Photomultiplier Tube Research Articles

Near-unity excess noise factor of staircase avalanche photodiodes

If a receiver system is circuit-noise limited, avalanche photodiodes can be beneficial, as their internal gain mechanism can lead to a higher system signal-to-noise ratio. However, the extent of this benefit is intrinsically limited by the detectors’ excess noise factor. The higher the factor, the lower the overall signal-to-noise ratio. The staircase avalanche photodiode proposed by Federico Capasso was designed to be a solid-state replacement for a photomultiplier tube in which discrete and deterministic gain would lead to a unity excess noise factor. The predicted gains for a staircase avalanche photodiode have recently been confirmed for one-, two-, and three-step structures [Nat. Photonics 15, 468 (2021)NPAHBY1749-488510.1038/s41566-021-00814-x]. This paper presents measurements of the excess noise factor of two- and three-step staircase avalanche photodiodes. At an average gain of 4.01 and 7.24, the two- and three-step staircase avalanche photodiodes have an average excess noise factor of 1.02 and 1.08, respectively.

Studying bioluminescence flashes with the ANTARES deep‐sea neutrino telescope

AbstractWe develop a novel technique to exploit the extensive data sets provided by underwater neutrino telescopes to gain information on bioluminescence in the deep sea. The passive nature of the telescopes gives us the unique opportunity to infer information on bioluminescent organisms without actively interfering with them. We propose a statistical method that allows us to reconstruct the light emission of individual organisms, as well as their location and movement. A mathematical model is built to describe the measurement process of underwater neutrino telescopes and the signal generation of the biological organisms. The Metric Gaussian Variational Inference algorithm is used to reconstruct the model parameters using photon counts recorded by photomultiplier tubes. We apply this method to synthetic data sets and data collected by the ANTARES neutrino telescope. The telescope is located 40 km off the French coast and fixed to the sea floor at a depth of 2475 m. The runs with synthetic data reveal that we can model the emitted bioluminescent flashes of the organisms. Furthermore, we find that the spatial resolution of the localization of light sources highly depends on the configuration of the telescope. Precise measurements of the efficiencies of the detectors and the attenuation length of the water are crucial to reconstruct the light emission. Finally, the application to ANTARES data reveals the first localizations of bioluminescent organisms using neutrino telescope data.

An Exposure Meter of Lijiang Fiber-fed High-Resolution Spectrograph

In 2016, an exposure meter was installed on the Lijiang Fiber-fed High-Resolution Spectrograph to monitor the coupling of starlight to the science fiber during observations. Based on it, we investigated a method to estimate the exposure flux of the CCD in real time by using the counts of the photomultiplier tubes (PMT) of the exposure meter, and developed a piece of software to optimize the control of the exposure time. First, by using flat-field lamp observations, we determined that there is a linear and proportional relationship between the total counts of the PMT and the exposure flux of the CCD. Second, using historical observations of different spectral types, the corresponding relational conversion factors were determined and obtained separately. Third, the method was validated using actual observation data, which showed that all values of the coefficient of determination were greater than 0.92. Finally, software was developed to display the counts of the PMT and the estimated exposure flux of the CCD in real-time during the observation, providing a visual reference for optimizing the exposure time control.

Magnetic shielding simulation for particle detection

Cherenkov-type particle detectors or scintillators use as a fundamental element photomultiplier tubes, whose efficiency decreases when subjected to the Earth’s magnetic field. This work develops a geomagnetic field compensation system based on coils for large scale cylindrical detectors. The effect of different parameters such as the size of the detector, the distance between coils or the magnetic field strength on the compensation using a basic coil system composed of circular and rectangular coils is studied. The addition of coils of very specific geometry and position to the basic configuration is proposed in order to address the compensation in the areas of the detector where it is more difficult to influence, in order to minimize the loss of efficiency. With such improvement, in the considered simulated system, more than 99.5% of the photomultiplier tubes in the detector experience an efficiency loss of less than 1% due to the effect of the magnetic fields.

