficient for MPD with and without ECal assembled. Assuming requirement for muon transmission above 95%, the muon cut-off thresholds are 1.6 GeV and 2.0 GeV, respectively.MCORD detector performance evaluation is also reported. In the case when we used scintillators with one fiber with a diameter of 1 mm, the time resolution of about 1.0 ns was recorded, which corresponds to the positional accuracy (σx) of 7.1 cm. The results of laboratory tests show that application of a 2 mm diameter WLS fiber instead of the previously used 1 mm diameter fiber improves the time resolution to 0.80 ns.