Photomultiplier Tube Research Articles

Effects of solar radiation on the performance of long-distance atmosphere-ocean laser communication links

We investigated the effect of solar radiation noise on the performance of a long-range atmosphere-ocean laser communication system. To model an inhomogeneous channel in the atmosphere-ocean system, a Monte Carlo (MC) simulation method was utilized in combination with measured underwater chlorophyll profiles. We conducted field measurements to accurately assess the effects of background noise, specifically solar radiation at different underwater depths and times. The influence of different scenarios on the system's signal-to-noise ratio (SNR) was then scrutinized based on the detector type. Additionally, a comprehensive analytical model was proposed for diverse background light noises, enabling the exploration of the effects of solar noise and Photomultiplier Tube (PMT) on the communication link's performance in terms of Pulse Position Modulation (PPM) demodulation symbol error rate (SER). The results indicate that expanding the receiver's field of view (FOV) from 1° to 15° can enhance the system's communication depth by 11 m, while increasing the receiver's radius from 1 cm to 20 cm can elevate the communication depth by 37 m. Moreover, the study investigates the impact of transmit power and the multi-aperture receiving technique on communication depth, providing valuable insights for designing atmosphere-ocean laser communication links and offering robust support for the practical implementation of the Free-Space Optical (FSO) - Underwater Optical Communication (UWOC) system.

TDCRPy: A python package for TDCR measurements

The TDCR (Triple-to-Double Coincidence Ratio) measurement technique is a primary standardization method used by metrology laboratories to accurately determine the activity of radioactive solutions, particularly for radionuclides unsuitable for traditional coincidence counting methods, such as pure beta emitters. The TDCR method leverages a liquid scintillation counter equipped with three photomultiplier tubes (PMTs). This paper introduces TDCRPy, a novel Python package developed by the BIPM, designed to calculate detection efficiency of liquid scintillation counters using Monte Carlo simulations and decay data evaluations from the Decay Data Evaluation Project (DDEP). The software simulates particle interactions within the liquid scintillation counter, utilizing pre-calculated probability distributions for energy deposition. Comparisons with the PENNUC/NUR code and tests with measurement from the BIPM.RI(II)-K1.Co-60 key comparison demonstrate the potential of TDCRPy. This open-source package is distributed at https://pypi.org/project/TDCRPy and available for collaborative development on GitHub https://github.com/RomainCoulon/TDCRPy, where detailed user documentation can be found.

Sensitivity of Frequency Domain Near Infrared Spectroscopy for Neurovascular Structure Detection in Biotissue Volume: Numerical Modeling Results.

Through numerical modeling, it has been determined that near infrared spectroscopy with a frequency domain approach can detect neurovascular structures with diameters from 0.5 mm at source-detector distances of 5-8 mm, depending on optical parameters and technical implementation of the method. Among the five classical machine learning methods considered, quadratic discriminant analysis is the most effective for detection. Furthermore, it has been demonstrated that the use of a photomultiplier tube and the registration of both amplitude and phase signal components exhibit the highest sensitivity. Spectroscopy can rival modern ultrasound for detecting arterial vessels. A cross-shaped probe configuration improves sensitivity, and the ratio of reduced scattering coefficient values at different wavelengths is informative for blood-filled vessel detection. These findings are consistent with and significantly extend previous experimental in vivo and in situ studies and could be valuable for intraoperative diagnostic tasks, particularly in neurosurgery.

A custom-made integrated system for thermoluminescence and radioluminescence spectroscopy

Thermoluminescence (TL) and Radioluminescence (RL) are widely used in dosimetry applications. We present a custom-built integrated system, designated LUMI22, for measuring TL, TL spectroscopy, RL, and RL as a function of temperature. LUMI22 includes a heating system based on Kanthal® A1 alloy (FeCrAl), a microcontroller to regulate the temperature ramps (e.g. 1–5 °C/s). To irradiate samples an X-ray tube (Moxtek 50 kV, 50 μA) is powered, controlled, and monitored by an FTC-200 standard controller. The dose rate at the sample position is 0.43 Gy/min. Light collection includes a Photomultiplier Tube (PMT, Hamamatsu H10493-012:HA, 185–850 nm). Additionally, a miniature fiber optic spectrometer (Ocean Optics, QE65000, range 200–1100 nm) coupled with a 1000 μm diameter fiber optic (QP1000- 2-UV-VIS) was employed for TL and RL spectroscopy measurements. To assess the functionality of the system, it was used to measure TL and RL from Al2O3:C,Mg, Al2O3:C and TLD-100 phosphors which have been previously well investigated. The measured TL and RL data were well compared to the published ones, confirming the functionality of the system.