Photomultiplier tube signal conditioning for high-temperature applications

Abstract Ionizing radiation detection in harsh environment conditions often requires additional signal processing to match the requirements of the commercial data readout systems. The subject of this paper is the design of the high-temperature (HT) signal conditioning module that ensures the applicability of scintillation detectors that utilize photomultiplier tubes (PMT) with moderate sampling rate instrumentation. The design was developed for the operation in HT environments (up to 120°C). In order to achieve the optimal signal shape, the module combines a charge amplifier and a low-pass filtering circuitry. An embedded power supply section makes it a complete, standalone unit requiring a single 12 V supplying line. A comprehensive analysis of the developed device, named “PreAmp Shape”, was conducted in order to prove the intended functionality over the different working conditions.

Fast-sampling fast-ion D-alpha measurement using multi-anode photomultiplier tube in large helical device.

A fast-sampling fast-ion D-alpha (F-FIDA) measurement has been developed in the large helical device in order to investigate fast ion dynamics associated with helically trapped fast-ion-driven Magnetohydrodynamic (MHD) bursts. F-FIDA consists of a multi-anode photomultiplier tube (PMT) and achieves a sampling rate of 10kHz. During the deuterium experiment campaign in 2022, F-FIDA measured the spectrum of perpendicular fast ions, using perpendicular lines of sight. We compared F-FIDA with conventional FIDA, using an electron multiplying charge coupled device, and confirmed that the time-averaged images were generally consistent between the two. The statistical properties of the temporal evolution associated with MHD bursts were analyzed using a conditional sampling technique. The results showed that the PMT signal varied in different spatial and wavelength channels. Although the signal-to-noise ratio was poor and there was room for improvement, it could provide useful information for studies on the phase-space dynamics of fast ions.

CALIBRATION OF 122 SENSL MICROFJ-60035 SIPMS AND THE REDUCTION OF OPTICAL CROSS-TALK DUE TO COUPLED LIGHT GUIDES

Recent silicon photomultipliers (SiPMs) boast excellent production quality, eliminating the need for individual breakdown voltage calibration. We present measurements of cross-talk probability and relative gain for 122 SensL MicroFJ-60035-TSV SiPMs. These semiconductor photosensors have replaced photomultiplier tubes in many applications due to their single-photon resolution, insensitivity to magnetic fields, robustness, and cost-effective photon detection at lower voltages. Light guides expand SiPMs' small photosensitive area, and optical coupling reduces cross-talk probability compared to bare sensors at nominal bias voltage, as demonstrated in this study.

RAAD: LIGHT-1 CubeSat's payload for the detection of terrestrial gamma-ray flashes

The Rapid Acquisition Atmospheric Detector (RAAD), onboard the LIGHT-1 3U CubeSat, detects photons between hard X-rays and soft gamma-rays, in order to identify and characterize Terrestrial Gamma Ray Flashes (TGFs). Three detector configurations are tested, making use of Cerium Bromide and Lanthanum BromoChloride scintillating crystals coupled to photomultiplier tubes or Multi-Pixel Photon Counters, in order to identify the optimal combination for TGF detection. High timing resolution, a short trigger window, and the short decay time of its electronics allow RAAD to perform accurate measurements of prompt, transient events. Here, we describe the overview of the detection concept, the development of the front-end acquisition electronics, as well as the ground testing and simulation that the payload underwent prior to its launch on December 21st, 2021. We further present an analysis of the detector's in-orbit system behavior and some preliminary results.

Development of the digital multichannel analyzer for liquid scintillation detection

The new digital multichannel analyzer (DMCA) based on field programmable gate array (FPGA) technology is successfully developed, and it is used for liquid scintillation detection. The performance of this system has been evaluated. The analog signal output emanating from the photomultiplier tube (PMT) is transformed into digital signals through the utilization of an amplifier and a high-speed analog-to-digital converter (ADC). Information about the energy, timing, and pulse shape characteristics of the radiation event is contained in the digital signal. Subsequently, this digital signal is directed towards the FPGA for digital signal processing. In order to reduce the thermal and electronic noise, the dual-channels configuration and the signal coincidence function are added to DMCA for optimizing the validity of signal. The signal coincidence unit is designed within the FPGA, optimizing the synchronization of signals. The measurement data is transmitted to a computer via USB interface. The energy spectra of gamma sources, namely 22Na, 60Co, and 137Cs, as well as the alpha source 232Th, were measured utilizing the newly developed system. Notably, thermal and electronic noise interference is reduced in the coincidence measurement mode, and the coincidence energy spectra are improved compared to the singles measurement. In contrast to commercially available systems, the advantages of our design in terms of miniaturization, cost-effectiveness, and expandability are demonstrated.

