Number Of Photomultiplier Tubes Research Articles

Performance comparison of water Cherenkov detectors with different geometries

In the framework of the development of the SWGO experiment, we have performed a detailed study of the single unit of an extensive air shower observatory based on an array of water Cherenkov detectors. Indeed, one of the possible water Cherenkov detector unit configurations for SWGO consists of tanks, and to reach a high detection efficiency and discrimination capability between gamma-ray and hadronic air showers, different tank designs are under investigation. In this study, we consider and compare double-layer tanks with several sizes, shapes and number of photo-multiplier tubes (PMTs). Muons, electrons, and gamma-rays with energies typical of secondary particles in extensive air showers have been simulated entering the tanks with zenith angles from 0 to 60 deg. The comparison between different tank geometries was evaluated considering the number of photoelectrons produced by the PMTs, the detection efficiency, and the time resolution of the measurement of the first photon. We will show that with circular and hexagonal tanks better performance can be obtained than with the square ones, and that it improves for smaller tanks as expected.

Chasing a power supply in Siberia

Arthur Liberman’s Letter to the Editor on Cold War particle-physics collaborations (Physics Today, October 2020, page 12) reminded me of a visit I made in 1969 to Akademgorodok, a small research town near Novosibirsk, Siberia. At that time our Northeastern University research group had theoretically postulated, and done an initial experiment on, ρ–ω interference in the leptonic decay mode.11. R. G. Parsons, R. Weinstein, Phys. Rev. Lett. 20, 1314 (1968). https://doi.org/10.1103/PhysRevLett.20.1314 There were several interesting features to be experimentally or theoretically studied, and a flurry of work followed. We sought to do definitive experiments at the well-suited colliding-beams accelerator in Gersh Budker’s research facilities in Akademgorodok.During discussions with the facility’s director, Veniamin Siderov, concerning the proposed experiments, we compared the structure of the Novosibirsk research group with that of the Northeastern group. The numbers that emerged gave significant insight to the hurdles faced by physics researchers in the Soviet Union.Northeastern’s high-energy research group consisted of five PhDs and seven support technicians. When I requested that Siderov provide comparable information about his facility, he replied that he had 2000 technicians. I assumed that he had misunderstood my question, but he actually did have that many technicians working for him. To help me understand the staggering difference, he described the procedure he would follow when he needed, for example, a power supply.In the US one would simply go out and buy a power supply, but such devices were not available on the Soviet market, and Siderov had no access to hard currencies. He would have to set up a production line in a subgroup of his 2000 technicians, and they would produce perhaps 100 power supplies. He would then act as a vendor of the devices—for several years if need be—to support his technicians and make purchases of his own from other similar manufacturing centers. The amount of organization, energy, and manpower required to obtain a power supply was staggering.I had come prepared to discuss the details of the proposed experiment, but Budker was already expert in the details of ρ–ω interference. Instead he wanted to discuss the proposed experimental setup—in particular, the number of photomultiplier tubes and power supplies. He agreed to make the accelerator available for the proposed experiment on one condition—that after completion of the measurements, the equipment would be left at his lab.I carried that proposition back to my supporting agency, which had previously supplied support for Soviet experiments in the US. However, the arrangement was not approved; it amounted to the US paying for Soviet beam time while Soviet researchers got US beam time for free.ReferenceSection:ChooseTop of pageReference <<1. R. G. Parsons, R. Weinstein, Phys. Rev. Lett. 20, 1314 (1968). https://doi.org/10.1103/PhysRevLett.20.1314, Google ScholarCrossref© 2021 American Institute of Physics.

Study on Reactor Neutrino Directionality Search Utilizing Vertex Information Reconstructed by PMT Operating State in a Liquid Scintillator Detector

The properties of neutrinos are not well known because they weakly interact with surrounding matter. Recently, several interesting results and phenomena have been measured using reactor neutrinos. Although there are various types of detectors that detect neutrino signals, they generally use photomultiplier tubes (PMTs) to collect data. In particular, signals obtained from each PMT surrounding a detector are used to reconstruct a vertex of an incident neutrino in the detector. However, if a number of PMTs are out of operation from the initial installation, the performance of the PMT or its operation efficiency may be changed over time. This may affect the information for the reconstructed vertex of an incident neutrino, which can have a direct impact on results that utilize the reconstructed vertex information. This article briefly describes the change of reconstructed vertex according to operating status of PMTs around the reactor neutrino detector by using a Monte Carlo (MC) simulation based on a cylindrical detector equipped with liquid scintillator. The MC simulation for this analysis needs a moderate number of central processing units (CPUs) and cores. Therefore, various resources and servers at a supercomputing center were used. Our results can be used to more accurately conduct research related to neutrino direction using PMT information in the future.

Deep Learning the Effects of Photon Sensors on the Event Reconstruction Performance in an Antineutrino Detector

We provide a fast approach incorporating the usage of deep learning for studying the effects of the number of photon sensors in an antineutrino detector on the event reconstruction performance therein. This work is a first attempt to harness the power of deep learning for detector designing and upgrade planning. Using the Daya Bay detector as a case study and the vertex reconstruction performance as the objective for the deep neural network, we find that the photomultiplier tubes (PMTs) at Daya Bay have different relative importance to the vertex reconstruction. More importantly, the vertex position resolutions for the Daya Bay detector follow approximately a multiexponential relationship with respect to the number of PMTs and, hence, the coverage. This could also assist in deciding on the merits of installing additional PMTs for future detector plans. The approach could easily be used with other objectives in place of vertex reconstruction.

