Hamamatsu-Photonics K.k.

Akira Atsumi

Hiroyuki Kyushima

Hideki Shimoi

Yutaka Hasegawa

Koji Nagura

Eiichiro Kawano

Tomihiko Kuroyanagi

Masuya Mizuide

Masuo Ito

Tomoyuki Okada

A photomultiplier tube, a photomultiplier tube unit, and a performance-improved radiation detector for increasing a fixing area of a side tube in a faceplate while increasing an effective sensitive area of the faceplate. In the photomultiplier tube, a side face () of the faceplate () protrudes outward from an outer side wall () of a metal side tube (), so that a light receiving area for receiving light passing through a light receiving face () of the faceplate () is increased. The overhanging structure of the faceplate () is conceived based on a glass refractive index. The overhanging structure is aimed to receive light as much as possible which has not been received before. When the metal side tube () is fused to the glass faceplate (), a fusing method is adopted due to joint between glass and metal. Joint operation between the faceplate () and the side tube () is reliably ensured. Accordingly, the overhanging structure of the faceplate () is effective.

Photomultiplier tube, photomultiplier tube unit, and radiation detector

A metal side tube (), a glass faceplate (), and a stem plate () constitute a hermetically sealed vessel () for a photomultiplier tube. An edge portion () is provided at on open end (A) of the side tube (). The edge portion () is embedded in the faceplate () in such a manner as to strike on the faceplate (). Accordingly, high hermeticity at a joint between the side tube () and the faceplate () is ensured. The edge portion () extends upright in an axial direction of the side tube (), so that the edge portion () can be embedded as close to a side face () of the faceplate () as possible. This structure increases an effective sensitive area of the faceplate () to nearly 100%, and decreases dead area as close to 0 as possible. As described above, the photomultiplier tube () according to the present invention has enlarged effective sensitive area of the side tube () and enhanced hermeticity of the joint between the faceplate () and the side tube ().

Photomultiplier tube with enchanced hermiticity

A dynode constituting an electron multiplier or a photomultiplier may be provided with eight rows of channels each defined by an outer frame and a partitioning part of the dynode. In each channel, a plurality of electron multiplying holes may be arranged. In specified positions of the outer frame and the partitioning part of the dynode, glass receiving parts wider than the outer frame and the partitioning part may be provided integrally with the dynode. Glass parts may be bonded to all the glass receiving parts. The glass parts may be bonded by applying glass to the glass receiving parts and hardening the glass and each may have a generally dome-like convex shape. Each dynode may be formed after the dome-like glass part may be bonded to the glass receiving part.

Electron-multiplier and photo-multiplier having dynodes with partitioning parts

A dynode () constituting an electron multiplier or a photomultiplier is provided with eight rows of channels () each defined by an outer frame () and a partitioning part () of the dynode (). In each channel (), a plurality of electron multiplying holes () are arranged. In specified positions of the outer frame () and the partitioning part () of the dynode (), glass receiving parts () wider than the outer frame () and the partitioning part () are provided integrally with the dynode (). Glass parts () are bonded to all the glass receiving parts (). The glass parts () are bonded by applying glass to the glass receiving parts () and hardening the glass and each have a generally dome-like convex shape. Each dynode () is formed after the dome-like glass part () is bonded to the glass receiving part ().

A metal side tube (), a glass faceplate (), and a stem plate ( ) constitute a hermetically sealed vessel () for a photomultiplier tube. An edge portion () is provided at on open end (A) of the side tube (). The edge portion () is embedded in the faceplate () in such a manner as to strike on the faceplate (). Accordingly, high hermeticity at a joint between the side tube () and the faceplate () is ensured. The edge portion () extends upright in an axial direction of the side tube (), so that the edge portion () can be embedded as close to a side face () of the faceplate () as possible. This structure increases an effective sensitive area of the faceplate () to nearly 100%, and decreases dead area as close to 0 as possible. As described above, the photomultiplier tube () according to the present invention has enlarged effective sensitive area of the side tube () and enhanced hermeticity of the joint between the faceplate () and the side tube ().

