EP0423886A1 - Multi-path photomultiplier with high inter-signal resolution - Google Patents

Multi-path photomultiplier with high inter-signal resolution Download PDF

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Publication number
EP0423886A1
EP0423886A1 EP90202717A EP90202717A EP0423886A1 EP 0423886 A1 EP0423886 A1 EP 0423886A1 EP 90202717 A EP90202717 A EP 90202717A EP 90202717 A EP90202717 A EP 90202717A EP 0423886 A1 EP0423886 A1 EP 0423886A1
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EP
European Patent Office
Prior art keywords
holes
electrode
dynode
emitting
photomultiplier tube
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Withdrawn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
EP90202717A
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German (de)
French (fr)
Inventor
Jean-Pierre Société Civile S.P.I.D. Boutot
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.)
Photonis SAS
Koninklijke Philips NV
Original Assignee
Photonis SAS
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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Application filed by Photonis SAS, Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Photonis SAS
Publication of EP0423886A1 publication Critical patent/EP0423886A1/en
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
    • H01J43/04—Electron multipliers
    • H01J43/06—Electrode arrangements
    • H01J43/18—Electrode arrangements using essentially more than one dynode
    • H01J43/22—Dynodes consisting of electron-permeable material, e.g. foil, grid, tube, venetian blind
    • 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 tube with N parallel paths, comprising an input window and an electron multiplier of the "hole plate” type, partitioned into N elementary multipliers, and the first stage of which comprises an input electrode and a first emitting electrode.
  • the invention finds a particularly advantageous application in the field of nuclear physics and, more particularly, in the detection and precise localization of elementary particles.
  • European patent No. 0 131 339 discloses a photomultiplier tube conforming to the preamble, the first emitting electrode of which is a first emitting half-dynode, and the upper stages of which, beyond the first stage, consist of dynodes formed by two half dynodes appearing, like the first emitting half-dynode, as conductive plates pierced with holes; the first half-dynode is an extracting half-dynode, while the second half-dynode, provided with secondary emission, is the transmitting half-dynode.
  • the two half-dynodes of the same dynode are designed to be brought to substantially the same electrical potential and, in operation, one of the roles played by the extracting half-dynode is to attract towards the emitting half-dynode, by passing them through its own holes, the secondary electrons produced on the walls of the holes of the preceding emitting half-dynode, itself brought to a lower electrical potential.
  • the extracting half-dynode and the preceding transmitting half-dynode with which it is associated are placed at a short distance from each other and have the same structure in the sense that their respective holes correspond.
  • the extractor half-dynode is not, a plate with holes like the other half-dynodes of the multiplier, but is an input electrode constituted by a simple or double grid of high transparency with respect to photoelectrons, emitted by the photocathode deposited on the input window, and that said input electrode is responsible for attracting, for secondary multiplication, the first emitting half-dynode.
  • each extracting half-dynode also serves to electrically shield the emitting half-dynode of the same pair so that the electric field in the space between these two half-dynodes is weak, with the near field created by the following extracting half-dynode associated with said transmitting half-dynode.
  • the secondary electrons produced by the emitting half-dynode would be subjected as of their exit to an excessive electric field which would make them immediately fall back at the same place where they were created.
  • the hole plate electron multiplier is placed in the vicinity immediately from the photocathode. In this way, any photon reaching a given elementary photocathode produces photoelectrons which will all be collected by the corresponding elementary multiplier.
  • the technical problem to be solved by the object of the present invention is to produce a photomultiplier tube conforming to the preamble which would not exhibit crosstalk at the level of the first stage, while maintaining the essential proximity focusing of the tube known from the 'state of the art.
  • the solution to the technical problem posed consists, according to the present invention, in that the walls of the holes of the first emitting electrode are covered with a photoemissive material.
  • the invention amounts to carrying out the transduction of incident photons into photoelectrons not on a photocathode deposited in a conventional manner on the entry window of the photomultiplier tube, but on the holes of the first emitting electrode itself whose function, instead of multiplying incident electrons, is then to produce photoelectrons whose particularity is to have all a low initial speed which does not allow them to cross the first emitting electrode by another hole than where they were created.