Scintillation in Liquid Xenon for Gamma-Ray Medical Imaging: From Single Time-over-Threshold to Multi-Time-over-Threshold PMT Signal Measurements.

In this paper, a new light event acquisition chain in a three-gamma liquid xenon prototype for medical nuclear imaging is presented. The prototype implements the Multi-Time-Over-Threshold (MTOT) method. This method surpasses the Single-Time-Over-Threshold (STOT) by precisely determining both the number of vacuum ultraviolet (VUV) photons detected by each photomultiplier tube (PMT) and their arrival times for light signal measurement. Based on both the experimental and simulated results, the MTOT method achieved a 70% improvement in reconstructing photoelectrons (PEs) and enhanced the precision of the arrival time estimation by 20-30% compared with STOT. These results will enable an upgrade of the XEMIS2 (Xenon Medical Imaging System) camera, improving its performance as the imaged activity increases.

Three Photon Excited Image Scanning Microscopy for in-Depth Super-Resolution Studies of Biological Samples

Multiphoton laser scanning microscopy is a powerful tool for deep imaging of thick biological samples. Image scanning microscopy (ISM) has demonstrated significant improvements in the signal-to-noise ratio in confocal laser scanning microscopy, while at the same time improving upon the effectively attainable resolution. Two-photon excitation (2PE), combined with ISM, has been shown to allow for deep tissue imaging with enhanced resolution compared to 2PE microscopy. Three-photon excitation (3PE) has enabled record imaging depth and contrast for multiphoton imaging, due to the superior suppression of out-of-focus signal generation. In this paper, we demonstrate super-resolution 3PE ISM. This is achieved using a single-photon avalanche detector array, and 1040-nm pulses for 3PE of blue fluorescence. This method enables subdiffraction limited resolution imaging of biological samples stained with blue fluorescent markers, such as mouse myocardial and spinal cord tissues stained with 4′,6-diamidino-2-phenylindole. Deconvolution improves the resolving power further and allows for imaging with better than λ/8 resolution with respect to the 3PE wavelength λ. With the ISM pixel reassignment procedure, we demonstrate a resolution enhancement of ∼1.6 laterally, compared to the resolution attained using a photomultiplier tube in a non-descanned detection arrangement, and a factor of ∼1.8 enhancement in axial resolution. The experimentally measured three-dimensional point spread function volume is shrunk ∼4.4-fold, which is close to the theoretically expected enhancement. Published by the American Physical Society 2024

Leveraging the Nonlinearity of THz Photomultiplier Tubes for Enhanced Spectroscopic Sensitivity

Leveraging the Nonlinearity of THz Photomultiplier Tubes for Enhanced Spectroscopic Sensitivity

Deep Learning-Assisted Smartphone-Based Electrochemiluminescence Visual Monitoring Biosensor: A Fully Integrated Portable Platform.

A novel, portable deep learning-assisted smartphone-based electrochemiluminescence (ECL) cost-effective (~10$) sensing platform was developed and used for selective detection of lactate. Low-cost, fast prototyping screen printing and wax printing methods with paper-based substrate were used to fabricate miniaturized single-pair electrode ECL platforms. The lab-made 3D-printed portable black box served as a reaction chamber. This portable platform was integrated with a smartphone and a buck-boost converter, eliminating the need for expensive CCD cameras, photomultiplier tubes, and bulky power supplies. This advancement makes this platform ideal for point-of-care testing applications. Foremost, the integration of a deep learning approach served to enhance not just the accuracy of the ECL sensors, but also to expedite the diagnostic procedure. The deep learning models were trained (3600 ECL images) and tested (900 ECL images) using ECL images obtained from experimentation. Herein, for user convenience, an Android application with a graphical user interface was developed. This app performs several tasks, which include capturing real-time images, cropping them, and predicting the concentration of required bioanalytes through deep learning. The device's capability to work in a real environment was tested by performing lactate sensing. The fabricated ECL device shows a good liner range (from 50 µM to 2000 µM) with an acceptable limit of detection value of 5.14 µM. Finally, various rigorous analyses, including stability, reproducibility, and unknown sample analysis, were conducted to check device durability and stability. Therefore, the developed platform becomes versatile and applicable across various domains by harnessing deep learning as a cutting-edge technology and integrating it with a smartphone.