Photomultiplier tube

A photomultiplier tube enhanced in simplicity and flexibility of mounting, a photomultiplier tube unit enhanced in photomultiplier tube assembling efficiency when unitized, and a radiation detector enhanced in assembling efficiency for a plurality of photomultiplier tubes. The photomultiplier tube () has a hermetically sealed vessel () easily screw-fixed in a predetermined position due to screwing means () provided in the stem plate (). As a result, the photomultiplier tube () can be very easily attached or detached so that even an unskilled person can mount the photomultiplier tube () easily and accurately in a predetermined position by screwing.

Photomultiplier tube, photomultiplier tube unit, radiation detector

A photomultiplier tube has a side tube with a stem plate fixed on one end and a faceplate fixed on the other. The side tube is formed of metal, and at least the portion of the stem plate contacting the metal side tube is formed of metal. The side tube and stem plate are fused together by laser welding or electron beam welding to form an airtight vessel, such that the outer edge of the stem plate does not protrude further externally than the outer surface of the side tube.

Photomultiplier tube and radiation detector

To reduce the size of a photomultiplier tube ( ), a side tube ( ) is fixedly secured by welding to a stem plate ( ) while an inner surface ( ) of the lower portion ( ) of the side tube ( ) is maintained to be in contact with an outer edge ( ) of the stem plate ( ). As a result, there is no projection like a flange at the lower portion of the photomultiplier tube ( ). Therefore, though it is difficult to perform resistance welding, the outside dimensions of the photomultiplier tube ( ) can be decreased, and the side tubes ( ) can densely abut to one another even if the photomultiplier tubes ( ) are arranged when applied. Hence, high-density arrangement of photomultiplier tubes ( ) are realized by assembling metallic stem plate ( ) and the side tube ( ) by, for example, laser welding.

A photomultiplier tube unit including photomultiplier tubes densely assembled and thereby having an improved light sensing efficiency. The outer surfaces ( b) of metal side tubes ( ) of photomultiplier tubes ( ) are in facial contact with one another, and thereby a high-density arrangement of photomultiplier tubes ( ) are achieved. The side tubes ( ) can be electrically connected to one another, and therefore the side tubes ( ) can be easily made equipotential. As a result, it is unnecessary to electrically connect the stem pin ( ) to the side tube ( ) of each photomultiplier tube ( ), facilitating the assembling of the photomultiplier tube unit. When a required photomultiplier tube ( ) in a device (e.g., a gamma camera) having thus-united multiple photomultiplier tubes is replaced with a new one, the troublesome work of replacing photomultiplier tubes one by one is obviated, simplifying the replacement work.

Photomultiplier tube tightly arranged with substantially no space between adjacent tubes

A photomultiplier of the present invention has an electron multiplier of a structure which can be manufactured easily. This electron multiplier is constituted by dynode plates that are stacked through insulators so as to be separated from each other at a predetermined interval. Each dynode plate comprises upper- and lower-electrode plates that are electrically connected to each other. The upper- and lower-electrode plates grip at least one of the insulators such that the gripped insulator is partly exposed.

Photomultiplier

A photomultiplier is constituted by a photocathode and an electron multiplier having a typical structure in which a dynode unit having a plurality of dynode plates stacked in an incident direction of photoelectrons, an anode plate, and an inverting dynode plate are sequentially stacked. Through holes for injecting a metal vapor are formed in the inverting dynode plate to form secondary electron emitting layers on the surfaces of dynodes supported by the dynode plates, and the photocathode. With this structure, the secondary electron emitting layers are uniformly formed on the surfaces of the dynodes. Therefore, variations in output signals obtained from anodes can be reduced regardless of the positions of the photocathode.

A photomultiplier includes a photocathode and an electron multiplier. A typical structure of the electron multiplier is obtained such that a dynode unit constituted by stacking a plurality of dynode plates in the incident direction of photoelectrons, an anode plate, and an inverting dynode plate are stacked. The anode plate has electron through holes at a predetermined portion to cause secondary electrons emitted from the dynode unit to pass therethrough. Each electron through hole has a diameter on the inverting dynode plate side larger than that on the dynode unit side, thereby increasing the capture area of the secondary electrons orbit-inverted by the inverting dynode plate.

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Hamamatsu, Japan

Akira Atsumi