Silicon Photomultiplier Device Research Articles

Performance Characteristics of a New-Generation Digital Bismuth Germanium Oxide PET/CT System, Omni Legend 32, According to NEMA NU 2-2018 Standards.

The Omni Legend 32 PET/CT system features silicon photomultiplier (SiPM)-based detectors with bismuth germanium oxide crystals and a 32-cm axial field of view (FOV). The present study aimed to determine the performance characteristics of the Omni Legend 32 PET/CT system according to National Electrical Manufacturers Association (NEMA) NU 2-2018 standards. Methods: The PET component of this system comprises 22 detector modules; each module contains 24 detector blocks with 72 bismuth germanium oxide crystals with a volume of 4.1 × 4.1 × 30 mm coupled to 18 SiPM devices with a 6 × 6 mm area, resulting in an axial FOV of 32 cm. The spatial resolution, sensitivity, count rate performance, and image quality delivered by PET were evaluated using the NEMA NU 2-2018 standard. PET images of 2 patients were evaluated to get a visual first impression of the Omni Legend 32 PET/CT system together with Precision DL. Results: The average spatial resolution at 1, 10, and 20 cm from the central axis was 4.3, 5.3, and 6.2 mm, respectively, for filtered backprojection and 3.7, 4.3, and 5.1 mm, respectively, for ordered-subset expectation maximization. The NEMA sensitivity was 47.30 and 47.05 cps/kBq at the axial center of the FOV and at a 10-cm radial offset, respectively. The scatter fraction, count rate accuracy, and peak noise-equivalent count rates were 35.4%, 1.7%, and 501.7 kcps, respectively, at 15.7 kBq/mL. Contrast recovery for the NEMA body phantom from the smallest to the largest sphere ranged from 61.3% to 93.0%, with a background variability of 5.4%-11.7% and a lung error of 5.1% for Q.Clear (β-value, 50). Good patient image quality was obtained with the Omni Legend 32. Conclusion: The Omni Legend 32 has class-leading sensitivity and count rates within the category of whole-body PET systems while maintaining spatial resolution broadly comparable to that of other current SiPM-based PET/CT systems. This combination of properties results in a very good image quality.

Achieving significant performance recovery of SiPMs’ irradiation damage with in-situ current annealing

Irradiation damage is one of the main drawbacks restricting the application of Silicon Photomultiplier (SiPM), especially in high irradiance environments such as space, colliders, and nuclear power plants. In-situ current annealing is a method of using the self-current heating of SiPM, and because it does not require disassembly of the SiPM and additional heating devices, it exhibits potential for dealing with radiation damage. We investigate the in-situ annealing performance of three types of SiPM for irradiation damage. The annealing current and time are optimized and the SiPM performance before and after annealing is compared. It was found that after annealing the dark currents of the three types of SiPMs decreased significantly by 1–2 orders of magnitude. Finally, the variation of SiPM performance with temperature is investigated. The energy resolution does not recover as well as the dark current.

High-Density Near-Ultraviolet Silicon Photomultipliers: Characterization of photosensors for Cherenkov light detection

In recent years, Silicon Photomultipliers (SiPMs) have proven to be highly suitable devices for applications where high sensitivity to low-intensity light and fast responses are required. Among their many advantages are their low operational voltage when compared with classical photomultiplier tubes, mechanical robustness, and increased photon detection efficiency (PDE).Here we present a full characterization of a SiPM device technology developed in Italy by Fondazione Bruno Kessler, which is suitable for Cherenkov light detection in the Near-Ultraviolet (NUV) band. This device is a High-Density (HD) NUV SiPM, based on a microcell of 40μm×40μm and with an area of 6 × 6mm2, providing low levels of dark noise and high PDE peaking in the NUV band. This particular device has been selected to equip a part of the focal plane of the Schwarzschild–Couder Telescope (SCT) prototype proposed for the Cherenkov Telescope Array (CTA) Observatory.

Comparison of new SiPM devices for applications in High-Energy physics

Silicon Photo-Multipliers (SiPMs) are widely used as light detectors for the new generation of experiments dedicated to high energy physics. This motivates our goal to tested a number of recent devices from different manufacturers: Hamamatsu 13360-1350; Ketek PM1125; ONsemiconductors FC10035 and AdvanSid NUV4S-P. Particular emphasis has been given to measurements of dark counts and gain, performed at different temperatures by means of a climatic chamber (F.lli Galli model Genviro-030LC) within a temperature range from -60 °C to +60 °C. This allowed evaluating the temperature coefficient of all devices, which was found in agreement with expectations.