  • the characteristic technical effect resulting from the invention is therefore to avoid the phenomenon of "elastic rebound" observed in the known tube described above, and, consequently, not to cause crosstalk on the first stage of the electron multiplier. , in accordance with the objective assigned with regard to the technical problem posed.
  • the input electrode associated with the first emitting electrode no longer plays the role of extraction of the photoelectrons, as in the known tube, since these are produced downstream and no longer in upstream of said input electrode. By cons, it still retains its role of shielding the first emitting electrode, become photocathode in accordance with the provisions of the present invention.
  • the input electrode In order to obtain maximum sensitivity, the input electrode must offer the greatest optical transparency.
  • said input electrode may be in the form of a conductive grid similar to that already used in the prior art, but for which the required transparency was exercised in an equivalent manner with respect to the incident photoelectrons.
  • the optical transmission of the input stage of the tube can then be further improved when, according to the invention, the input electrode is a conductive grid made up of wires arranged opposite the holes of the first emitting electrode and reflecting the incident light towards the walls of said holes.
  • the input electrode is made of a thin layer of a conductive material deposited on the input window. This particular embodiment has the advantage of being easy and inexpensive to implement.
  • the transduction efficiency of the photocathode of the photomultiplier tube according to the invention can be further increased if the walls of the holes of the first emitting electrode include a layer of reflective material on which said photoemissive material is deposited. In this way, the path of the incident light through the photoemissive material is elongated by reflection, which tends to increase the probability of transformation of photons into photoelectrons.
  • FIG. 1 represents, in section, a photomultiplier tube with N parallel channels, N being able to reach 64 for example.
  • This tube has an entry window 10, made of glass or quartz, and an electron multiplier 20 of the "hole plate” type, partitioned into N elementary multipliers 20a.
  • the first stage of the electron multiplier 20 comprises an input electrode 30 and a first emitting electrode 40.
  • dynodes made up of two half-dynodes in the form of plates with holes, of which l one, such as D′2 or D′3, is the extracting half-dynode, and the other, like D2 or D3, is the emitting half-dynode which, endowed with secondary emission, has the role of multiplying the incident electrons on the walls of its holes.
  • the two half-dynodes of the same dynode are brought to the same electrical potential, while each dynode is brought to an electrical potential greater than that of the preceding dynode.
  • the emitting half-dynodes 40, D2, D3, ... are separated from the following extracting half-dynodes D′2, D′3, ..., by insulating spacers 60, like small balls of resin for example.
  • the N elementary multipliers 20a lead to N adjacent anodes 60a and are separated from each other by partitions 21a which are electron-tight, produced by masking and photoengraving.
  • the walls 41 of the holes 42 of said first emitting electrode 40 are covered with a photoemissive material 43.
  • said photoemissive material can be an alkaline antimonide composed of antimony and one or more alkalines from potassium, sodium and cesium.
  • the first emitting electrode 40 then plays the role of photocathode which transforms incident photons 70 into photoelectrons 71 whose initial speed is not sufficient to pass from one hole to another, and which, consequently, cannot cause crosstalk between the tracks.
  • the input electrode 30 is made of a thin layer of conductive material deposited on the input window 30.
  • This input electrode ensures good optical transparency with respect to incident photons 70 and, on the other hand, being brought to an electrical potential equal to or slightly lower than that of the first emitting electrode 40, it ensures the shielding of said first emitting electrode so as to avoid the return of the photoelectrons 71 on the walls 41 of the holes 42.
  • FIG. 2 shows another embodiment of the invention in which the walls 41 of the holes 42 of the first emitting electrode 40 comprise a layer 44 of a reflective material on which said photoemissive material 43 is deposited.
  • the reflective layer 44 can be, for example, made up of aluminum.
  • the input electrode 30 is a conductive grid made up of wires 31 arranged opposite the holes 42 of the first emitting electrode 40, said wires 31 have a shape such that 'They reflect the incident light 70 on the walls 41 of said holes.
  • the optical transparency of the grid 30 is then increased, as well as the efficiency of the photomultiplier tube according to the invention.