Development of a Data Overflow Protection System for Super-Kamiokande to Maximize Data from Nearby Supernovae

Abstract Neutrinos from very nearby supernovae, such as Betelgeuse, are expected to generate more than ten million events over 10 s in Super-Kamokande (SK). At such large event rates, the buffers of the SK analog-to-digital conversion board (QBEE) will overflow, causing random loss of data that are critical for understanding the dynamics of the supernova explosion mechanism. In order to solve this problem, two new data-acquisition (DAQ) modules were developed to aid in the observation of very nearby supernovae. The first of these, the SN module, is designed to save only the number of hit photomultiplier tubes during a supernova burst and the second, the Veto module, prescales the high-rate neutrino events to prevent the QBEE from overflowing based on information from the SN module. In the event of a very nearby supernova, these modules allow SK to reconstruct the time evolution of the neutrino event rate from beginning to end using both QBEE and SN module data. This paper presents the development and testing of these modules together with an analysis of supernova-like data generated with a flashing laser diode. We demonstrate that the Veto module successfully prevents DAQ overflows for Betelgeuse-like supernovae as well as the long-term stability of the new modules. During normal running the Veto module is found to issue DAQ vetos a few times per month resulting in a total dead-time less than 1 ms, and does not influence ordinary operations. Additionally, using simulation data we find that supernovae closer than 800 pc will trigger the Veto module, resulting in a prescaling of the observed neutrino data.

Upgrade of the LHCb RICH detectors and characterization of the new opto-electronics chain

The LHCb detector has been upgraded to manage a five-fold increase in the instantaneous luminosity delivered to the experiment during LHC Run 3 and to readout data at the full bunch crossing rate of 40 MHz. The enhanced LHCb RICH detectors now feature Multianode Photomultiplier Tubes (MaPMTs), covering a total area of approximately 4 square meters, and brand-new frontend electronics to comply with the trigger-less readout architecture. The opto-electronics chain is capable of detecting single photons at repetition rates of up to 100 MHz/cm2 while maintaining an exceptionally low noise. The RICH upgrade is comprehensively outlined, including details about the characterization and studies on the photon detection system. The stability and uniformity achieved by optimizing the parameters of the opto-electronics chain enable the RICH system to function successfully and to provide excellent charged hadron identification in high occupancy conditions.

The effects of acoustic disturbances and mechanical vibration on laminar premixed flames: A comparative study

The energy conversion between the combustion process and acoustic waves is very complex in high-performance propulsion systems, which may trigger large-amplitude combustion instabilities, potentially leading to severe vibration or structural damage. Both acoustic disturbances and mechanical vibration are found to be able to cause the combustion instability, but their differences on the influence of laminar premixed flames are still unknown. In this paper, a premixed methane flame burner was disturbed by either a loudspeaker or an electromagnetic vibration exciter, and the effects of their forcing frequencies and amplitudes on the dynamic responses of the premixed methane flame were evaluated. Specifically, the unsteady heat release rate was measured by a photomultiplier tube, and the flame dynamic behaviors were captured by a high-speed camera with image intensifier. Furthermore, the acoustic disturbances upstream of the flame was measured by the two-microphone method, and the structure vibration was measured by an accelerometer. Then, the flame transfer functions were obtained at various equivalence ratios and mean flow velocities. The results demonstrated that the premixed flame exhibited obvious band-pass filtering characteristics when subjected to external forcing, whether through a loudspeaker or an electromagnetic vibration exciter. In addition, increasing either acoustic or structure excitation amplitude to a large extent can make the flame respond in a nonlinear manner. However, when the flame was subjected to mechanical vibration, the peak frequency corresponding to the maximum gain of the flame transfer function had minimal sensitivity to variations in equivalence ratios and mean flow velocities. In contrast, the acoustic disturbances were more likely to induce the nonlinear flame responses and flame front wrinkling.

Modeling and field demonstration of water-to-ice wireless optical communication system based on highly-sensitive detectors.

