Microchannel Plate Research Articles

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.

Hardware Implementation and Testing of 4-Channel Fast Electronics for an MCP Detector

Hardware Implementation and Testing of 4-Channel Fast Electronics for an MCP Detector

$$^{10}$$B-doped MCP detector developed for neutron resonance imaging at Back-n white neutron source

$$^{10}$$B-doped MCP detector developed for neutron resonance imaging at Back-n white neutron source

Development of an X-ray ionization beam position monitor for PAL-XFEL soft X-rays.

The Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL) operates hard X-ray and soft X-ray beamlines for conducting scientific experiments providing intense ultrashort X-ray pulses based on the self-amplified spontaneous emission (SASE) process. The X-ray free-electron laser is characterized by strong pulse-to-pulse fluctuations resulting from the SASE process. Therefore, online photon diagnostics are very important for rigorous measurements. The concept of photo-absorption and emission using solid materials is seldom considered in soft X-ray beamline diagnostics. Instead, gas monitoring detectors, which utilize the photo-ionization of noble gas, are employed for monitoring the beam intensity. To track the beam position at the soft X-ray beamline in addition to those intensity monitors, an X-ray ionization beam position monitor (XIBPM) has been developed and characterized at the soft X-ray beamline of PAL-XFEL. The XIBPM utilizes ionization of either the residual gas in an ultra-high-vacuum environment or injected krypton gas, along with a microchannel plate with phosphor. The XIBPM was tested separately for monitoring horizontal and vertical beam positions, confirming the feasibility of tracking relative changes in beam position both on average and down to single-shot measurements. This paper presents the basic structure and test results of the newly developed non-invasive XIBPM.

Analysis of the limits of applicability of photomultiplier as part of a laser Doppler anemometer

This paper considers the use of laser Doppler anemometry methods for non-contact measurement of the velocity of a moving medium in various phase states. It notes the specifi city of conditions of application of laser Doppler anemometers, in that in a number of cases there are restrictions on the use of photomultipliers. In order to find an alternative to the classic photomultiplier of a laser Doppler anemometer, three types of photomultipliers were investigated: classic electric vacuum; silicon avalanche multipixel; with microchannel plate. Physical experiments were conducted to measure the velocity of aero- and hydrodynamic fl ows by laser Doppler anemometer with photomultipliers of three types. The velocities of a rotating glass disk, aerodynamic fl ow in a channel of rectangular cross-section, and aerosol flow, as well as hydrodynamic flooded jet, were measured. The obtained experimental data were analyzed according to the criteria for assessing the quality (efficiency) of operation and finding the limits of applicability of the specified photomultipliers. Based on the physical properties of the studied photomultipliers, their efficiency indicators in various experiments are explained. The boundaries of the effective use of these photomultipliers in a wide class of physical experiments are determined. The results obtained are important for researchers involved in the study of aero- and hydrodynamic flows, where accurate and reliable measurements of flow velocity are required. The choice of an optimal photomultiplier tube for the laser anemometer allows increasing the accuracy and ease of obtaining experimental data and reducing the cost of the final equipment.

Experimental investigation of heat transfer and pressure drop in copper manifold microchannel heat sinks

Over the past decade, various two-phase cooling solutions have been implemented to dissipate power in high heat flux electronic components. The manifold microchannel heat sink is an efficient thermal management solution that reduces heat resistance while also limiting the pumping power. However, there is limited work available on small form factor manifold microchannels with traditional heat sinking materials like copper. In this study, an experimental investigation is conducted to evaluate the heat transfer and pressure drop performance of copper manifold microchannel heat sinks using an environmentally friendly refrigerant, R1233zd(E), as the working fluid. A microchannel plate and a manifold plate, both made of oxygen-free copper, are sandwiched together to form the manifold microchannel test sample assembly. To compare the effects of geometric parameters, a total of six manifold microchannel test samples are investigated, including two types of manifold plates and three types of microchannel plates. The experiments are performed with refrigerant mass flow rates ranging from 5 to 15 g/s and inlet subcooling temperatures ranging from 3 to 10 K. The heat transfer coefficient increases with a decreasing number of manifolds and with an increase in the number and width of the microchannels. The pressure drop decreases in configurations with more microchannels, more manifolds, and larger microchannel widths. Compared to traditional microchannels, manifold microchannels significantly reduce the total pressure drop. However, their heat transfer performance at higher heat flux conditions is limited by the trapped bubbles phenomena. In comparison to traditional microchannels, manifold microchannels demonstrate much higher performance in dissipating the same amount of heat flux while limiting pumping power, as indicated by the COP.

