EP0876678A1 - Photomultiplicateur - Google Patents

Photomultiplicateur

Info

Publication number
EP0876678A1
EP0876678A1 EP96901061A EP96901061A EP0876678A1 EP 0876678 A1 EP0876678 A1 EP 0876678A1 EP 96901061 A EP96901061 A EP 96901061A EP 96901061 A EP96901061 A EP 96901061A EP 0876678 A1 EP0876678 A1 EP 0876678A1
Authority
EP
European Patent Office
Prior art keywords
layer
photocathode
layers
electron multiplying
anode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP96901061A
Other languages
German (de)
English (en)
Inventor
Duncan James Westland
Vladimir Skarda
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ERA Patents Ltd
Original Assignee
ERA Patents Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ERA Patents Ltd filed Critical ERA Patents Ltd
Publication of EP0876678A1 publication Critical patent/EP0876678A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
    • H01J43/04—Electron multipliers

Definitions

  • the present invention relates to a photomultiplier device.
  • a photocathode which usually includes a photosensitive alkali metal, which emits photoelectrons in response to the incident photons.
  • the photoelectrons strike a first dynode, which emits secondary electrons, thereby multiplying the original photoelectrons.
  • the emitted electrons impinge on subsequent downstream dynodes, each emitting secondary electrons, thereby further multiplying the electrons.
  • the potential difference between adjacent dynodes is typically 100 V, and this multiplies the electrons by a factor of around 10 for each dynode.
  • the electrons emitted from the array of dynodes are detected by an anode, which gives an output which is a function of the intensity of the radiation incident upon the photocathode.
  • All of the components are provided in a vacuum envelope, normally made of metal, ceramic or glass, which includes a transparent face through which photons pass to the photocathode.
  • the material from which the photocathode is made depends on the radiation which is to be detected, for example whether the photomultiplier is to detect visible light, infra-red, ultra-violet, X-ray or gamma-ray radiation.
  • Typical photo ultipliers have a gain of about l million, although this can be increased by the provision of additional dynodes.
  • the problem with conventional photomultiplier tubes is their large size. Accordingly photodiodes and other solid state detectors have been increasingly used. These devices have the advantage of being smaller, less expensive, and do not need as high a voltage as photomultiplier tubes, however they are not as sensitive as photomultiplier tubes unless they are cooled to cryogenic temperatures.
  • a photomultiplier device comprises a plurality of layers bonded together, the layers including a photocathode layer for emitting photoelectrons when a photon is incident upon it, an electron multiplying layer for multiplying the electrons emitted from the photocathode, and an anode layer upon which the electrons emitted from the electron multiplying layer are incident.
  • the photomultiplier device By forming the photomultiplier device from a plurality of layers bonded together, rather than from discrete components provided in a vacuum envelope as with conventional devices, the device can be miniaturized. Further, microengineering techniques can be used in the manufacture of the device, making production costs similar to those for other solid state devices.
  • the photocathode layer, the electron multiplying layer and the anode layer are separated from each other by spacer members, and that the cavity between the layers is evacuated. This gives improved transmission of electrons between the layers.
  • the photocathode layer is preferably formed by coating a photoresponsive layer on a transparent substrate layer.
  • the transparent substrate layer forms a window through which photons pass to the photocathode.
  • the coating may be etched to remove selectively the photoresponsive material and allow bonding of spacers or the electron multiplying layer to the substrate layer.
  • the photocathode may be coated directly onto the electron multiplying layer.
  • the electron multiplying layer is advantageously a microchannel plate. This has the advantage of being thin and flat compared to an array of dynodes. A plurality of electron multiplying layers may be provided in series to increase the amplification of electrons.
  • the photocathode layer, the electron multiplying layer and the anode layer are each formed on or from a wafer which, when bonded together, may be diced to form a plurality of discrete devices.
  • anode layer is advantageous for the anode layer to be a resistive anode or a segmented anode. This allows the photomultiplier to give positional information relative to the incident radiation.
  • a method of manufacturing a photomultiplier device comprises forming a photocathode layer for emitting photoelectrons when a photon is incident upon it, an electron multiplying layer for multiplying electrons emitted by the photocathode layer, and an anode layer, and bonding the plurality of layers together.
  • the photocathode layer is formed by coating a photoresponsive material on a transparent substrate, the photocathode layer subsequently being bonded to one face of the electron multiplying layer.
  • the photocathode layer may be bonded to a spacer which is in turn bonded to the electron multiplying layer, and the electron multiplying layer may be bonded to a further spacer which is in turn bonded to the anode layer.
  • the transparent substrate, the electron multiplying layer, and the anode layer are in the form of wafers, in which case the method may include the additional step of dicing the wafers after bonding to form a plurality of discrete devices.
  • Figure 1 shows a first example
  • Figure 2 shows a second example
  • Figure 3 shows a third example
  • Figure 4 shows a resistive anode for use in any of the examples.
  • Figure 1 shows a first example of a photomultiplier device according to the present invention.
  • a transparent substrate 1 of glass, quartz or sapphire is provided, and is etched to form a number of window recesses.
  • the recesses are formed by a dissolution in a liquid or flux of energetic or reactive atoms, or ions.
  • a photoresponsive material 2 is then coated in each window recess.
  • the photocathode material 2 may be, for example gallium arsenide, indium phosphide, or other mixture of alkali metals and their compounds which emit electrons when radiation is incident upon them.
  • the photocathode material 2 may be selectively etched to allow for bonding of spacer members 3 to the transparent substrate 1.
  • the spacer members 3 are bonded using any suitable bonding method, for example by adhesive, fusion, solder or anodic bonding.
  • a microchannel plate 4 is bonded to the spacer members 3 by a suitable bonding method in spaced apart, confronting relation to the photocathode 2.
  • the microchannel plate is conventional in construction and comprises an array of channels, each having a diameter of around lO ⁇ m. Each channel has a semiconductor photosensitive inner surface. An electric field is applied along the length of each channel. When a photon is incident on the semiconductor surface, secondary electrons are emitted. These secondary electrons impinge on the semiconductor surface, causing further secondary electrons to be emitted, causing multiplication of the photoelectron.
  • Appropriate microchannel devices are available commercially from Hamamatsu Photonics KK (Shizuoka-Ken, Japan) and others.
  • the channels of the microchannel plate may be provided at an angle with respect to the face of the plate. This prevents positive ions from residual gases in the photomultiplier from being accelerated along the channels, and causing stray electron emissions.
  • Spacer members 5 are bonded to the face of the microchannel plate 4 opposite the photocathode 2, and an anode layer 6 is bonded onto these spacers 5.
  • the volumes between the photocathode 2 and the microchannel plate 4, and between the microchannel plate 4 and the anode 6 are evacuated.
  • the bonded layers are cut, or diced, perpendicular to the layers to divide the layers into a plurality of discrete devices.
  • photons are transmitted through the window 1, and onto the photocathode layer 2.
  • the photocathode layer 2 emits photoelectrons in response to the photons incident upon it, and these are transmitted to the microchannel plate 4.
  • the microchannel plate multiplies the photoelectrons striking it, and transmits electrons towards the anode layer 6, where they are detected.
  • the photocathode 2 , microchannel plate 4 and anode layer 6 are all biased with a voltage to ensure the electrons generated are accelerated towards the anode layer 6.
  • Figure 2 shows a second example of the present invention.
  • the photocathode layer 2 is bonded directly onto one face of the microchannel plate 4, and the anode layer 6 is bonded directly onto the opposite face of the microchannel plate 4.
  • the transparent substrate 1 is not etched to form recessed before the formation of the photocathode layer 2.
  • the transparent substrate 1 can be omitted, providing the device is to be used in a vacuum.
  • a plurality of microchannel plates may be bonded together in series. Such a device is shown in Figure 3.
  • a segmented anode may be provided.
  • the voltage of each segment can be monitored to identify the position.
  • a resistive anode 10 can be used.
  • Such an anode 10 is a resistive sheet connected to a positive supply via resistors R, at various locations on the anode 10.
  • resistors R resistors
  • position detection may be achieved by providing an array of detectors.
  • the array may be a one or two dimensional array.

