Hiroyuki Kyushima

The development of flat panel PMT

In High Energy Physics (HEP) experiment and scintillation counting application, a photodetector, which can cover large area and has small dead space, has been desired. It should be compact and should have multi-anode in some cases. Hamamatsu has developed a Flat Panel Photomultiplier (PMT) to meet the demand. If many of Flat Panel PMTs are placed closely, they can cover large area as one photodetector. The Flat Panel PMT has 51.7/spl times/51.7/spl times/12.4 mm metal package and 8/spl times/8 matrix multi-anode. Some prototypes were made, and it was confirmed that a ratio between external size and useful area was 90% and gain of 3/spl times/10/sup 5/ was achieved. Its structure and basic feature are discussed in this paper.

Improvement of 20 in. diameter photomultiplier tubes

Abstract The quality of the 20 in. photomultiplier tubes (Hamamatsu R1449) has been greatly improved over the required specifications for using them in the 50 000 ton imaging water Cherenkov detector, Super-Kamiokande. In particular, the resolution of the timing response for single-photoelectron light has been reduced to ∼ 3 ns (1σ width), and a clear single-photoelectron peak can be seen in the pulse height distribution. The obtained characteristics of the new tubes will make it possible to upgrade the performance of the Super-Kamiokande detector. The goal of the improvement, the procedure for designing the new tubes and the measuring results concerning the characteristics are described in detail.

Photomultiplier tube of new dynode configuration

In spectroscopic analysis, radiation detection, and medical application fields, portable instruments requiring high accuracy and high sensitivity are being developed. Since conventional photomultiplier tube (PMT) envelopes are made of glass and are large in size, it is difficult to downsize instruments. PMTs are mainly used for high accuracy instruments, while solid state detectors are employed for general purpose, or compact instruments. Hamamatsu recently developed the compact PMT R5600 series, which is downsized to the same dimensions as a solid state detector while maintaining the same performance, high sensitivity and high speed as the conventional PMTs. >

Development of a high-sensitivity UV photocathode using GaN film that works in transmission mode

We developed a high-sensitivity GaN photocathode that works in transmission mode. It has 40.9 % quantum efficiency at 310 nm wavelength. Conventional GaN photocathodes, both transmission mode and reflection mode, are made on a sapphire substrate using metal-organic vapor phase epitaxy (MOVPE). In reflection mode, a GaN photocathode has very high quantum efficiency (QE) of over 50 %. However, in transmission mode, the quantum efficiency of a GaN photocathode was about 25 % at 240 nm with this technique. Therefore, we developed a new GaN photocathode using a glass-bonding technique, where a GaN thin film was bonded to a glass face plate. We found out that constituting an Al- GaN layer on the light incidence side of the photocathode surface provided higher QE than a sole GaN layer type for transmission mode. We focused on the band bending of the photocathode, and analyzed QE for both transmission mode and reflection mode. We then verified the effectiveness of the AlGaN layer using the results from the analysis. The high-sensitivity UV photocathode will be used for flame detection, corona discharge observation, and other UV imaging.

Development of large-aperture hybrid avalanche photo-detector

This paper reports on the R&D status of a large-aperture Hybrid Avalanche Photo-Detector (HAPD). We have developed a 13-inch aperture HAPD and its readout system. The HAPD is a photo detector expected to replace the photomultiplier tube (PMT) in next-generation imaging water Cherenkov detectors such as Hyper Kamiokande. We will present the recent progress made in readout system development, new compact high-voltage power supply, and a new 8-inch aperture HAPD.

New photodetector metal package photomultiplier tube

We have developed two types of metal package photomultiplier tube (PMT): the R5600 series and the R5900 series. The R5600 series is a compact PMT that incorporates an 8-stage electron multiplier (metal channel dynode) constructed with stacked thin electrodes into a TO- 8 type metal can package. The R5900 series consists of the same thin electrodes as the R5600 series in a 28 mm square 20 mm height metal package. The metal channel dynode is supported by computer simulation of electron trajectory and fine etching technique.

A compact position-sensitive detector for PET

A high resolution BGO block detector has been developed for a positron emission tomography (PET) system. The detector consists of a newly developed compact position-sensitive photomultiplier tube (PS-PMT) and an 8(X)/spl times/4(Y) BGO array of which element size is 2.8 mm/spl times/6.8 mm/spl times/30 mm. The PS-PMT has ten stages of metal channel dynodes and crossed-wire anodes in a 28 mm square/spl times/20 mm high metal package. The performance of the PS-PMT and the block detector was evaluated in terms of applicability to PET. The coincidence timing resolution was 4.4 ns FWHM and 9.5 ns FWTM, and the energy resolution was about 30% for 511 keV /spl gamma/-rays, with the PS-PMTs coupled to single BGO segments. The spatial resolution of the block detector was evaluated by measuring the detector response functions (DRFs) for each BGO segment. The average FWHM values of the DRFs were 3.0 mm in the X direction, and 6.8 mm in the Y direction. Count rate performance of the block detector was measured at different activity levels, when no distinct mispositioning in crystal coding was seen at count rates up to 100 kcps. A compact 3D-PET system dedicated to animal studies was designed by adopting the position-sensitive detectors.<<ETX>>

Development of large-aperture hybrid photo-detector and readout system

We have undertaken the development of a large scale hybrid photo-detector (HPD) and new readout system comprising an ASIC preamplifier, an analog memory cell (AMC) and an FPGA (DSP) which, together, are intended to be the next generation water Cherenkov detector. We have fabricated a 13-inch HPD and have confirmed the S/N of ~10 and the time resolution better than 1 ns (sigma) for a single photon level signal. We have made and evaluated the performance of prototypes of a bipolar process charge sensitive ASIC preamplifier and 64-depth AMC to be used in the readout system

Metal package photomultiplier tube

The Metal Package PMT R5600U series, a size of 15 mm diameter and 10 mm height, has been developed. Its appearance is the same as TO-8 type solid state device and it has as high sensitivity and speed as a conventional PMT. There are two important key components for the development of this tube. They are the metal envelope same as the package of TO-8 and 8 stage-Metal Channel Dynode for electron multiplier. These two features, supported by computer simulation of electron trajectory and fine etching technique, realized new compact design.<<ETX>>