Single electron charge spectra of 8-inch high-collection-efficiency MCP-PMTs

The microchannel plates (MCP) can serve as the electron amplifier of the photomultiplier tubes (PMT). The collection efficiency of the newly developed 8-inch MCP-PMT for the Jinping Neutrino Experiment is maximized thanks to the high-secondary-emission coating. The resulting single electron response (SER) charge distribution deviates from the Gaussian distribution in large charge regions. To understand the nature of the jumbo-charged SER, we designed a voltage-division experiment to quantify the dependence of the MCP gain on the energy of incident electrons. Combining the relationship with the Furman probabilistic model, we reproduced the SER charge spectra by introducing an additional amplification stage on the input electrode of the first MCP. Our results favor a Gamma-Tweedie mixture to describe the SER charge spectra of the MCP-PMTs.

Multi-U-Style micro-channel in liquid cooling plate for thermal management of power batteries

In order to cope with the problem of the shortening of automotive power battery life and the reduction of occupant safety due to the large amount of heat generated by automotive power batteries of high-energy–density at high discharge rates, this paper proposes a Multi-U-Style micro-channel in the liquid-cooled plate (Multi-U), based on the heat generation characteristics and temperature distribution of automotive power batteries. The impact of different Multi-U arrangements on the cooling performance of the batteries is explored, and the results indicate that the cooling performance is better with the side face arrangement. Compared to main face 1, the maximum temperature (Tmax) and maximum temperature difference (ΔTmax) of the batteries decrease by 2.40 K and 2.50 K, respectively. In addition, through a comparative analysis with typical serpentine micro-channel chilled plate (SMCP) and parallel micro-channel chilled plate (PMCP), Multi-U exhibits superior overall performance. Furthermore, the influence of equally incremental and decreasing channel width of Multi-U from the center to the periphery on cooling performance of the batteries is explored. It turns out that when the channel width is equally decreasing 1 mm Multi-U (D 1 mm), the heat dissipation is most effective. Finally, the critical parameters of the Multi-U are optimized to improve the power density of batteries. The impact of critical parameters of the Multi-U on the cooling performance of the batteries is studied through orthogonal experiments. The optimal parameter combination is found to be a channel width (W) = 12 mm, channel thickness (H) = 6 mm, inlet mass flow rate (F) = 0.02 kg∙s−1, and inlet coolant temperature (T) = 292.15 K. Compared to the original Multi-U, the Tmax and ΔTmax of batteries decrease by 5.83 K and 0.06 K, respectively, while the pressure drops decrease by 89 %.

Balance regulation of heat transfer and flow performance in convective heat exchange process of microchannel plates

