Multi-pixel Photon Counter Research Articles

Quantum Calibration of Photon-Number-Resolving Detectors Based on Multi-Pixel Photon Counters

In this paper, we reconstructed the positive operator-valued measure (POVM) of a photon-number-resolving detector (PNRD) based on a multi-pixel photon counter (MPPC) by means of quantum detector tomography (QDT) at 791 nm and 523 nm, respectively. MPPC is a kind of spatial-multiplexing PNRD with a silicon avalanche photodiode (Si-APD) array as the photon receiver. Experimentally, the quantum characteristics of MPPC were calibrated at 2 MHz at two different wavelengths. The POVM elements were given by QDT. The fidelity of the reconstructed POVM elements is higher than 99.96%, which testifies that the QDT is reliable to calibrate MPPC at different wavelengths. With QDT and associated Wigner functions, the quantum properties of MPPC can be calibrated more directly and accurately in contrast with those conventional methods of modeling detectors.

Underwater wireless optical communication based on multi-pixel photon counter and OFDM modulation

A underwater wireless optical communication (UWOC) system using a multi-pixel photon counter (MPPC) as the receiver and orthogonal frequency division multiplexing (OFDM) was proposed and experimentally investigated. The MPPC with high sensitivity combined with quadrature amplitude modulation (QAM) OFDM with high spectral efficiency can potentially support a data rate of hundreds of Mbps under a relatively long underwater transmission distance. Although the photoelectric response of each individual pixel in the MPPC is nonlinear due to its intrinsic dead time, the MPPC consisting of thousands of pixels can be operated like a linear photodetector due to the statistical effect. A net data rate of 312.03 Mbps, with a bit error rate (BER) below the forward error correction (FEC) limit, was successfully achieved over a 21-m underwater channel exploiting 32-QAM OFDM modulation.

Denoising Method for Passive Photon Counting Images Based on Block-Matching 3D Filter and Non-Subsampled Contourlet Transform.

Multi-pixel photon counting detectors can produce images in low-light environments based on passive photon counting technology. However, the resulting images suffer from problems such as low contrast, low brightness, and some unknown noise distribution. To achieve a better visual effect, this paper describes a denoising and enhancement method based on a block-matching 3D filter and a non-subsampled contourlet transform (NSCT). First, the NSCT was applied to the original image and histogram-equalized image to obtain the sub-band low- and high-frequency coefficients. Regional energy and scale correlation rules were used to determine the respective coefficients. Adaptive single-scale retinex enhancement was applied to the low-frequency components to improve the image quality. The high-frequency sub-bands whose line features were best preserved were selected and processed using a symbol function and the Bayes-shrink threshold. After applying the inverse transform, the fused photon counting image was subjected to an improved block-matching 3D filter, significantly reducing the operation time. The final result from the proposed method was superior to those of comparative methods in terms of several objective evaluation indices and exhibited good visual effects and details from the objective impression.

VIDARR: Aboveground Reactor Monitoring

Technology developed for the T2K electromagnetic calorimeter has been adapted to make a small footprint, reliable, segmented detector to characterise anti-neutrinos emitted by nuclear reactors. Based on the design of the T2K Near Detector ECal, the device detects anti-neutrinos through the distinctive delayed coincidence signal of inverse β-decay interactions using plastic scintillator and Hamamatsu Multi-Pixel Photon Counters. The device has been developed and constructed at the University of Liverpool and is situated in a 20 ft ISO container unit, capable of operating aboveground. The device finished a successful field trial at the Wylfa Magnox Reactor on Anglesey, UK where it was located roughly 60 m from the 1.5 GWth reactor core and is now undergoing an upgrade with 50% more mass and channels as well as new electronics and sensors.

Upgraded gamma-ray diagnostics for DT campaigns at JET

For the future JET deuterium-tritium (DT) campaigns numerous gamma-ray diagnostics, in particular the JET Gamma-ray Camera (GC) and the JET Gamma-ray Spectrometer (GS), were upgraded in the last few years. The upgrade of GC and GS included replacement of detector modules in order to allow operation at expected high count rate of ∼0.5 Mcps on the scintillator front surface of 506 mm2 for each GC crystal and 7 squared inches for GS as well as to improve energy resolution to equal or better than 5% at gamma-ray energy above 1.1 MeV for both diagnostics. Within the JET4 Enhancements Project, performance of a number of photodetectors including multi-pixel photon counter (MPPC), PIN diode and photomultiplier tube (PMT) connected to scintillators was investigated. Upgraded detector modules are based on fast scintillators with a decay time of about 20 ns, LaBr3:Ce and CeBr3, coupled to MPPC and PMT for GC and GS, respectively. Results on energy resolution obtained with upgraded diagnostics, already installed at JET, are presented and compared to those collected in laboratory conditions.