A study on performance boost of a 17 m class Cherenkov telescope with a SiPM-based camera

The current generation of Imaging Atmospheric Cherenkov Telescopes (IACTs), comprised of major installations such as the MAGIC, H.E.S.S. and VERITAS telescopes, is sometimes called the 3rd generation of such instruments. These telescopes use multipixel cameras composed of hundreds up to thousands photomultiplier tubes (PMTs). The supremacy of PMTs is currently being challenged by photon sensors, rapidly spreading in popularity: the silicon photomultipliers (SiPMs), that are becoming a valid alternative thanks to their high PDE, low operating voltage and flexibility in installation. In this report, we investigate the performance of an existing 3rd generation IACT array (taking as a working example MAGIC), in which PMTs would be replaced with SiPMs, applying generalized simulations, not tuned for a specific hardware solution. We find an energy-dependent improvement in sensitivity, reaching a factor of three at the current trigger threshold energy. Interestingly, we also find that the stronger sensitivity of SiPMs in the red part of the spectrum, a source of background for IACTs, does not affect this performance.

A scintillation dosimeter with real-time positional tracking information for in vivo dosimetry error detection in HDR brachytherapy.

To evaluate the performance of an electromagnetic (EM)-tracked scintillation dosimeter in detecting source positional errors of IVD in HDR brachytherapy treatment. Two different scintillator dosimeter prototypes were coupled to 5 degrees-of-freedom (DOF) EM sensors read by an Aurora V3 system. The scintillators used were a 0.3 × 0.4 × 0.4 mm3 ZnSe:O and a BCF-60 plastic scintillator of 0.5 mm diameter and 2.0 mm in length (Saint-Gobain Crystals). The sensors were placed at the dosimeter's tip at 20.0 mm from the scintillator. The EM sampling rate was 40/s while the scintillator signal was sampled at 100 000/s using two photomultiplier tubes from Hamamatsu (series H10722) connected to a data acquisition board. A high-pass filter and a low-pass filter were used to separate the light signal into two different channels. All measurements were performed with an afterloader unit (Flexitron-Elekta AB, Sweden) in full-scattered (TG43) conditions. EM tracking was further used to provide distance/angle-dependent energy correction for the ZnSe:O inorganic scintillator. For the error detection part, lateral shifts of 0.5 to 3 mm were induced by moving the source away from its planned position. Indexer length (longitudinal) errors between 0.5 to 10 mm were also introduced. The measured dose rate difference was converted to a shift distance, with and without using the positional information from the EMsensor. The inorganic scintillator had both a signal-to-noise-ratio (SNR) and signal-to-background-ratio (SBR) close to 70 times higher than those of the plastic scintillator. The mean absolute difference from the dose measurement to the dose calculated with TG-43U1 was 1.5% ±0.7%. The mean absolute error for BCF-60 detector was 1.7% when compared to TG-43 calculations formalism. With the inorganic scintillator and EM tracking, a maximum area under the curve (AUC) gain of 24.0% was obtained for a 0.5-mm lateral shift when using the EMT data with the ZnSe:O. Lower AUC gains were obtained for a 3-mm lateral shifts with both scintillators. For the plastic scintillator, the highest gain from using EM tracking information occurred for a 0.5-mm lateral shift at 20 mm from the source. The maximal gain (17.4%) for longitudinal errors was found at the smallest shifts (0.5 mm). This work demonstrates that integrating EM tracking to in vivo scintillation dosimeters enables the detection of smaller shifts, by decreasing the dosimeter positioning uncertainty. It also serves to perform position-dependent energy correction for the inorganic scintillator,providing better SNR and SBR, allowing detection of errors at greater distances from thesource.

