Hamamatsu-photonics K.k.

Kuniyoshi Mori

Toru Hirohata

Minoru Niigaki

Hirofumi Kan

Satoshi Suzuki

Daichi Masuko

Tomoko Mochizuki

Shinichi Yamashita

Yoshinori Inagaki

Tsuneo Ihara

Rina Konno

Toshiharu Ai

Yoshiyuki Natsume

Akihiko Ohtomo

Taisuke Nakaya

Provided is a photomultiplier tube including: a container including a window portion formed of a light-transmitting material, and a tubular portion that is connected to the window portion and defines a vacuum space in combination with the window portion; a photoelectric surface that is formed of a photoelectron-emitting material consisting of sodium, potassium, and antimony, is provided on a first surface of the window portion on a side of the vacuum space, and emits photoelectrons in correspondence with incident light; and an electron multiplier that emits secondary electrons in correspondence with incidence of the photoelectrons emitted from the photoelectric surface, and multiplies the secondary electrons. An aluminum oxide layer is formed between the photoelectric surface and the window portion and on a surface of the tubular portion.

Photomultiplier tube including a protective layer

A streak tubeA comprises an envelopeincluding an entrance faceplate; a photocathodefor converting light received from the entrance faceplateinto an electron; an anodehaving an openingfor passing there through the electron emitted from the photocathode; deflecting electrodesfor controlling a deflection of the electron having passed through the openingof the anode; and a fluorescent screenfor detecting a streak image due to the electron having the deflection controlled by the deflecting electrodes. The photocathodeis configured so as to be kept from directly facing the anodeon an axis of an electric field formed between the entrance faceplateand the anodeor on a tube axis passing the center of the openingin the anodewithin the envelope. Thus, the streak tube capable of suppressing influences of noise signals on signals corresponding to incident light can be realized.

Streak tube including control electrode having blocking portion between a photocathode and an anode

Provided are a photocathode plate capable of stably achieving a high sensitive property, and an electron tube using such a photocathode plate. In a photomultiplier tube, an insulating layeris formed between a semiconductor electron emission layerin a photocathode plateA, and a first electrodeelectrically connected to an electron releasing portion. This insulating layerpermits the photocathode plateA to be cleaned by heat cleaning at a high temperature, in a stage before formation of an active layeron an exposed region of the semiconductor electron emission layerin the electron releasing portion. This makes it feasible to effectively clean the exposed region of the semiconductor electron emission layerin the electron releasing portionand to stabilize the physical properties of the exposed region. In consequence, a higher sensitive property can be stably achieved in the photocathode plateA and in the photomultiplier tubeusing the photocathode plateA.

Photocathode plate and electron tube

In the case of a thick light-absorbing layer, a phenomenon of a decrease in the time resolution occurs. However, when the thickness of the light-absorbing layeris limited, a portion of low electron concentration in one electron group is cut out, and hence overlap regions of adjacent electron concentration distributions decrease. Therefore, by shortening the transit time necessary for the passage of electrons, regions of overlapping electron distributions due to diffusion can also be suppressed. Furthermore, the strength of an electric field within a light-absorbing layer can be increased by thinning the light-absorbing layer. Therefore, the time resolution of infrared rays can be remarkably improved by a synergistic action of these effects. If it is assumed that the time resolution is 40 ps (picoseconds), for example, when the thickness of a light-absorbing layer is 1.3 &#x3bc;m which is nearly equal to the wavelength of infrared, then a possible time resolution is 7.5 ps when this thickness is 0.19 &#x3bc;m.

Semiconductor photocathode

A photocathode and an electron tube in which the photocathode plate can be securely fixed without using any adhesive. Even under the severe condition that a high vibration resistance is required or thermal stress occurs because of great temperature variation, it can be used widely for an image intensifier, a streak tube, or a photomultiplier. The photocathode plate of the photocathode is sandwiched between a faceplate and a support plate. First pins embedded in the faceplate are joined to the support plate. Therefore, the photocathode plate can be readily fixed securely to the faceplate without using any adhesive.

Photocathode and electron tube

A voltage control section for controlling a pulsed acceleration voltage applied between a photoelectron releasing layer and an X-ray target in order to accelerate a photoelectron is further provided, so that the acceleration voltage is maintained at a pulse top voltage until the X-ray target is bombarded with the photoelectron after the photoelectron is released from the photoelectron releasing layer. The pulse width of acceleration voltage can be set narrower to such an extent that no discharge occurs, which enables the pulse top voltage to become higher, whereby the energy of pulse X-rays can be made higher by enhancing the speed of photoelectrons.

X-ray generator

An imaging tube having a fiber optic plate (FOP) as an output faceplate. On one surface of the FOP within an evacuated envelope is deposited a first transparent conductive layer. On the first transparent conductive layer is deposited a fluorescent layer. On the fluorescent layer is deposited a metal-back electrode. On the other surface of the FOP outside the evacuated envelope is deposited a second transparent conductive layer. The first transparent conductive layer and the metal-back electrode are electrically connected so that an electrical field is not developed across the fluorescent layer when the metal-back electrode is applied with a high positive voltage and the second transparent conductive layer is grounded. Therefore, even if leakage currents flow through the FOP, electric charges impinging upon the first transparent conductive layer will not cause the fluorescent layer to generate noise spots.

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Hamamatsu, Japan

Kuniyoshi Mori