Landscapes

  • Electron Tubes For Measurement (AREA)

Abstract

La présente invention concerne un photomultiplicateur constitué par un certain nombre de couches (2, 4, 6) liées les unes aux autres. Il s'agit d'une couche photocathodique (2) qui émet des photoélectrons quand elle reçoit un photon, d'une couche (4) multiplicatrice des électrons qu'émet la photocathode (2) et d'une couche anodique (6) qui reçoit les électrons émis par la couche multiplicatrice (4). Les différentes couches (2, 4, 6) peuvent être espacées par des éléments d'écartement (3, 5) et la cavité comprise entre elles peut être mise sous vide. La couche photocathodique (2) peut être formée à partir d'un revêtement photosensible sur un support transparent (1). La couche multiplicatrice d'électrons (4) peut être une plaque à microcanaux. Les différentes couches (2, 4, 6) peuvent avoir la forme de plaquettes. Dans ce cas, la fabrication de l'appareil comprend une opération de découpage en dés des plaquettes après que les couches ont été liées entre elles, pour former de nombreux composants distincts.
EP96901061A 1996-01-25 1996-01-25 Photomultiplicateur Withdrawn EP0876678A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/GB1996/000178 WO1997027615A1 (fr) 1996-01-25 1996-01-25 Photomultiplicateur

Publications (1)

Publication Number Publication Date
EP0876678A1 true EP0876678A1 (fr) 1998-11-11

Family

ID=10786639

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96901061A Withdrawn EP0876678A1 (fr) 1996-01-25 1996-01-25 Photomultiplicateur

Country Status (3)

Country Link
EP (1) EP0876678A1 (fr)
GB (1) GB9815891D0 (fr)
WO (1) WO1997027615A1 (fr)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3408532A (en) * 1965-12-06 1968-10-29 Northrop Corp Electron beam scanning device
FR2676862B1 (fr) * 1991-05-21 1997-01-03 Commissariat Energie Atomique Structure multiplicatrice d'electrons en ceramique notamment pour photomultiplicateur et son procede de fabrication.
US5264693A (en) * 1992-07-01 1993-11-23 The United States Of America As Represented By The Secretary Of The Navy Microelectronic photomultiplier device with integrated circuitry
FI940740A0 (fi) * 1994-02-17 1994-02-17 Arto Salokatve Detektor foer paovisning av fotoner eller partiklar, foerfarande foer framstaellning av detektorn och maetningsfoerfarande

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9727615A1 *

Also Published As

Publication number Publication date
WO1997027615A1 (fr) 1997-07-31
GB9815891D0 (en) 1998-09-16

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