Large-area MPPC with enhanced VUV sensitivity for liquid xenon scintillation detector

A large-area Multi-Pixel Photon Counter (MPPC) sensitive to vacuum ultra violet (VUV) light has been developed for the liquid xenon (LXe) scintillation detector of the MEG II experiment. The LXe detector is designed to detect the 52.8MeV photon from the lepton flavour violating decay μ+→e+γ and is based on 900ℓ LXe with a highly granular scintillation readout by 4092 VUV-MPPCs with an active area of 139mm2 each, totalling 0.57m2. The VUV-MPPC shows an excellent performance in LXe, which includes a high photon detection efficiency (PDE) up to 21% for the LXe scintillation light in the VUV range, a high gain, a low probability of the optical cross-talk and the after-pulsing, a low dark count rate and a good single photoelectron resolution. The large active area of the VUV-MPPC is formed by connecting four independent small VUV-MPPC chips in series to avoid the increase of the sensor capacitance and thus, to have a short pulse-decay-time, which is crucial for high rate experiments. Performance tests of 4180 VUV-MPPCs produced for the LXe detector were also carried out at room temperature prior to the installation to the detector and all of them with only a few exceptions were found to work properly. The design and performance of the VUV-MPPC are described in detail as well as the results from the performance tests at room temperature.

SiPM-based dual-ended-readout DOI-TOF PET module based on mean-time method

Positron emission tomography (PET) with high resolution and high sensitivity is desirable for detecting cancers and neurological diseases. In this work, a depth-of-interaction (DOI)-time-of-flight (TOF) PET has been attempted to achieve both high spatial and high timing resolution. Dual-ended readout is a simple technique that can provide excellent timing and DOI resolutions and consistent signal arrival times, regardless of the DOI position along the scintillation crystal, as a mean-time method is used. A dual-ended readout DOI-TOF PET module consisting of a 6 × 6 array of 2 × 2 × 20 mm3 saw-cut cerium-doped lutetium-yttrium oxyorthosilicate (LYSO) crystals is constructed. Both ends of the LYSO crystal array are optically coupled to a multi-pixel photon counter (MPPC) with 4 × 4 channels. The sixteen MPPC outputs are reduced to four position signals using a charge division circuit (CDC) board, and the timing signal is extracted from the common cathode of the MPPC. The four position signals from the MPPC are digitized by a DRS4-based high-speed waveform digitizer with a sampling rate of 5 GSa/s. A 22Na source is placed in front of a reference detector and at the side of the dual-ended readout DOI-TOF PET module in five steps of 2 mm, 6 mm, 10 mm, 14 mm, and 18 mm to measure the DOI, coincidence timing resolutions (CTRs), and mean-times. The full-width-half-maximums (FWHMs) of DOI resolutions and CTRs varied from 3.0 mm to 3.8 mm, with an average of 3.5 mm, and from 333 ps to 367 ps, with an average of 349 ps, respectively. The average of the slopes of the mean-time versus DOI position, for the 36 crystals, was −0.60 ± 1.68 ps/nm, which was consistent with the null value. The dual-ended readout DOI-TOF PET module based on the mean-time method produced both good DOI and CTRs, and consistent signal arrival times. The found solution would be the most advantageous in the small aperture PET systems, such as those for brain and breast imaging.

Single LED-based 46-m underwater wireless optical communication enabled by a multi-pixel photon counter with digital output

Presently, most of the long-reach underwater wireless optical communication (UWOC) systems employ laser diodes rather than light-emitting diodes (LEDs) as the transmitters. Due to lasers’ smaller divergence angles, those UWOC systems could realize longer communication links. Although LED-based long-reach UWOC has distinguished advantages, it suffers from very low received optical power. Fortunately, highly sensitive multi-pixel photon counter (MPPC) and energy efficient pulse position modulation (PPM) pave a way towards LED-based long-reach UWOC. In this paper, we investigated the underlying working principle of an MPPC and proposed a UWOC system based on single LED as well as a lens-free MPPC with digital output. The relationship between the MPPC p.e. threshold and its received optical power was theoretically studied and further proved by experimental results. Single 2.3-MHz, 3-W blue LED was used as the transmitter to generate 8-PPM to 64-PPM signals with a 5-MHz slot frequency. After a 46-m underwater transmission, the measured BERs were all below the forward error correction (FEC) limit, which were achieved with less than 100 incident photons during each pulse slot.