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  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)
  • Electroluminescent Light Sources (AREA)
  • Common Detailed Techniques For Electron Tubes Or Discharge Tubes (AREA)

Abstract

Photomultiplier tube with N parallel paths, containing an entrance window (10) and an electron multiplier (20) of the "perforated plate" type, partitioned into N elementary multipliers (20a), and the first stage of which comprises an entrance electrode (30) and a first emitter electrode (40). According to the invention, the walls (41) of the holes (42) of the said first emitter electrode (40) are covered with a photoemissive material (43). Application to the detection of elementary particles in nuclear physics. <IMAGE>

Description

La présente invention concerne un tube photomulti­plicateur à N voies parallèles, comportant une fenêtre d'en­trée et un multiplicateur d'électrons du type "à plaques à trous", cloisonné en N multiplicateurs élémentaires, et dont le premier étage comprend une électrode d'entrée et une pre­mière électrode émettrice.The present invention relates to a photomultiplier tube with N parallel paths, comprising an input window and an electron multiplier of the "hole plate" type, partitioned into N elementary multipliers, and the first stage of which comprises an input electrode and a first emitting electrode.

L'invention trouve une application particulièrement avantageuse dans le domaine de la physique nucléaire et, plus spécialement, dans la détection et la localisation précise des particules élémentaires.The invention finds a particularly advantageous application in the field of nuclear physics and, more particularly, in the detection and precise localization of elementary particles.

On connaît du brevet européen n° 0 131 339 un tube photomultiplicateur conforme au préambule dont la première électrode émettrice est une première demi-dynode émettrice, et dont les étages supérieurs, au-delà du premier étage, sont constitués de dynodes formées de deux demi-dynodes se présen­tant, de même que la première demi-dynode émettrice, comme des plaques conductrices percées de trous; la première demi-dynode est une demi-dynode extractrice, tandis que la deuxième demi-­dynode, pourvued'émission secondaire, est la demi-dynode émettrice. Les deux demi-dynodes d'une même dynode sont pré­vues pour être portées sensiblement au même potentiel électri­que et, en fonctionnement, un des rôles joué par la demi-dyno­de extractrice est d'attirer vers la demi-dynode émettrice, en les faisant passer à travers ses propres trous, les électrons secondaires produits sur les parois des trous de la demi-dynode émettrice précédente, elle-même portée à un poten­tiel électrique plus faible. Généralement, la demi-dynode ex­tractrice et la demi-dynode émettrice précédente à laquelle elle est associée sont placées à faible distance l'une de l'autre et présentent la même structure en ce sens que leurs trous respectifs se correspondent. Dans le cas particulier du premier étage, la demi-dynode extractrice n'est pas, une plaque à trous comme les autres demi-dynodes du multiplicateur, mais est une électrode d'entrée constituée par une grille simple ou double de forte transparence vis à vis des photoélectrons, émis par la photocathode déposée sur la fenêtre d'entrée, et que ladite électrode d'entrée est chargée d'attirer, pour multiplication secondaire, sur la première demi-dynode émettrice.European patent No. 0 131 339 discloses a photomultiplier tube conforming to the preamble, the first emitting electrode of which is a first emitting half-dynode, and the upper stages of which, beyond the first stage, consist of dynodes formed by two half dynodes appearing, like the first emitting half-dynode, as conductive plates pierced with holes; the first half-dynode is an extracting half-dynode, while the second half-dynode, provided with secondary emission, is the transmitting half-dynode. The two half-dynodes of the same dynode are designed to be brought to substantially the same electrical potential and, in operation, one of the roles played by the extracting half-dynode is to attract towards the emitting half-dynode, by passing them through its own holes, the secondary electrons produced on the walls of the holes of the preceding emitting half-dynode, itself brought to a lower electrical potential. Generally, the extracting half-dynode and the preceding transmitting half-dynode with which it is associated are placed at a short distance from each other and have the same structure in the sense that their respective holes correspond. In the particular case of first stage, the extractor half-dynode is not, a plate with holes like the other half-dynodes of the multiplier, but is an input electrode constituted by a simple or double grid of high transparency with respect to photoelectrons, emitted by the photocathode deposited on the input window, and that said input electrode is responsible for attracting, for secondary multiplication, the first emitting half-dynode.

Par ailleurs, chaque demi-dynode extractrice, ainsi que l'électrode d'entrée, sert également à blinder électri­quement la demi-dynode émettrice de la même paire de façon que le champ électrique dans l'espace compris entre ces deux demi-dynodes soit faible, au champ près créé par la demi-dynode extractrice suivante associée à ladite demi-dynode émettrice. En effet, en l'absence de blindage, les électrons secondaires produits par la demi-dynode émettrice seraient soumis dès leur sortie à un champ électrique trop important qui les ferait aussitôt retomber à l'endroit même où ils ont été créés.Furthermore, each extracting half-dynode, as well as the input electrode, also serves to electrically shield the emitting half-dynode of the same pair so that the electric field in the space between these two half-dynodes is weak, with the near field created by the following extracting half-dynode associated with said transmitting half-dynode. Indeed, in the absence of shielding, the secondary electrons produced by the emitting half-dynode would be subjected as of their exit to an excessive electric field which would make them immediately fall back at the same place where they were created.