As high-performance computing devices continue to evolve toward miniaturization and integration, chip performance has increased significantly. However, chip dimensions are simultaneously shrinking. This trend has led to more challenging high heat flux density issues. Microchannel liquid cooling is an effective way to solve this issue, where the most critical aspect is the balance regulation of heat transfer performance and fluid dynamics. To address this challenge, this study initially divided a complete microchannel plate into two parts: an inlet distribution chamber (IDC) and an array structure. Subsequently, anentransy dissipation rate modeland apumping power consumption modelwere established for themicrochannel inlet diversion chamber, and an optimization design was carried out. This solved the problems of the optimal branch level and optimal channel size for designing the microchannel IDC within a given space. Next, themicrochannel array structurewas optimized to minimize boththermal resistanceandoverall flow resistance. This approach facilitated proactive optimization design for the microchannel array structure within the specified space. Finally, the independently optimizedinlet diversion chamberandarray structurewere combined into a complete optimized microchannel plate. Several comparative structures were also designed under the same constraints. Experimental research was conducted to validate the reasonableness of the optimization. The results indicated that, compared to randomly designed structures, the average overall performance of the optimized structure within the study scope hadincreased by at least 1.16 times, with the highest improvement reaching4.29 times. This study provides a theoretical reference for the active optimization design of microchannel plates in convective heat exchange process.

Designed a photomultiplier tube X-ray framing camera based on pulse dilation technology

During the past decade, many diagnostic instruments have been developed that utilize electronic pulse dilation to achieve temporal resolution in the sub-10 ps range. The motivation behind these development efforts was the need for advanced diagnostics in high-density physics experiments around the world. This technology converts the signal of interest into a free electron cloud, which is accelerated into a vacuum drift space. The acceleration potential varies over time and causes axial velocity dispersion in the electron cloud. This velocity dispersion is converted into time separation after electrons pass through drift space. Then, traditional time resolved methods were used to detect free electrons, and the effective temporal resolution was magnified many times. A gated microchannel plate (MCP) X-ray framing camera based on pulse-dilation technology has been designed and manufactured in the paper. Here, we discuss design details and applications of these instruments. The temporal resolution measured without using broadening technology is approximately 78 ps. When the excitation pulse is applied to the PC, the pulse dilation technique is used to increase the measured temporal resolution to 9 ps. The propagation speed of gated pulses in MCP microstrip lines was measured using fiber bundle method, which is approximately 1.8 × 108 m/s.

Systematic approach to measure the performance of microchannel-plate photomultipliers

In this paper, we present our approach to systematically measure numerous performance parameters of microchannel plate photomultiplier tubes. The experimental setups, the analyses and selected results are discussed. Although the techniques used may be different in other locations, the document is intended as a guide for comparable measurements with other types of microchannel plate photomultiplier tubes. Measurements are shown for the following performance parameters: spectral and spatial quantum efficiency, collection efficiency, gain as a function of voltage, position and magnetic field, time resolution, rate capability and lifetime. By using a dedicated 3-axis stepper and an FPGA-based data acquisition system, also inner PMT parameters are measured as a function of the active area, such as relative detection efficiency, dark count rate, time resolution, recoil electron and afterpulse distributions, as well as charge sharing and electronic crosstalk. In addition, some of the parameters are investigated inside a strong magnetic field. For many of these measurements, the change of most setup parameters and the subsequent analysis can be controlled semi-automatically by software scripts.

Scanning-assisted focal plane-detection system for a sector-field mass spectrometer - Part-I: Simulation and data processing

In this paper, a novel detection system, the Scanning-Assisted Focal Plane-Detection System (SAFPDS), is proposed as a focal plane detector for sector-field mass spectrometers. The principle of SAFPDS is to decouple the spatial resolution and local count rate of the microchannel plate (MCP) focal plane-detection system in order to enhance the local count rate and dynamic range limited by the MCP. This decoupling is achieved by deflecting ions along the vertical direction of the focal plane detector using an ion deflector during acquisition. Simulations of the SAFPDS are reported for optimal geometrical design, operation, and performance. Additionally, a dedicated novel data processing protocol for deriving a representative mass spectrum from the 3D-recorded data obtained with SAFPDS is developed in combination with the SAFPDS hardware. Our study shows that this protocol effectively enhances the spectrometer's Figure of Merit (FOM), defined as the integral of the mass resolution (m/Δm) over the relevant mass range, by a factor of 2.4. Furthermore, the evaluation of the spectrometer equipped with SAFPDS highlights its capability to enhance the local count rate and dynamic range of sector field mass spectrometers with an MCP-based detector by at least one order of magnitude. Importantly, this enhancement is achieved with a deterioration in mass resolving power that remains below 30%, which we consider acceptable given the significant improvements in local count rate and dynamic range.