Very low power, high voltage base for a Photo Multiplier Tube for the KM3NeT deep sea neutrino telescope

The described system is developed in the framework of a deep-sea submerged Very Large Volume neutrino Telescope where photons are detected by a large number of Photo Multiplier Tubes. These PMTs are placed in optical modules (OM). A basic Cockcroft-Walton (CW) voltage multiplier circuit design is used to generate multiple voltages to drive the dynodes of the photomultiplier tube. To achieve a long lifetime and a high reliability the dissipation in the OM must be kept to the minimum. The design is also constrained by size restrictions, load current, voltage range, and the maximum allowable ripple in the output voltage. A surface mount PMT-base PCB prototype is designed and successfully tested. The system draws less than 1.5 mA of supply current at a voltage of 3.3 V with outputs up to -1400 Vdc cathode voltage, a factor 10 less than the commercially available state of the art.

Design of a High Performances Small Animal PET System With Axial Oriented Crystals and DOI Capability

In most positron emission tomography (PET) systems dedicated to small animal imaging, the geometry of the detector module is based on a block structure where the crystal elements are coupled to a reduced number of photomultiplier tubes (PMT). In this configuration, the spatial resolution and the detection efficiency depend on the crystal dimensions and thus there is a correlation between these two figures of merit. In this paper, we present a method already used by Ter-Pogossian et al in the 1970s allowing the spatial resolution and the detection efficiency to be independent of each other. The crystals are oriented in the axial direction readout on both sides by individual photodetector channels. The spatial resolution in the transverse plane is driven by the crystal section and the spatial resolution in the axial direction is proportional to the contrast of the light collected on both sides of the crystal. The detection efficiency depends on the number of radial crystal layers and the geometry of the system. With the perfect knowledge of the interaction depth, the inner diameter of the PET system can be reduced to a minimum value leading to an increase in detection efficiency. We investigate two particular geometries dedicated to mouse and whole purpose studies and based on the same detection module. Each module consists on a matrix of 32 times24 LYSO:Ce crystals of 1.5 mm times 1.5 mm times 25 mm each read at both ends by a Photonis Corp multichannel plate photodetector. The surface treatment is optimized to reach a volumetric spatial resolution of 1 mm3. The detection efficiency of each system is evaluated using Monte Carlo simulation. The mouse and whole purpose systems are based on 4 and 6 modules with an inner diameter of 61.2 mm and 103.2 mm where the axial extent is 25 mm leading to a detection efficiency of 18% and 13%, respectively. This geometrical configuration leads to a detection efficiency close to the system solid angle with a volumetric spatial resolution of 1 mm3 .

Design and development of high-sensitive vacuum photodetectors in the National Research Institute “Electron”

The last years' developments of Photomultiplier Tubes (PMTs) in the “Electron” National Research Institute are presented. There were a number of PMTs with superior characteristics developed during the last decade. Among these are such devices as PMTs with low radiation background, microchannel plate PMTs (MCP-PMT), PMTs with GaAs photocathodes. The latest developments of the new kind and innovative range of photodetectors, and such novel devices as Fine-Mesh PMTs for high magnetic field environment and proximity focused Hybrid PMTs (HPMT) with an electron bombarded p-i-n diode are also discussed.

Parameterisation of the angular response of the R1408 Hamamatsu eight-inch photomultiplier tube to be used in the Sudbury Neutrino Observatory

This paper describes measurements made on Hamamatsu R1408 8-in. photomultiplier tubes in order to parameterise the cesium bialkali photocathode in terms of a complex refractive index n ̃ and a thickness τ. The extracted parameters have been used to predict the angular response of the photomultiplier tubes, and this prediction has been experimentally verified. Measurements were taken on a number of photomultiplier tubes from the start and end of a 10 000 photomultiplier tube production run to investigate any systematic drift in parameterisation.

A large fast water Cherenkov counter

A description is given of a large-volume Cherenkov counter with diffuse reflecting inside walls. Particular attention is given to the timing properties and it is shown that the chosen combination of the reflectivity of the walls and the number of photomultiplier tubes gives an output rise time of about 12 ns. The performance of the counter in two experiments is discussed.

The Use of Photomultiplier Tubes for Photon Counting

A number of photomultiplier tubes have been assessed for application in experiments where the counting of individual photoelectrons from the photocathode is necessary or advantageous. Pulse height distributions, signal-to-noise-in-signal ratios, over-all quantum-counting efficiencies, time dependent statistical correlations, and dark current properties have been investigated and compared with theoretical expectations. Amajor finding has been the general low value of over-all quantum-counting efficiency. Direct measurements of this figure have not, to our knowledge, been published previously. A second conclusion has been that, although there seems to be no reason why high performance with respect to each of the features considered should not be achieved in a single tube, we have not yet found one in which this is so.