Le tube photomultiplicateur connu de l'état de la technique est utilisé en physique nucléaire pour la détection précise des particules élémentaires. A cet effet et dans le but d'augmenter la résolution spatiale de l'observation, ce tube est cloisonné de manière à réaliser N (N=4,9,16,...) tubes photomultiplicateurs élémentaires dans l'enveloppe d'un seul tube. C'est pourquoi le multiplicateur d'électrons lui-même est divisé par des cloisons étanches aux électrons en N multiplicateurs élémentaires qui débouchent sur N anodes contigües situées à proximité et en regard de la sortie des multiplicateurs élémentaires respectifs.The photomultiplier tube known from the state of the art is used in nuclear physics for the precise detection of elementary particles. To this end and with the aim of increasing the spatial resolution of the observation, this tube is partitioned so as to produce N (N = 4,9,16, ...) elementary photomultiplier tubes in the envelope of a single tube. This is why the electron multiplier itself is divided by electron-tight partitions into N elementary multipliers which lead to N contiguous anodes located near and opposite the output of the respective elementary multipliers.

Afin de définir, sur la photocathode déposée sur la fenêtre d'entrée du tube, N photocathodes élémentaires corres­pondant aux N voies de multiplication et d'éviter toute dia­photie entre lesdites photocathodes élémentaires, le multipli­cateur d'électrons à plaques à trous est placé au voisinage immédiat de la photocathode. De cette manière, tout photon atteignant une photocathode élémentaire donnée produit des photoélectrons qui seront tous collectés par le multiplicateur élémentaire correspondant.In order to define, on the photocathode deposited on the entry window of the tube, N elementary photocathodes corresponding to the N multiplication paths and to avoid any crosstalk between said elementary photocathodes, the hole plate electron multiplier is placed in the vicinity immediately from the photocathode. In this way, any photon reaching a given elementary photocathode produces photoelectrons which will all be collected by the corresponding elementary multiplier.

Toutefois, malgré les précautions prises, il s'avè­re expérimentalement que le tube photomultiplicateur cloisonné connu présente néanmoins une certaine diaphotie entre voies. L'explication de ce phénomène parasite se trouve dans la ré­partition statistique des vitesses initiales des électrons se­condaires produits par les demi-dynodes émettrices. Il appa­raît que la plupart des électrons secondaires ont, certes, une vitesse initiale suffisamment faible pour que, sous l'effet du champ extracteur, ils traversent la demi-dynode émettrice par l'ouverture de sortie même du trou sur la paroi duquel ils ont pris naissance. Ces électrons secondaires ne donnent pas lieu à diaphotie. Cependant, on constate qu'un certain nombre d'é­lectrons secondaires acquièrent une vitesse initiale suffisam­ment élevée pouvant être égale à celle des électrons inci­dents, ce sont les électrons rétrodiffusés et élastiques qui peuvent parcourir des distances équivalentes à plusieurs trous. Dans les étages supérieurs du multiplicateur, ces élec­trons sont arrêtés par les cloisons étanches, mais dans le premier étage, dépourvu de cloisonnement, les électrons rétro­diffusés élastiquement, produits par la première demi-dynode émettrice sont susceptibles de passer d'une voie à une autre et de provoquer ainsi la diaphotie observée.However, despite the precautions taken, it turns out experimentally that the known partitioned photomultiplier tube nevertheless exhibits a certain crosstalk between paths. The explanation of this parasitic phenomenon is found in the statistical distribution of the initial velocities of the secondary electrons produced by the emitting half-dynodes. It appears that most of the secondary electrons have, of course, an initial speed sufficiently low that, under the effect of the extractor field, they cross the emitting half-dynode by the very exit opening of the hole on the wall of which they took birth. These secondary electrons do not give rise to crosstalk. However, it is noted that a certain number of secondary electrons acquire a sufficiently high initial speed which can be equal to that of the incident electrons, it is the backscattered and elastic electrons which can travel distances equivalent to several holes. In the upper stages of the multiplier, these electrons are stopped by the bulkheads, but in the first stage, devoid of partitioning, the electrons backscattered elastically, produced by the first emitting half-dynode are likely to pass from one channel to another and thus cause the observed crosstalk.

Aussi, le problème technique à résoudre par l'objet de la présente invention est de réaliser un tube photomulti­plicateur conforme au préambule qui ne présenterait pas de diaphotie au niveau au premier étage, tout en maintenant l'in­dispensable focalisation de proximité du tube connu de l'état de la technique.Also, the technical problem to be solved by the object of the present invention is to produce a photomultiplier tube conforming to the preamble which would not exhibit crosstalk at the level of the first stage, while maintaining the essential proximity focusing of the tube known from the 'state of the art.