Phase 1 upgrade of the CMS Hadron Barrel Calorimeter

The Phase 1 upgrade of the CMS Hadron Calorimeter (HCAL) involved the installation of new silicon photomultiplier devices (SiPMs), which replaced older hybrid photodiodes (HPDs). SiPMs measure the scintillator light output with better signal/noise. The upgraded readout electronics also allow for increased longitudinal segmentation and better performance. This report describes the design, testing, installation, and commissioning of the HCAL Barrel Phase 1 upgrade. Performance results for the HCAL Endcap during Run 2 are presented and expectations for the HCAL Barrel during Run 3 are discussed.

Advanced Back-Illuminated Silicon Photomultipliers With Surrounding P+ Trench

This study conducted the TCAD simulation of an advanced back-illuminated silicon photomultipliers (BI-SiPM) device. This BI-SiPM structure with pixels was surrounded by a p+ trench, which conducted the p+ implant region available on the surface toward the back side. The removal of the metal layer from the incident SiPM surface reduced the blocking of incident light and improved the fill factor of single pixels. Therefore, the photon detection efficiency of BI-SiPM was improved to approximately 70% when the bias voltage was 5 V. The TCAD device simulations were performed to study this BI-SiPM structure, and the quenching process based on Mixedmode emulator was investigated to introduce the BI-SiPM pixel structure into a SPICE circuit. The results indicated that the proposed design could improve the uniform distribution of the electric field and avalanche triggering probability on a photon illuminating surface and increase <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FF</i> , without affecting the crosstalk between pixels. Moreover, the design consideration of manufacturing process flow for BI-SiPM was proposed.

Multiple Use SiPM Integrated Circuit (MUSIC) for Large Area and High Performance Sensors

The 8-channel Multiple Use Silicon Photo-multiplier (SiPM) Integrated Circuit (MUSIC) Application specific integrated circuit (ASIC) for SiPM anode readout has been designed for applications where large photo-detection areas are required. MUSIC offers three main features: (1) Sum of the eight input channels using a differential output driver, (2) eight individual single ended (SE) analog outputs, and (3) eight individual SE binary outputs using a time over threshold technique. Each functionality, summation and individual readout includes a selectable dual-gain configuration. Moreover, the signal sum implements a dual-gain output providing a 15-bit dynamic range. The circuit contains a tunable pole zero cancellation of the SiPM recovery time constant to deal with most of the available SiPM devices in the market. Experimental tests show how MUSIC can linearly sum signals from different SiPMs and distinguish even a few photons. Additionally, it provides a single photon output pulse width at half maximum (FWHM) between 5–10 ns for the analog output and a single-photon time resolution (SPTR) around 118 ps sigma using a Hamamatsu SiPM S13360-3075CS for the binary output. Lastly, the summation mode has a power consumption of ≈200 mW, whereas the individual readout consumes ≈30 mW/ch.

Direct detection of long-duration intense X-ray fluxes with SiPM

In standard applications Silicon Photomultipliers (SiPMs) are usually used for the detection of photons in the infrared to near-ultra violet range or coupled to scintillators to detect higher energy photons or charged perticles. In this work we demonstrate that SiPMs can be used in current mode, measuring the SiPM DC current, to directly detect with high precision long and intense X-ray fluxes in the energy range ∼ 3 ÷ 15 keV . The response factor of the SiPM to X-rays has been determined and the intrinsic saturation current estimated. Furthermore the attenuation length of X-rays in air has been measured exposing the SiPM to a X-ray flux, confirming the validity of the methods. These results indicate that the SiPM device can in principle be calibrated to perform real time measurements in a high intensity X-ray flux environment and that the SiPM DC current is a potential dosimetric variable for online monitoring of X-ray fluxes.

Quantum efficiency of black silicon photodiodes at VUV wavelengths.

Black silicon (b-Si) is an emerging material made by modifying silicon with nanostructures for improved photon detection. It has been demonstrated that when used in photodetectors b-Si significantly improves photon detection and extends spectral sensitivity from NIR to the visible wavelengths. However, no data have been reported in the Vacuum Ultraviolet (VUV) range, which is increasingly becoming important for many applications. Here, we have measured the spectral response of n-type b-Si light-trapping photodiodes under VUV radiation at ambient and cryogenic temperatures. The device exhibited a near-unity quantum efficiency above the 1.1 eV intrinsic bandgap of silicon. Quantum efficiency increased linearly with photon energy above the electron-hole pair creation energy of silicon ∼3.6 eV and the device had a responsivity of 0.2 A/W at 175 nm at room temperature in vacuum. These results demonstrate new technology in UV detection and could pave way for the development of a high quantum efficiency black silicon photomultiplier device (b-SiPM) needed for direct VUV photon detection in noble gas and liquid scintillating detectors.