In this paper, the first water-to-ice (W2I) wireless optical communication (WOC) system model is proposed and verified by laboratory and field experiments. The Monte Carlo (MC) approach is used to simulate the optical characteristics of ice and water, resulting in the channel impulse response and received optical power (ROP) distribution. The simulation results demonstrate that the substantial absorption and scattering of the ice and ice-water interface significantly affect the cross-medium communication. A comparative study in the laboratory validated the channel characteristics obtained from the simulation. Following this, a W2I WOC system based on photomultiplier tubes (PMTs) was established. Using the maximum ratio combining (MRC) technique, a net data rate of 400 Mbps was achieved in a 1-m laboratory tank, and a net data rate of 320 Mbps was achieved across a 1-m transmission distance in the reservoir. To reduce the computational complexity and realize practical system deployment, the orthogonal matching pursuit (OMP) approach is employed to compress the equalizer. The number of kernels in the Volterra equalizer is reduced by 36% in the laboratory experiment and 36.9% in the field experiment, respectively. The results of this study can serve as a reference for future deployment of W2I WOC systems.

Measurement of photo- and radio-luminescence of thin ThF[formula omitted] films

We conducted measurements on the photo- and radio-luminescence of thin ThF4 films in both the UV and visible ranges. In the UV range, we found that both luminescences are at a similar level as the internal dark counting noise of the photo-multiplier-tube (PMT). Our results suggest that thin ThF4 crystals could be used as a target for the search for 229mTh and as a medium for the future nuclear clock. The measurements indicate that using a small and thin ThF4 film can reduce background noise while maintaining the signal at the same level, achieved by increasing the 229Th enrichment. Our developed apparatus is now ready for direct measurements of 229mTh excitation and decay in ThF4.

Bio-Inspired Strategies Are Adaptable to Sensors Manufactured on the Moon.

Bio-inspired strategies for robotic sensing are essential for in situ manufactured sensors on the Moon. Sensors are one crucial component of robots that should be manufactured from lunar resources to industrialize the Moon at low cost. We are concerned with two classes of sensor: (a) position sensors and derivatives thereof are the most elementary of measurements; and (b) light sensing arrays provide for distance measurement within the visible waveband. Terrestrial approaches to sensor design cannot be accommodated within the severe limitations imposed by the material resources and expected manufacturing competences on the Moon. Displacement and strain sensors may be constructed as potentiometers with aluminium extracted from anorthite. Anorthite is also a source of silica from which quartz may be manufactured. Thus, piezoelectric sensors may be constructed. Silicone plastic (siloxane) is an elastomer that may be derived from lunar volatiles. This offers the prospect for tactile sensing arrays. All components of photomultiplier tubes may be constructed from lunar resources. However, the spatial resolution of photomultiplier tubes is limited so only modest array sizes can be constructed. This requires us to exploit biomimetic strategies: (i) optical flow provides the visual navigation competences of insects implemented through modest circuitry, and (ii) foveated vision trades the visual resolution deficiencies with higher resolution of pan-tilt motors enabled by micro-stepping. Thus, basic sensors may be manufactured from lunar resources. They are elementary components of robotic machines that are crucial for constructing a sustainable lunar infrastructure. Constraints imposed by the Moon may be compensated for using biomimetic strategies which are adaptable to non-Earth environments.

Determining the Position of Gamma-Ray Interaction Using Large Scintillation Detectors and the Least Number of Photomultiplier Tubes

Determining the position of interaction is of great interest for gamma-ray imaging in various nuclear applications. Among all gamma-ray detectors, scintillation detectors are commonly exploited for imaging purposes because they can be prepared in large dimensions and are economically affordable. In this work, the general shape of the measured gamma-ray spectra of two long and large-area plastic scintillation detectors are analyzed by artificial neural networks to determine the position of interaction in one and two dimensions (1D and 2D), respectively. The position of interaction was treated as the position of a 137Cs gamma-ray point source on the long and large-area scintillation detectors. Utilizing this method, only one photomultiplier tube (PMT) was used for 1D positioning of interaction in a 4 × 4 × 35-cm3 long plastic detector, while just two PMTs were applied for 2D positioning of interaction in a 50 × 50 × 5-cm3 large-area plastic detector. The position of interaction in the long detector was determined with a resolution of 1 cm and a mean absolute error of less than 1%, while a resolution of 5 cm with a mean absolute error of 13% was achieved for the large-area detector.