La solution au problème technique posé consiste, selon la présente invention, en ce que les parois des trous de la première électrode émettrice sont recouvertes d'un matériau photoémissif. Ainsi, l'invention revient à réaliser la trans­duction des photons incidents en photoélectrons non pas sur une photocathode déposée de façon classique sur la fenêtre d'entrée du tube photomultiplicateur, mais sur les trous de la première électrode émettrice elle-même dont la fonction, au lieu de multiplier des électrons incidents, est alors de pro­duire des photoélectrons dont la particularité est d'avoir tous une faible vitesse initiale qui ne leur permet pas de traverser la première électrode émettrice par un autre trou que celui où ils ont été créés. L'effet technique caractéris­tique résultant de l'invention est donc d'éviter le phénomène de "rebond élastique" observé dans le tube connu précédemment décrit, et, par conséquent, de ne pas provoquer de diaphotie sur le premier étage du multiplicateur d'électrons, conformé­ment à l'objectif assigné en regard du problème technique po­se.The solution to the technical problem posed consists, according to the present invention, in that the walls of the holes of the first emitting electrode are covered with a photoemissive material. Thus, the invention amounts to carrying out the transduction of incident photons into photoelectrons not on a photocathode deposited in a conventional manner on the entry window of the photomultiplier tube, but on the holes of the first emitting electrode itself whose function, instead of multiplying incident electrons, is then to produce photoelectrons whose particularity is to have all a low initial speed which does not allow them to cross the first emitting electrode by another hole than where they were created. The characteristic technical effect resulting from the invention is therefore to avoid the phenomenon of "elastic rebound" observed in the known tube described above, and, consequently, not to cause crosstalk on the first stage of the electron multiplier. , in accordance with the objective assigned with regard to the technical problem posed.

Dans le tube photomultiplicateur selon l'invention, l'électrode d'entrée associée à la première électrode émettri­ce ne joue plus le rôle d'extraction des photoélectrons, comme dans le tube connu, puisque ceux-ci sont produits en aval et non plus en amont de ladite électrode d'entrée. Par contre, celle-ci conserve toujours son rôle de blindage de la première électrode émettrice, devenue photocathode conformément aux dispositions de la présente invention.In the photomultiplier tube according to the invention, the input electrode associated with the first emitting electrode no longer plays the role of extraction of the photoelectrons, as in the known tube, since these are produced downstream and no longer in upstream of said input electrode. By cons, it still retains its role of shielding the first emitting electrode, become photocathode in accordance with the provisions of the present invention.

De façon à obtenir une sensibilité maximale, l'électrode d'entrée doit offrir la transparence optique la plus grande. Dans ce but, ladite électrode d'entrée peut se présenter sous la forme d'une grille conductrice analogue à celle déjà utilisée dans l'état de la technique, mais pour la­quelle la transparence exigée s'exerçait de manière équivalen­te à l'égard des photoélectrons incidents. La transmission op­tique de l'étage d'entrée du tube peut alors être encore amé­liorée lorsque, selon l'invention, l'électrode d'entrée est une grille conductrice constituée de fils disposés en regard des trous de la première électrode émettrice et réfléchissant la lumière incidente vers les parois desdits trous. Ainsi, la lumière qui serait perdue par réflexion arrière sur les fils de la grille est récupérée par effet de miroir en direction des trous photoémissifs de la première électrode émettrice. Un autre moyen d'obtenir une transparence optique satisfaisante consiste, selon l'invention, en ce que l'électrode d'entrée est réalisée en une couche mince d'un matériau conducteur dé­posée sur la fenêtre d'entrée. Ce mode de réalisation particu­lier a l'avantage d'être de mise en oeuvre aisée et peu oné­reuse.In order to obtain maximum sensitivity, the input electrode must offer the greatest optical transparency. For this purpose, said input electrode may be in the form of a conductive grid similar to that already used in the prior art, but for which the required transparency was exercised in an equivalent manner with respect to the incident photoelectrons. The optical transmission of the input stage of the tube can then be further improved when, according to the invention, the input electrode is a conductive grid made up of wires arranged opposite the holes of the first emitting electrode and reflecting the incident light towards the walls of said holes. Thus, the light which would be lost by rear reflection on the wires of the grid is recovered by the mirror effect in the direction of the photoemissive holes of the first emitting electrode. Another way to get satisfactory optical transparency consists, according to the invention, in that the input electrode is made of a thin layer of a conductive material deposited on the input window. This particular embodiment has the advantage of being easy and inexpensive to implement.