Advances in the Large Area Picosecond Photo-Detector (LAPPDTM): 8" × 8" MCP-PMT with Capacitively Coupled Readout

We present advances made in the Large Area Picosecond Photodetector (LAPPD), an 8" × 8" microchannel plate photomultiplier tube (MCP-PMT), since pilot production was initiated at Incom, Inc. in 2018. The Gen-I LAPPD utilizes a stripline anode for direct charge readout. The novel Gen-II LAPPD employs an internal resistive thin-film which capacitively couples to a customizable external signal readout board, streamlining production and increasing customer flexibility. The Gen-II LAPPD, with an active area of 373 cm2, is capable of high single photoelectron (PE) gain of ∼107, low dark rates (∼1 kHz/cm2), single PE (SPE) timing resolution of ∼65 ps, and 𝒪(mm) position resolution. Coupled with a UV-grade fused silica window, the LAPPD features a high quantum efficiency (QE) bialkali photocathode of >30% at 365 nm with spectral response down to ∼165 nm. The LAPPD is an excellent candidate for electromagnetic calorimeter (ECAL) timing layers, photon-based neutrino detectors, high energy collider experiments, medical imaging systems, and nuclear non-proliferation applications.

Single-exposure elemental differentiation and texture-sensitive phase-retrieval imaging with a neutron-counting microchannel-plate detector

Single-exposure elemental differentiation and texture-sensitive phase-retrieval imaging with a neutron-counting microchannel-plate detector

Static Mode Testing of S-20 Optical Streak Camera

The spectral response of the S-20 streak camera ranges from 350 to 850 nanometers. The streak camera consists of a streak tube and an image intensifier tube followed by a CCD camera. The optical streak camera can be operated in three modes viz. static mode, gated mode, and dynamic mode. In static mode, various electrodes are checked by applying suitable DC voltages For this purpose, a high-voltage biasing network is developed. Gated mode operation is introduced to improve signal-to-noise ratio. So, the Micro Channel Plate (MCP) of the image intensifier tube will be activated with the gated signal.

PICMIC-0: a 5 μm pitch hexagonal pixel sensor with an original tri-axis readout

We present in this paper a new sensor called PICMIC-0 that is intended to exploit the intrinsic spatial resolution of the MicroChannel Plate (MCP) detectors. Manufactured using 6-metal TowerJazz 180 nm wafer technology, the sensor features hexagonal charge collection pixels on the top metal layer with a pitch of 5 μm and covering an area of 7.4 × 6.4 mm2. The 2 million of the pixels of this sensor are not read out individually.Each pixel is connected to a straight-line in either 0°, 120° or -120° orientation, in which a current is produced in case of a hit. Each of these readout strip-lines is connected to a readout cell which receives this current, amplifies it using a current mirror and converts it into a digital signal by means of a current comparator. The data is collected from the digital outputs of the readout cells using a priority encoder readout scheme and transmitted in frames of 400 ns. This projective readout system reduces the number of channels to be read out from 2 million pixels to 2556 readout cells integrated within the pixel matrix. Using three projections reduces the ambiguity in case of multiple hits.

Deep learning-based spatiotemporal multi-event reconstruction for delay line detectors

Accurate observation of two or more particles within a very narrow time window has always been a challenge in modern physics. It creates the possibility of correlation experiments, such as the ground-breaking Hanbury Brown–Twiss experiment, leading to new physical insights. For low-energy electrons, one possibility is to use a Microchannel plate with subsequent delay lines for the readout of the incident particle hits, a setup called a Delay Line Detector. The spatial and temporal coordinates of more than one particle can be fully reconstructed outside a region called the dead radius. For interesting events, where two electrons are close in space and time, the determination of the individual positions of the electrons requires elaborate peak finding algorithms. While classical methods work well with single particle hits, they fail to identify and reconstruct events caused by multiple nearby particles. To address this challenge, we present a new spatiotemporal machine learning model to identify and reconstruct the position and time of such multi-hit particle signals. This model achieves a much better resolution for nearby particle hits compared to the classical approach, removing some of the artifacts and reducing the dead radius a factor of eight. We show that machine learning models can be effective in improving the spatiotemporal performance of delay line detectors.