Electronics method to advance the coincidence time resolution with bismuth germanate

Exploiting the moderate Cherenkov yield from 511 keV photoelectric interactions in bismuth germanate (BGO) scintillators enables one to achieve a level of coincidence time resolution (CTR) appropriate for time-of-flight positron emission tomography (TOF-PET). For this approach, owing to the low number of promptly emitted light photons, single photon time resolution (SPTR) can have a stronger influence on achievable CTR. We have previously shown readout techniques that reduce effective device capacitance of large area silicon photomultipliers (SiPMs) can yield improvements in single photon response shape that minimize the influence of electronic noise on SPTR. With these techniques, sub-100 ps FWHM SPTR can be achieved with mm2 FBK near-ultra-violet high density (NUV-HD) SiPMs. These sensors are also useful for detecting Cherenkov light due to relatively high photon detection efficiency for UV light. In this work, we measured CTR for BGO crystals coupled to FBK NUV-HD SiPMs with a passive bootstrapping readout circuit that effectively reduces the SiPM device capacitance. A range of CTR values between 200 3 and 277 7 ps FWHM were measured for 3 3 3 and 3 3 15 mm3 crystals, respectively. This readout technique provides a relatively simple approach to achieve state-of-the-art CTR performance using BGO crystals for TOF-PET.

Crucial aspects for the use of silicon photomultiplier devices in continuous wave functional near-infrared spectroscopy.

In this work, we investigate some major issues for the use of silicon photomultiplier (SiPM) devices in continuous wave functional near-infrared spectroscopy (CW fNIRS). We analyzed the after-pulsing effect, proposing the physical mechanism causing it, and determining its relevance for CW fNIRS. We studied the SiPM transients occurring as the SiPM device goes from the dark (LED in off state) to the illumination (LED in on state) conditions, and vice-versa. Finally, we studied the SiPM SNR in standard CW fNIRS operation.

Study of silicon photomultiplier performance in external electric fields

We report on the performance of silicon photomultiplier (SiPM) light sensors operating in electric field strength up to 30 kV/cm and at a temperature of 149 K, relative to their performance in the absence of an external electric field. The SiPM devices used in this study show stable gain, photon detection efficiency, and rates of correlated pulses, when exposed to external fields, within the estimated uncertainties. No visible damage to the surface of the devices was caused by the exposure.

Radiation Hardness tests with neutron flux on different Silicon photomultiplier devices

Radiation hardness is an important requirement for solid state readout devices operating in high radiation environments common in particle physics experiments. The MEG II experiment, at PSI, Switzerland, investigates the forbidden decay μ+ → e+ γ. Exploiting the most intense muon beam of the world. A significant flux of non-thermal neutrons (kinetic energy Ek⩾ 0.5 MeV) is present in the experimental hall produced along the beam-line and in the hall itself. We present the effects of neutron fluxes comparable to the MEG II expected doses on several Silicon Photomultiplier (SiPMs). The tested models are: AdvanSiD ASD-NUV3S-P50 (used in MEG II experiment), AdvanSiD ASD-NUV3S-P40, AdvanSiD ASD-RGB3S-P40, Hamamatsu and Excelitas C30742-33-050-X. The neutron source is the thermal Sub-critical Multiplication complex (SM1) moderated with water, located at the University of Pavia (Italy). We report the change of SiPMs most important electric parameters: dark current, dark pulse frequency, gain, direct bias resistance, as a function of the integrated neutron fluency.

Improving the timing accuracy of SiPMs by time‐walk compensation

Timing measurements with silicon photomultipliers (SiPMs) are affected by the major issue of the so-called time-walk effect; this is due to the intrinsic architecture of SiPM devices. A new technique for time-walk compensation in timing measurements with SiPMs is presented and discussed, feasible with a low-complexity and low-cost circuitry and able to improve the timing accuracy. The validity of the presented technique has been experimentally proven with a 3 × 3 mm2 Hamamatsu MPPC, achieving a jitter reduction of a factor 2.85 compared with the case without time-walk compensation. To perform the experimental validation, a discrete-components transimpedance amplifier is developed with large bandwidth and low jitter, specifically designed to read-out and amplify the SiPM signal.

Design and performance of SiPM-based readout of PbF2 crystals for high-rate, precision timing applications

We have developed a custom amplifier board coupled to a large-format 16-channel Hamamatsu silicon photomultiplier device for use as the light sensor for the electromagnetic calorimeters in the Muon g - 2 experiment at Fermilab. The calorimeter absorber is an array of lead-fluoride crystals, which produces short-duration Cherenkov light. The detector sits in the high magnetic field of the muon storage ring. The SiPMs selected, and their accompanying custom electronics, must preserve the short pulse shape, have high quantum efficiency, be non-magnetic, exhibit gain stability under varying rate conditions, and cover a fairly large fraction of the crystal exit surface area. We describe an optimized design that employs the new-generation of thru-silicon via devices. The performance is documented in a series of bench and beam tests.