Upgrade of the CsI calorimeter for the KOTO experiment

The aim of the KOTO experiment is to study new physics beyond the standard model via a search for the rare decay . The KOTO detector consists of the electromagnetic calorimeter and hermetic veto counters. To reach the Standard Model sensitivity, we need to reject the neutron-induced backgrounds by a factor of ten. In the summer of 2018, we will start to instrument the front surface of the CsI calorimeter with 4096 multi pixel photon counters (MPPCs) to measure the arrival-time difference between the signals at MPPCs and at photomultiplier tubes connected to the rear surface of the calorimeter. The depth of energy deposition in the shower is measured through the timing difference, which in turn helps to discriminate neutrons and photons. To manage the large number of MPPCs, we have developed an electronics to reduce the number of channels down to 256. The method of gluing between the MPPC and the CsI crystals has been also developed. Using a quartz plate as a medium, the condition of atness is assured in advance and a stable gluing can be performed. By developing a dedicated method to glue the MPPC with the quartz plate, the glue joint gets to be able to endure the decrease of temperature down to -20 °. The functionality of the developed hardwares were con rmed by two beam tests.

Radiation tests of Hamamatsu multi-pixel photon counters

Results of radiation tests of Hamamatsu 2.0 × 2.0 mm2 through-silicon-via (S13360-2050VE) multi-pixel photon counters, or MPPCs, are presented (Hamamatsu, 0000). Distinct sets of eight MPPCs were exposed to four different 1 MeV neutron equivalent doses of 200 MeV protons. Measurements of the breakdown voltage, gain and noise rates at different bias overvoltages, photoelectron thresholds, and LED illumination levels were taken before and after irradiation. No significant deterioration in performance was observed for breakdown voltage, gain, and response. Noise rates increased significantly with irradiation. These studies were undertaken in the context of MPPC requirements for the Cosmic Ray Veto detector of the Mu2e experiment at the Fermi National Accelerator Laboratory.

New DOI Detector Using a Bottom and Side Readouts with a Cross-Arranged Scintillator Array for Positron Emission Tomography

We designed a depth-encoding positron emission tomography (PET) detector by using a bottom and side readout method with a cross-arranged scintillator array. To evaluate the characteristics of the novel detector module, we used the DETECT2000 simulation tool to perform the optical photon transport in the crystal array. The detector module consists of an M (column) × N (row) cross-arranged crystal array composed of M/3 sub-arrays consisting of N × 3 crystals. The second column of the sub-array is arranged perpendicular to the first and the third columns. The crystal is optically coupled to the crystals of the other columns; however, the surfaces between the crystals in the same column are treated as reflectors. A 6 × 5 crystal array consisting of two sub-arrays was considered for proof of concept. The two multi-pixel photon counter (MPPC) arrays are coupled to the bottom and one side of the crystal array, respectively. The x-y position is determined by the bottom MPPC array, and the side MPPC array gives depth information. All pixels in the x-y plane and the z direction were clearly distinguished.

Enhancing the signal-to-noise ratio for laser ranging by adjusting the photon equivalent threshold of a multi-pixel photon counter

A photon equivalent (PE) threshold-adjusting regime for laser ranging is proposed based on a multi-pixel photon counter (MPPC), and the mechanism of PE threshold influence on the signal-to-noise ratio (SNR) is demonstrated and analysed. The unique PE threshold adjustability of an MPPC leads to interesting results for laser ranging. Experimental results show that the SNR of the laser ranging system is significantly improved by optimising the MPPC PE threshold, which is beneficial for detection and false alarm probabilities. Submillimeter laser ranging resolution is obtained with noncooperative targets placed several meters away. Nanosecond dead time single photon laser ranging without gating is obtained due to an MPPC with a small pixel area. Multiple target ranging is implemented with a single MPPC rather than an array.