Spatial and Temporal Detection of Ions Ejected from Coulomb Crystals.

Coulomb crystals have proven to be powerful and versatile tools for the study of ion-molecule reactions under cold and controlled conditions. Reactions in Coulomb crystals are typically monitored through a combination of in situ fluorescence imaging of the laser-cooled ions and destructive time-of-flight mass spectrometry measurements of the ejected ions. However, neither of these techniques is able to provide direct structural information on the positions of nonfluorescing "dark" ions within the crystal. In this work, structural information is obtained using a phosphor screen and a microchannel plate detector in conjunction with a Timepix3 camera. The Timepix3 camera simultaneously records the spatial and temporal distribution of all ions that strike the phosphor screen detector following crystal ejection at a selected reaction time. A direct comparison can be made between the observed Timepix3 ion distributions and the distributions established from SIMION simulations of the ion trajectories through the apparatus and onto the detector. Quantitative agreement is found between the measured Timepix3 signal and the properties of Coulomb crystals assigned using fluorescence imaging─independently confirming that the positions and numbers of nonfluorescing ions within Coulomb crystals can be accurately determined using molecular dynamics simulations. It is anticipated that the combination of high-resolution spatial and temporal data will facilitate new measurements of the ion properties within Coulomb crystals.

Spatial extension of the transient gain drop in a microchannel plate for a single-pulse irradiation

It is widely recognized that a microchannel plate gain drops temporarily after a particle initiates an electron avalanche and that a large amount of charge is extracted from the channel. Electron multiplication is expected to deplete the charges from the microchannel and produce depleted charges (wall charges), and this gain drop is known to persist until charges are replenished. In addition, it was reported that a gain drop occurs not only in the activated channels, where the electrons are multiplied, but also in the surrounding channels. A proposed mechanism for this phenomenon is suggested that the wall charges in the activated channels change the electric field in the surrounding channels, which affects the electron multiplications. In this study, the spatial extent of the gain drop of a chevron microchannel plate detector was evaluated by measuring gains as a function of distance from an activated channel. The experiment used two ultraviolet pulses with different beam sizes, which initially activated one channel and the six neighboring channels with carefully focused laser light, and then applied another light pulse to the surrounding 900 μm × 30 μm area. The gain of each channel was measured using a charge-coupled device camera, and the change in gain as a function of the output charge for the laser pulse was analyzed. A gain drop of 20% was observed at a channel located 110 μm far from the initial activated channel when the output charge was 4 pC. The obtained relationship between the radius of gain drop area and the output charge for the laser pulse was in good agreement with that predicted from the transverse electric field due to the wall charges by computational analysis.

The position resolution of the Gas Microchannel plate Pixel Detector

The Gas Microchannel plate Pixel Detector (GMPD) is purposefully designed and manufactured for astrophysical X-ray polarization detection, slated for use in various space missions such as the Cosmic X-ray Polarization Detector (CXPD) CubeSat, Low Energy Polarimeter Detector (LPD/POLAR-2), and the Chasing All Transients Constellation Hunters (CATCH). Past research has explored the polarization and spectral performance of GMPD. This study, for the first time, experimentally investigates its imaging characteristics to validate its imaging capabilities. Utilizing a deconvolution method, we measured the position resolution of GMPD, revealing distinctions in the detector's imaging capabilities for X-rays of varying energies and in orthogonal directions. These research findings will provide targeted insights for optimizing the photoelectron track reconstruction algorithm and correcting systematic effects in polarization measurements for future applications of GMPD.