The JUNO experiment Top Tracker

The main task of the Top Tracker detector of the neutrino reactor experiment Jiangmen Underground Neutrino Observatory (JUNO) is to reconstruct and extrapolate atmospheric muon tracks down to the central detector. This muon tracker will help to evaluate the contribution of the cosmogenic background to the signal. The Top Tracker is located above JUNO’s water Cherenkov Detector and Central Detector, covering about 60% of the surface above them. The JUNO Top Tracker is constituted by the decommissioned OPERA experiment Target Tracker modules. The technology used consists in walls of two planes of plastic scintillator strips, one per transverse direction. Wavelength shifting fibres collect the light signal emitted by the scintillator strips and guide it to both ends where it is read by multianode photomultiplier tubes. Compared to the OPERA Target Tracker, the JUNO Top Tracker uses new electronics able to cope with the high rate produced by the high rock radioactivity compared to the one in Gran Sasso underground laboratory. This paper will present the new electronics and mechanical structure developed for the Top Tracker of JUNO along with its expected performance based on the current detector simulation.

Performance of Wide Dynamic Photomultiplier Applied in a Low Blind Zone Lidar

Aerosol lidars play a vital role in the investigations of atmospheric pollution formation and meteorological processes. The intensity of lidar return signals in the near range changes much faster compared with the one in the far range, so extremely wide dynamic outputs from the photomultiplier tube (PMT) are needed to avoid saturation in the near range. Usually, to obtain the wide dynamic range, simultaneously, a transient digitizer (Licel) is applied to provide an analog detection chain for strong signals and a photon counting (PC) detection chain for weak signals. However, the near-range signals are still often saturated due to the very high aerosol loading. In this paper, we proposed to use a new PMT module with eight orders of magnitude for a low blind zone lidar, which can achieve both analog and PC separately. A comprehensive evaluation of this potential PMT, which could perform better in near-range detection, compared with the ordinary PMT was tested, but similar features are maintained in the far-range. The photon count rate and signal-to-noise ratio were tested for both the new PMT module and the ordinary PMT module. The results showed that the new PMT module is useful to extend the dynamic range of lidar detection.

Energy resolution, peak to total ratio, peak to Compton ratio of cerium bromide crystal scintillator

Background: CeBr3 Inorganic scintillator is a favorite scintillator in various fields, especially in medical imaging and X-rays/gamma rays detectors. One is important before being applied in any application is the fundamental properties that it has to measure such as energy resolution, PTR, PCR, and light yield. Objectives: In this research, a CeBr3 crystal was carried out trial for calculating the energy resolution, peak to total (PTR), and peak to Compton (PCR) values. Materials and methods: When high photon energy undergoes with the CeBr3 crystal, the crystal will occur to interact with photon energy by energy’s absorptions via the interaction ternary as the photoelectric absorption, Compton scattering, and pair production. The nuclear instrument module (NIM) was used in this experiment. The crystal will generate light and come into a photomultiplier tube (PMT 9256 KB) for amplifying the light signal via the radiation sources as Ba-133, Na-22, Cs-137, and Co-60, which generated the energies at 0.356 MeV, 0.511 MeV, 0.662 MeV, 1.173 MeV, and 1.332 MeV, respectively. Results: The result found that the energy resolution of CeBr3 showed the energy resolution of CeBr3 crystal showed a linear pattern of inverse the square root of the energy and found the energy resolution values were increased when the photon energy decreased. The PTR and PCR values decreased with increasing energy ranges via experiment of each full energy peak of radiation sources. Conclusion: From the fundamental properties of CeBr3 crystal showed a good energy resolution and is a possible candidate to apply for any application such as radiation detection and high-energy physics. Anywise, other properties should be also considered, for example, light yield, decay time, and nonproportionality of light yield.

Lightwave‐Driven Long‐Wavelength Photomultipliers

AbstractA novel lightwave‐driven detector that combines photomultiplier tube (PMT) technology with structured metasurfaces is presented to enable efficient detection of long‐wavelength radiation in the mid‐infrared (mid‐IR) to terahertz (THz) range. This overcomes the limitations of conventional PMT technology, which cannot efficiently detect wavelengths longer than 1.7 m. The approach utilizes the long‐wavelength radiation's instantaneous electric field to facilitate field‐driven electron emission from metasurfaces, which allows it to cover the entire THz to mid‐IR range by geometric scaling. This enables a novel class of lightwave‐driven detectors with the benefits and performance characteristics known from the established PMT technology, such as fast response times and low noise, while expanding the operational wavelength range vastly. It is shown that the amount of field‐emitted electrons depends on the THz electric field in a highly nonlinear manner, generally following the Fowler–Nordheim relation. Furthermore, the THz‐PMT can determine specific lightwave characteristics of the incident field, including its peak field strength and absolute polarity, due to its sensitivity to the sign of the electric field. With a field sensitivity as low as a few kV cm−1, the THz‐PMTs provide a versatile tool for high sensitivity detection across various fields of interest in science and technology.