Evaluation of a novel photon-counting CT system using a 16-channel MPPC array for multicolor 3-D imaging

Abstract X-ray computed tomography (CT) has been widely used in the diagnostic imaging of the interior of the human body. However, the radiation dose of conventional CT typically amounts to 10 mSv. Under such environments, X-ray photons are severely piled-up; therefore, conventional CT acquires energy integrated images, and artifacts are formed by beam hardening. In contrast, a photon counting CT (PC-CT) system is anticipated to construct a low-dose and multi-color CT system. Recently, we proposed a novel PC-CT system using a multipixel photon counter (MPPC) coupled with a high-speed scintillator , which is cost effective and easy to assemble compared to other methods using CdZnTe device. In this paper, we report the results using an advanced CT system consisting of a 16-channel MPPC and scintillator array coupled with a newly developed large-scale integrated circuit (LSI) having an ultrafast signal processing capability. We present the performance of the photon-counting CT capability, such as the contrast of the obtained CT images compared with that of the current-mode CT, and we found that substantial reduction in radiation dose by an order of magnitude. In addition, we report the results of three-dimensional multicolor imaging to identify phantom materials.

High-precision compton imaging of 4.4 MeV prompt gamma-ray toward an on-line monitor for proton therapy

Proton therapy is a widely used and effective treatment for cancer. A high-dose concentration of proton beam reduces damage to normal tissues. However, it also requires a high accuracy of irradiation. PET is generally used to verify the proton range after irradiation, but, the distributions of positrons and the energy deposited by protons are not similar to each other. Recently, prompt gamma-ray imaging has attracted attention as a new, online imaging technique. In particular, 4.4 MeV gamma rays emitted from 12C* is one of the best probes to monitor the proton dose, however imaging techniques are far from established. We have developed a novel, 3-D position sensitive Compton camera based on Ce:GAGG scintillators coupled with multi-pixel photon counter (MPPC) arrays, thus making it optimized for imaging in the 1–10 MeV range. The angular resolution is 5 degrees (FWHM) at 4.4 MeV. We have established various methods to discriminate multiple-Compton and escape events, both of which can be critical backgrounds for precise imaging of prompt gamma rays. By irradiating a 70 MeV proton beam on the PMMA phantom, we demonstrated that 4.4 MeV gamma ray image is sharply concentrated on the Bragg peak, as was expected from the PHITS simulation.

A customized stand-alone photometric Raman sensor applicable in explosive atmospheres: a proof-of-concept study

Abstract. This paper presents an explosion-proof two-channel Raman photometer designed for chemical process monitoring in hazardous explosive atmospheres. Due to its design, alignment of components is simplified and economic in comparison to spectrometer systems. Raman spectrometers have the potential of becoming an increasingly important tool in process analysis technologies as part of molecular-specific concentration monitoring. However, in addition to the required laser power, which restricts use in potentially explosive atmospheres, the financial hurdle is also high. Within the scope of a proof of concept, it is shown that photometric measurements of Raman scattering are possible. The use of highly sensitive detectors allows the required excitation power to be reduced to levels compliant for operation in potentially explosive atmospheres. The addition of an embedded platform enables stable use as a self-sufficient sensor, since it carries out all calculations internally. Multi-pixel photon counters (MPPCs) with large detection areas of 1350 µm2 are implemented as detectors. As a result, the sensitivity of the sensor is strongly increased. This gain in sensitivity is primarily achieved through two characteristics: first, the operating principle “avalanche breakdown” to detect single photons is used; second, the size of the image projected onto the MPPC is much bigger than the pixel area in competing Raman-Spectrometers resulting in higher photon flux. This combination enables reduction of the required excitation power to levels compliant for operation in potentially explosive atmospheres. All presented experiments are performed with strongly attenuated laser power of 35 mW. These include the monitoring of the analytes ethanol and hydrogen peroxide as well as the reversible binding of CO2 to amine. Accordingly, the described embedded sensor is ideally suited as a process analytical technology (PAT) tool for applications in environments with limitations on power input.

Cryogenic electronics for photosensors operating in liquid xenon

Abstract We present the performances and characterization of the cryogenic readout for an array made of Hamamatsu S13370-3050CN (VUV4 generation) Multi-Pixel Photon Counters (MPPC) operated at liquid xenon conditions. The electronics is designed to readout a maximum 64 individual VUV4 photosensors and it is based on the Analog Devices AD8011 current feedback operational amplifier. The AD8011 has been also selected for the realization of a preamplifier embedded onto a voltage divider base for the operation of Hamamatsu R11410 photomultiplier tubes. Results from the radio-purity screening of the AD8011 are also reported.