In-depth study of single photon time resolution for the Philips digital silicon photomultiplier

The digital silicon photomultiplier (SiPM) has been commercialised by Philips as an innovative technology compared to analog silicon photomultiplier devices. The Philips digital SiPM, has a pair of time to digital converters (TDCs) connected to 12800 single photon avalanche diodes (SPADs). Detailed measurements were performed to understand the low photon time response of the Philips digital SiPM. The single photon time resolution (SPTR) of every single SPAD in a pixel consisting of 3200 SPADs was measured and an average value of 85 ps full width at half maximum (FWHM) was observed. Each SPAD sends the signal to the TDC with different signal propagation time, resulting in a so called trigger network skew. This distribution of the trigger network skew for a pixel (3200 SPADs) has been measured and a variation of 50 ps FWHM was extracted. The SPTR of the whole pixel is the combination of SPAD jitter, trigger network skew, and the SPAD non-uniformity. The SPTR of a complete pixel was 103 ps FWHM at 3.3 V above breakdown voltage. Further, the effect of the crosstalk at a low photon level has been studied, with the two photon time resolution degrading if the events are a combination of detected (true) photons and crosstalk events. Finally, the time response to multiple photons was investigated.

A New Simple and Effective Procedure for SiPM Electrical Parameter Extraction

Silicon photomultipliers (SiPMs) are emerging semiconductor-based photosensors, addressing the challenge of low-light detection down to the single-photon counting level. A design of high-performance front-end electronics for SiPM readout requires the development of accurate electrical models. Numerous SiPM reliable models have matured in recent years; however, circuit parameter extraction is rather cumbersome and involves extensive measurement steps to be performed. Starting from a recently developed model of the SiPM device coupled to the conditioning electronics, a new effective analytical procedure is, here, devised for extracting the SiPM model parameters from experimental measurements. The proposed extraction technique is applied to a $3\times 3$ -mm2 SiPM sensor, and is validated by comparing SPICE simulations and measurement results. Independent cross-check validation based on experimental tests corroborates the effectiveness of the adopted extraction procedure.

Scintillation light detection system in LArIAT

The LArIAT experiment is currently taking data at Fermilab using a Liquid Argon TPC, with the aim of studying particle interactions and characterizing detector response for neutrino detectors using argon. In parallel, it serves as a test-bench to develop and evaluate the performance of the simulation, reconstruction, and analysis software used in LAr neutrino experiments. LArIAT also takes advantage of the scintillating capabilities of liquid argon and will evaluate the feasibility of using the light signal to determine calorimetric information and particle identification. To test this possibility, a scintillation light detection system consisting of high Quantum Efficiency (QE) PMT and Silicon Photomultiplier (SiPM) devices is installed in the cryostat, viewing the interior of the TPC. Light collection efficiency is maximized by means of lining the walls with reflector foils covered by a wavelength shifter layer. Collecting the light reflected at the boundaries of the active volume greatly improves also the uniformity of the light yield. Presented here are initial results of the LArIAT light detection system calibration together with the preliminary results of the dedicated simulation and its application in future LAr TPC experiments

Timing resolution performance comparison of different SiPM devices

Silicon photomultiplier (SiPM) devices with improved parameters were recently introduced by several vendors. In addition to published manufacturer performance specifications, different research groups have reported on measurements of the available SiPMs in different operating conditions and using different test setups. In this work we performed a consistent set of test procedures for SiPM devices from various vendors, with focus on Time-of-Flight (TOF) PET detectors applications. SiPMs from Hamamatsu (HPK), SensL, Ketek, and Excelitas were tested. The same experimental setup and procedures were used for comparison of timing resolution for small (3×3mm2) and large (6×6mm2 or 4×6mm2) devices coupled to short (3×3×10mm3) and long (4×4×25mm3) LYSO crystals. The potential opportunities for TOF PET detectors are also evaluated.

Characterization Measurements Methodology and Instrumental Set-Up Optimization for New SiPM Detectors—Part I: Electrical Tests

A comprehensive and in-depth characterization procedure for obtaining very accurate measurements on silicon photomultiplier (SiPM) detectors is described here. A large amount of electro-optical tests are systematically carried out in terms of the most significant SiPM performance parameters; in particular, an accurate estimation of the photon detection efficiency is achieved, based on the single-photon counting technique, with substraction of the dark noise contribution and avoiding the additional noise sources of crosstalk and after pulsing. Some recently produced detectors are analyzed and their relevant electro-optical parameters are evaluated in order to confirm the effectiveness and efficacy of the adopted characterization procedure in assessing the overall SiPM performance. The repeatibility of measurements is carefully verified. All evaluated parameter trends are proved to be compatible with the physics theory of the SiPM device.