Enfin, l'efficacité de transduction de la photoca­thode du tube photomultiplicateur selon l'invention peut être encore augmentée si les parois des trous de la première élec­trode émettrice comportent une couche d'un matériau réflecteur sur laquelle est déposé ledit matériau photoémissif. De cette manière, le trajet de la lumière incidente à travers le maté­riau photoémissif se trouve allongé par réflexion, ce qui tend à accroître la probabilité de transformation des photons en photoélectrons.Finally, the transduction efficiency of the photocathode of the photomultiplier tube according to the invention can be further increased if the walls of the holes of the first emitting electrode include a layer of reflective material on which said photoemissive material is deposited. In this way, the path of the incident light through the photoemissive material is elongated by reflection, which tends to increase the probability of transformation of photons into photoelectrons.

La description qui va suivre en regard des dessins annexés, donnés à titre d'exemples non limitatifs, fera bien comprendre en quoi consiste l'invention et comment elle peut être réalisée.

  • La figure 1 est une vue en coupe d'un tube photo­multiplicateur selon l'invention.
  • La figure 2 montre une coupe d'une variante de réa­lisation de l'étage d'entrée du tube photomultiplicateur de la figure 1.
The description which follows with reference to the appended drawings, given by way of nonlimiting examples, will make it clear what the invention consists of and how it can be implemented.
  • Figure 1 is a sectional view of a photomultiplier tube according to the invention.
  • FIG. 2 shows a section of an alternative embodiment of the input stage of the photomultiplier tube of FIG. 1.

La figure 1 représente, en coupe, un tube photomul­tiplicateur à N voies parallèles, N pouvant atteindre 64 par exemple. Ce tube comporte une fenêtre 10 d'entrée, en verre ou en quartz, et un multiplicateur 20 d'électrons du type "à pla­ques à trous", cloisonné en N multiplicateurs élémentaires 20a. Le premier étage du multiplicateur 20 d'électrons com­prend une électrode 30 d'entrée et une première électrode émettrice 40. Puis, on trouve dans les étages supérieurs une série de dynodes constituées de deux demi-dynodes en forme de plaques à trous, dont l'une, telle que D′₂ ou D′₃, est la demi-dynode extractrice, et l'autre, comme D₂ ou D₃, est la demi-dynode émettrice qui, douée d'émission secondaire, a pour rôle de multiplier les électrons incidents sur les parois de ses trous. Les deux demi-dynodes d'une même dynode sont por­tées au même potentiel électrique, alors que chaque dynode est portée à un potentiel électrique supérieur à celui de la dyno­de précédente. C'est pourquoi les demi-dynodes émettrice 40, D₂, D₃,..., sont séparées des demi-dynodes extractrices sui­vantes D′₂, D′₃,..., par des entretoises isolantes 60, comme des petites billes de résine par exemple. Ainsi que le montre la figure 1, les N multiplicateurs élémentaires 20a débouchent sur N anodes adjacentes 60a et sont séparés les uns des autres par des cloisons 21a étanches aux électrons, réalisées par masquage et photogravure.FIG. 1 represents, in section, a photomultiplier tube with N parallel channels, N being able to reach 64 for example. This tube has an entry window 10, made of glass or quartz, and an electron multiplier 20 of the "hole plate" type, partitioned into N elementary multipliers 20a. The first stage of the electron multiplier 20 comprises an input electrode 30 and a first emitting electrode 40. Then, there are in the upper stages a series of dynodes made up of two half-dynodes in the form of plates with holes, of which l one, such as D′₂ or D′₃, is the extracting half-dynode, and the other, like D₂ or D₃, is the emitting half-dynode which, endowed with secondary emission, has the role of multiplying the incident electrons on the walls of its holes. The two half-dynodes of the same dynode are brought to the same electrical potential, while each dynode is brought to an electrical potential greater than that of the preceding dynode. This is why the emitting half-dynodes 40, D₂, D₃, ..., are separated from the following extracting half-dynodes D′₂, D′₃, ..., by insulating spacers 60, like small balls of resin for example. As shown in FIG. 1, the N elementary multipliers 20a lead to N adjacent anodes 60a and are separated from each other by partitions 21a which are electron-tight, produced by masking and photoengraving.