Optimal sparsity allows reliable system-aware restoration of fluorescence microscopy images.

Fluorescence microscopy is one of the most indispensable and informative driving forces for biological research, but the extent of observable biological phenomena is essentially determined by the content and quality of the acquired images. To address the different noise sources that can degrade these images, we introduce an algorithm for multiscale image restoration through optimally sparse representation (MIRO). MIRO is a deterministic framework that models the acquisition process and uses pixelwise noise correction to improve image quality. Our study demonstrates that this approach yields a remarkable restoration of the fluorescence signal for a wide range of microscopy systems, regardless of the detector used (e.g., electron-multiplying charge-coupled device, scientific complementary metal-oxide semiconductor, or photomultiplier tube). MIRO improves current imaging capabilities, enabling fast, low-light optical microscopy, accurate image analysis, and robust machine intelligence when integrated with deep neural networks. This expands the range of biological knowledge that can be obtained from fluorescence microscopy.

Analysis of signal waveform from a midsize liquid argon detector

The midsize single-phase liquid argon prototype detector, operating at the surface laboratory, is designed to measure scintillation light emitted by the liquid argon (LAr). The detector employs 42 8-inch photomultiplier tubes (PMT) to collect the light. By analyzing the waveform of the signal, important detector characteristics such as the slow decay time constant that characterizes the purity of the liquid argon can be obtained. To describe the signal waveform, a model, which takes into account the liquid argon emission decay times together with the TPB re-emission process as well as the signal reflection effects, is used. The TPB re-emission process is introduced using a three-exponential time structure. Additionally, experimental results provide comprehensive validation for a post-peak hump structure, which is attributed to signal reflection.

Characterisation and operations of the Multianode Photomultiplier Tubes for the LHCb RICH detectors

The upgraded LHCb RICH detectors are equipped with Multianode Photomultiplier Tubes, covering a total area of approximately four square metres. In order to achieve the same excellent hadron identification performance as during LHC Runs 1 and 2 at five times the instantaneous luminosity, the photon detectors have to be sensitive to single photons with repetition rates of up to 100MHz/cm2 and to have a very low noise count rate. The main properties of the photomultipliers are presented, together with the characterisation of an unexpected source of noise observed in the Hamamatsu R11265 Multianode Photomultiplier Tubes, extending up to several microseconds after the primary signal. The quality control results, the mitigation strategies for the aforementioned noise to perform optimal single-photon counting at 40 MHz, and the first operations of the RICH system are described.

Optimizing the design of ultrafast photomultiplier tubes.

Ultrafast microchannel plate (MCP) photomultiplier tubes are under active development. To obtain high gain, high spatial resolution, and good time performance, we comprehensively investigate the effects of the gap distances and voltages from cathode to MCPin and MCPout to anode in a systematic study using the finite integral technique and Monte Carlo method. A three-dimensional model is introduced to simplify the calculations. From the simulation results, a short gap distance and high gap voltage were determined to achieve good time performance, high spatial resolution, and high gain.

A 256 channel photon counting module using a square microchannel plate PMT in a tight packing envelop achieving

Photek have developed a square microchannel plate (MCP) photomultiplier tube (PMT) using 6 μm pore MCPs to achieve superior timing, compared to the previous generation which used 15 μm pores. The native anode pattern is 64 × 64, but for this module the pattern is ganged to a 16 × 16 design using an epoxy bonded PCB giving an anode size of 3.3 × 3.3 mm in a 53 × 53 mm active area. The electronic front-end is the TOFPET2d ASIC from Petsys Electronics, a combined amplifier/discriminator/TDC with 30 ps time bins and capable of 480 kHz per channel count rate, with sufficient dynamic range to allow for the gain variation inherent in large area MCP-PMTs. The outer envelope of the combined PMT and electronic front-end package allows for close packing on 4 sides with outer dimensions of 60 × 62 mm giving a 76% fill factor. We present results showing the combined performance of the PMT and TOFPET2d ASIC and the uniformity of single photon timing accuracy.