A simple and cost-effective strategy for electrochemiluminescence spectral determination

BackgroundElectrochemiluminescence (ECL), as a unique and powerful analytical technique, has been widely used in various fields. The determination of ECL spectra plays a crucial role in understanding ECL reaction mechanisms and conducting spectra-resolved ECL analysis. ECL intensity is typically detected using a photomultiplier tube, which offers high sensitivity for detecting extremely weak light signals but does not allow for spectral identification. Due to the time-dependent variation of ECL intensity caused by the applied potential and electrochemical reaction processes, it is challenging to perform ECL spectral detection using conventional wavelength-scanning spectrometers. ResultsIn this study, we present a straightforward and cost-effective ECL spectral detection strategy by incorporating an automatically controlled tunable optical filter device between a commonly used PMT detector and a specially designed ECL reaction cell. The effectiveness of this approach was confirmed through initial validation, where the spectrum of a green LED spotlight was measured and compared with a commercial spectrometer. In a dynamic system with stable ECL signals, the ECL spectrum of the typical Ru(bpy)32+/TPA system was rapidly acquired by adjusting the bandpass filters. To account for time-varying ECL signals in practical measurements, time-based correction algorithms were implemented to rectify variations in ECL intensity. By integrating time-based correction algorithms and an automatically controlled tunable optical filter device into a commonly utilized PMT detector, the rapid and sensitive ECL spectra determination was achieved. Experimental results demonstrated the reliability of the proposed strategy. SignificanceThis strategy is based on the widely used high-sensitivity PMT detection component, enabling the rapid and sensitive measurement of ECL spectra without altering the ECL detection hardware. It is simple, fast, efficient, and cost-effective, with the potential to be widely used for rapid ECL spectral detection and spectra-resolved ECL analysis.

An enhanced gated MCP-PMT for neutron detection in laser fusion experiments

The microchannel plate photomultiplier tube (MCP-PMT) is a photodetector that utilizes microchannel plates for signal amplification, offering rapid pulse response time of sub-nanosecond with a compact design and low dark current. A series of enhanced gated MCP-PMTs have been developed by incorporating a gating electrode between the photocathode and the MCPs, which have been employed in neutron detection during the double-cone ignition laser fusion experiment at the SGII Upgrade laser facilities.

Performance testing of a novel short axis photomultiplier tube for the HUNT project

Photomultiplier tubes (PMTs) with large-area cathodes are increasingly being used in cosmic-ray experiments to enhance detection efficiency. The optical modules (OMs) of the High-Energy Underwater Neutrino Telescope (HUNT) have employed a brand new N6205 20-inch microchannel plate photomultiplier tube (MCP-PMT) developed by the North Night Vision Science & Technology (Nanjing) Research Institute Co. Ltd. (NNVT). In order to make the 20-inch PMT fit into the 23-inch diameter pressure-resistant glass sphere, NNVT improved the internal structure of PMT and shortened the height of PMT by more than 10 cm. The first batch of these PMTs has been delivered for preliminary research work. This paper describes a specific PMT testing platform built for the first batch of 15 MCP-PMTs, and some performance parameters of PMT, such as peak-to-valley ratio, TTS and nonliniearity, are measured. The measurement results show that the new PMT still has good performance and can meet the requirements of HUNT project.

Development of the prototype for the SPARC hard X-ray monitor.

The SPARC tokamak will be equipped with a hard X-ray (HXR) monitor system capable of measuring the bremsstrahlung emission from runaway electrons with photon energies in excess of about 100keV. This diagnostic will detect the formation of runaway electron beams during plasma start-up and inform the plasma control system to terminate the discharge early to protect the machine. In this work, we present a 0D estimate of the HXR emission in SPARC during plasma start-up. Then we discuss the characterization of a prototype of the HXR monitor. The detector mounts a 1 × 1-in.2 LaBr3 inorganic scintillator coupled with a photomultiplier tube and has been tested with γ-ray sources to find its dynamic range. Finally, two possible modes of operation for spectroscopic and current mode measurements on SPARC are proposed.

Laser induced fluorescence using frequency modulated light.

The small signal-to-noise ratio (SNR) of conventional laser induced fluorescence (LIF) measurements using a continuous wave laser, either diode or dye, is typically overcome by amplitude modulating the laser at a specific frequency and then using lock-in amplification to extract the signal from measurement noise. Here, we present LIF measurements of the neutral helium velocity distribution function in an rf plasma using frequency modulated (FM) laser injection. A pulse train of 100% amplitude modulation is generated synthetically with a random sequence of pulse lengths. The FM signal then drives an acoustic optic modulator placed in the path of the injection beam in an LIF measurement. The signal from a fast photomultiplier tube is digitized and cross-correlated with the known modulation signal. The resultant FM-based LIF signal outperforms a conventional lock-in-based LIF measurement on the same plasma in terms of SNR and precision.