Comme on peut le voir à la figure 1, les parois 41 des trous 42 de ladite première électrode émettrice 40 sont recouvertes d'un matériau photoémissif 43. A titre d'exemple, ledit matériau photoémissif peut être un antimoniure alcalin composé d'antimoine et d'un ou plusieurs alcalins parmi le po­tassium, le sodium et le césium. La première électrode émet­trice 40 joue alors le rôle de photocathode qui transforme les photons incidents 70 en photoélectrons 71 dont la vitesse ini­tiale n'est pas suffisante pour passer d'un trou à un autre, et qui, par conséquent, ne peuvent provoquer de diaphotie entre les voies. Dans le mode de réalisation montré à la figu­re 1, l'électrode 30 d'entrée est réalisée en une couche mince d'un matériau conducteur déposée sur la fenêtre 30 d'entrée. Cette électrode d'entrée assure une bonne transparence optique vis à vis des photons incidents 70 et, d'autre part, étant portée à un potentiel électrique égal ou faiblement inférieur à celui de la première électrode émettrice 40, elle assure le blindage de ladite première électrode émettrice de façon à éviter le retour des photoélectrons 71 sur les parois 41 des trous 42.As can be seen in FIG. 1, the walls 41 of the holes 42 of said first emitting electrode 40 are covered with a photoemissive material 43. By way of example, said photoemissive material can be an alkaline antimonide composed of antimony and one or more alkalines from potassium, sodium and cesium. The first emitting electrode 40 then plays the role of photocathode which transforms incident photons 70 into photoelectrons 71 whose initial speed is not sufficient to pass from one hole to another, and which, consequently, cannot cause crosstalk between the tracks. In the embodiment shown in Figure 1, the input electrode 30 is made of a thin layer of conductive material deposited on the input window 30. This input electrode ensures good optical transparency with respect to incident photons 70 and, on the other hand, being brought to an electrical potential equal to or slightly lower than that of the first emitting electrode 40, it ensures the shielding of said first emitting electrode so as to avoid the return of the photoelectrons 71 on the walls 41 of the holes 42.

La figure 2 montre un autre mode de réalisation de l'invention dans lequel les parois 41 des trous 42 de la pre­mière électrode émettrice 40 comportent une couche 44 d'un ma­tériau réflecteur sur laquelle est déposé ledit matériau pho­toémissif 43. La couche réflectrice 44 peut être, par exemple, constituée par de l'aluminium. Cette disposition avantageuse de l'invention a pour effet d'augmenter le trajet des photons incidents 70 à l'intérieur du matériau photoémissif 43 dans le but d'améliorer le rendement de transduction des photons incidents en photoélectrons 71.FIG. 2 shows another embodiment of the invention in which the walls 41 of the holes 42 of the first emitting electrode 40 comprise a layer 44 of a reflective material on which said photoemissive material 43 is deposited. The reflective layer 44 can be, for example, made up of aluminum. This advantageous arrangement of the invention has the effect of increasing the path of the incident photons 70 inside the photoemissive material 43 with the aim of improving the transduction efficiency of the incident photons into photoelectrons 71.

Toujours sur la figure 2, on observe que, dans le cas où l'électrode 30 d'entrée est une grille conductrice constituée de fils 31 disposés en regard des trous 42 de la première électrode émettrice 40, lesdits fils 31 ont une forme telle qu'ils réfléchissent la lumière incidente 70 sur les parois 41 desdits trous. La transparence optique de la grille 30 se trouve alors augmentée, ainsi que l'efficacité du tube photomultiplicateur selon l'invention.Still in FIG. 2, it can be seen that, in the case where the input electrode 30 is a conductive grid made up of wires 31 arranged opposite the holes 42 of the first emitting electrode 40, said wires 31 have a shape such that 'They reflect the incident light 70 on the walls 41 of said holes. The optical transparency of the grid 30 is then increased, as well as the efficiency of the photomultiplier tube according to the invention.

Claims (4)