Towards power-efficient long-reach underwater wireless optical communication using a multi-pixel photon counter.

The transmission distance of underwater wireless optical communication (UWOC) is severely limited by the rapid decay of light intensity in water. Power-efficient pulse position modulation (PPM) and ultra-sensitive multi-pixel photon counter (MPPC) open the door toward designing long-reach UWOC systems. In this paper, a 46-m UWOC system based on PPM and MPPC was proposed and experimentally demonstrated with ultra-low transmitting power into the underwater channel. Clear eye diagrams without any slot error for ten different PPM signals were obtained in the 46-m experiment with data rates of Mbps level. The received optical power was as low as -39.2 dBm for the 10-MHz 4-PPM signal, when the laser worked under the stimulated state. Meanwhile, the received optical power can be reduced to -62.8 dBm, for the 5-MHz 64-PPM signal when the laser worked under the spontaneous state.

Performance study of a large CsI(Tl) scintillator with an MPPC readout for nanosatellites used to localize gamma-ray bursts

We are designing a fleet of nanosatellites to perform accurate position determinations of short-duration gamma-ray bursts by measuring arrival time differences. To achieve sufficient photon statistics to measure the arrival times precisely under the severe limitations of size, mass and power consumption, we propose the use of large-area CsI(Tl) scintillators which provide a high light output and the use of a small-sized multipixel photon counters (MPPC), a kind of SiPM, that have low power consumption. We plan to use one of the latest-model MPPCs provided by Hamamatsu Photonics, namely, S13360-6050CS, which has an active area of 6×6 mm2. We have compared the performance of two scintillators of different sizes (150×75×5 mm3 and 100×75×5 mm3); the bigger one is the maximum size that can be mounted on a three-unit satellite, according to CubeSat standards. We have found that the light yield of the bigger scintillator is lower than that of the smaller one, but the difference is only approximately 13%, and each has an energy threshold of ∼10 keV at 25∘C. We have tested one- and two-MPPC readout and confirmed the same energy thresholds. The light yield for the two-MPPC readout is 1.4 times as high as that for the one-MPPC readout. We have also examined the position dependence of the light yield by using radiation from a 241Am (59.5 keV) source, and confirmed that uniformity was improved, and energy resolution got better by ∼7% for two-MPPC readout.

Study of MPPC damage induced by neutrons

This paper presents the results of neutron irradiation of two types of Multi-Pixel Photon Counter (MPPC). The measurements were taken at the National Centre for Nuclear Research (NCBJ), Poland and the Joint Institute for Nuclear Research (JINR), Russia. Two types of neutron source were used: PuBe with a continuous energy spectrum up to 11 MeV, and mono-energetic 4.8 MeV neutrons produced in a (d,d) reaction. For both sources, fluence in the range of 1010 n/mm2 was achieved. A series of MPPC tests were performed after each irradiation. The changes in MPPC properties, such as current–voltage (I–V) characteristics, breakdown voltage and energy resolution of 662 keV from the 137Cs gamma line for a Gd3Al2.6Ga2.4O12:Ce (1%) scintillator as a function of neutron fluence are presented.

Development of a Portable Muography Detector for Infrastructure Degradation Investigation

A portable muography detector was developed for measuring infrastructure degradation and its performance was tested. The detector consists of two muon position sensitive detectors (mu-PSDs) of the area of 140 mm $\times \,\, 140$ mm, placed in a compact light-shielding box. Each mu-PSD consists of plastic scintillating fibers connected to multipixel photon counters (MPPCs). To suppress the gain deviation of the MPPCs, the box was heat insulated and its inner air temperature was maintained by Peltier cooling–heating modules. The mu-PSD pixel size was 8.75 mm $\times \,\, 8.75$ mm and the distance between the two mu-PSDs was set to 100 mm in order to achieve a solid angle resolution of 8 msr when measuring typical pieces of infrastructure at thicknesses of several tens of centimeters. The intensity of cosmic-ray muons was measured as a function of zenith angle on the ground and was found to be in good agreement with the well-known empirical formula for muon intensity at Earth’s surface. The structural interior of a seven-story concrete building was then successfully imaged with the muography detector placed in the building’s basement.