1. Tube photomultiplicateur à N voies parallèles, com­portant une fenêtre (10) d'entrée et un multiplicateur (20) d'électrons du type "à plaques à trous", cloisonné en N multi­plicateurs élémentaires (20a), et dont le premier étage com­prend une électrode (30) d'entrée et une première électrode émettrice (40), caractérisé en ce que les parois (41) des trous (42) de ladite première électrode émettrice (40) sont recouvertes d'un matériau photoémissif (43).1. Photomultiplier tube with N parallel paths, comprising an inlet window (10) and an electron multiplier (20) of the "hole plate" type, partitioned into N elementary multipliers (20a), and the first stage of which comprises an input electrode (30) and a first emitting electrode (40), characterized in that the walls (41) of the holes (42) of said first emitting electrode (40) are covered with a photoemissive material (43) . 2. Tube photomultiplicateur selon la revendication 1, caractérisé en ce que les parois (41) des trous (42) de la première électrode émettrice (40) comportent une couche (44) d'un matériau réflecteur sur laquelle est déposé ledit maté­riau photoémissif (43).2. Photomultiplier tube according to claim 1, characterized in that the walls (41) of the holes (42) of the first emitting electrode (40) comprise a layer (44) of a reflective material on which is deposited said photoemissive material ( 43). 3. Tube photomultiplicateur selon l'une des revendica­tions 1 ou 2, caractérisé en ce que l'électrode (30) d'entrée est réalisée en une couche mince d'un matériau conducteur dé­posée sur la fenêtre (10) d'entrée.3. Photomultiplier tube according to one of claims 1 or 2, characterized in that the input electrode (30) is made of a thin layer of a conductive material deposited on the input window (10). 4. Tube photomultiplicateur selon l'une des revendica­tions 1 ou 2, caractérisé en ce que l'électrode (30) d'entrée est une grille conductrice constituée de fils (31) disposés en regard des trous (42) de la première électrode émettrice (40) et réfléchissant la lumière incidente (70) sur les parois (41) desdits trous.4. Photomultiplier tube according to one of claims 1 or 2, characterized in that the input electrode (30) is a conductive grid consisting of wires (31) disposed opposite the holes (42) of the first emitting electrode (40) and reflecting the incident light (70) on the walls (41) of said holes.
EP90202717A 1989-10-17 1990-10-12 Multi-path photomultiplier with high inter-signal resolution Withdrawn EP0423886A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8913541 1989-10-17
FR8913541A FR2653269B1 (en) 1989-10-17 1989-10-17 MULTICHANNEL PHOTOMULTIPLIER TUBE WITH HIGH RESOLUTION BETWEEN SIGNALS.

Publications (1)

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EP0423886A1 true EP0423886A1 (en) 1991-04-24

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EP (1) EP0423886A1 (en)
JP (1) JPH03147240A (en)
FR (1) FR2653269B1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0686996A1 (en) * 1994-06-06 1995-12-13 Hamamatsu Photonics K.K. Photomultiplier
GB2293685A (en) * 1994-09-29 1996-04-03 Era Patents Ltd Photomultipliers
FR2733629A1 (en) * 1995-04-26 1996-10-31 Philips Photonique ELECTRON MULTIPLIER FOR MULTI-CHANNEL PHOTOMULTIPLIER TUBE
WO2014146673A1 (en) * 2013-03-22 2014-09-25 Cern - European Organization For Nuclear Research A wall-less electron multiplier assembly

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5572089A (en) * 1993-04-28 1996-11-05 Hamamatsu Photonics K.K. Photomultiplier for multiplying photoelectrons emitted from a photocathode
EP0622828B1 (en) * 1993-04-28 1997-07-09 Hamamatsu Photonics K.K. Photomultiplier
DE69406709T2 (en) * 1993-04-28 1998-04-02 Hamamatsu Photonics Kk Photomultiplier

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FR2104171A5 (en) * 1970-08-13 1972-04-14 Philips Nv
EP0043629A1 (en) * 1980-07-09 1982-01-13 Philips Electronics Uk Limited Channel plate electron multiplier

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FR2104171A5 (en) * 1970-08-13 1972-04-14 Philips Nv
EP0043629A1 (en) * 1980-07-09 1982-01-13 Philips Electronics Uk Limited Channel plate electron multiplier

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IEEE TRANSACTIONS ON NUCLEAR SCIENCE. vol. NS-32, no. 1, February 1985, NEW YORK US pages 427 - 432; J G Timothy: "Electronic readout systems for microchannel plates" *
IEEE TRANSACTIONS ON NUCLEAR SCIENCE. vol. NS-34, no. 1, February 1987, NEW YORK US pages 449 - 452; J P Boutot et al.: "Multianode photomultiplier for detection and localization of low level events" *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0686996A1 (en) * 1994-06-06 1995-12-13 Hamamatsu Photonics K.K. Photomultiplier
US5801511A (en) * 1994-06-06 1998-09-01 Hamamatsu Photonics K.K. Photomultiplier
GB2293685A (en) * 1994-09-29 1996-04-03 Era Patents Ltd Photomultipliers
GB2293685B (en) * 1994-09-29 1998-02-04 Era Patents Ltd Photomultiplier
FR2733629A1 (en) * 1995-04-26 1996-10-31 Philips Photonique ELECTRON MULTIPLIER FOR MULTI-CHANNEL PHOTOMULTIPLIER TUBE
WO2014146673A1 (en) * 2013-03-22 2014-09-25 Cern - European Organization For Nuclear Research A wall-less electron multiplier assembly

Also Published As

Publication number Publication date
JPH03147240A (en) 1991-06-24
FR2653269B1 (en) 1992-05-22
FR2653269A1 (en) 1991-04-19

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