EP0000271B1 - Kathodenplatte; lageempfindlicher Messfühler für neutrale Teilchen mit einer derartigen Kathodenplatte; Fühlersystem und Kamera, beide mit einem derartigen Messfühler - Google Patents

Kathodenplatte; lageempfindlicher Messfühler für neutrale Teilchen mit einer derartigen Kathodenplatte; Fühlersystem und Kamera, beide mit einem derartigen Messfühler Download PDF

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Publication number
EP0000271B1
EP0000271B1 EP19780300075 EP78300075A EP0000271B1 EP 0000271 B1 EP0000271 B1 EP 0000271B1 EP 19780300075 EP19780300075 EP 19780300075 EP 78300075 A EP78300075 A EP 78300075A EP 0000271 B1 EP0000271 B1 EP 0000271B1
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Prior art keywords
cathode
strips
neutral particle
sensor
array
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Expired
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EP19780300075
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English (en)
French (fr)
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EP0000271A1 (de
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James Edmond Bateman
John Francis Connolly
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BTG International Ltd
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National Research Development Corp UK
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J47/00—Tubes for determining the presence, intensity, density or energy of radiation or particles
    • H01J47/06—Proportional counter tubes

Definitions

  • This invention relates to a cathode plate for use in a position-sensitive neutral particle sensor comprising an insulating support having a cathode array of spaced metal strips arranged adjacent and edge to edge, the metal of which the strips are formed being such that an incident neutral particle gives rise to an ionising particle which is either a photoelectron or a Compton electron and which escapes from the cathode plate.
  • neutral particles are X-rays, y-rays and neutrons.
  • This invention relates further to a position sensitive neutral particle sensor using such a cathode plate, and to a sensing system and to a camera both using such a sensor.
  • a cathode plate according to the first part of claim 1 is known from FR-A-2 176 496. From the journal 'Physics in Medicine and Biology', Vol. 20, 1975, page 136-141 a position sensitive particle sensor is known for detecting y-rays of approximately 510 keV by photoelectrons and Compton electrons produced by them, the sensor comprising a lead foil having cathode arrays which are parallel and closely spaced, with the strips of neighbouring cathode arrays being mutually orthogonal; means for connecting each strip of each cathode array to a known electrical potential, in the space between the cathode arrays an anode array comprising a plurality of spaced wires, means for connecting all of the wires in each anode array to a source of electrical potential; means for supplying a gas to the volume around each anode array; and means for sensing separately the presence of an induced electrical charge in at least one strip of both cathode arrays adjacent one anode array and for providing output
  • a multiple position-sensitive neutral particle sensor comprising a plurality of cathode plates. From the Report CERN-77--Ol, 6 January 1977, it is known to detect thermal neutrons by detection of the electrons produced by them in a gadolinium foil. From the journal 'Kernenergie' 12, No. 4, 1969, pages 132-133 a y-ray sensor is known comprising a position-sensitive neutral particle sensor and a collimator arranged to allow the passage of y-rays only in a direction substantially perpendicular to the plane of the cathode arrays.
  • the invention is intended to increase the detection efficiency of a position-sensitive neutral particle sensor by a cathode plate having for a given incident neurtal particle an optimized gain of ionizing particles escaping from the cathode plate.
  • a cathode plate as previously described has an insulating support having a thickness which prevents absorption of said ionising particle, having a cathode array on each face, and the thickness of each metal strip in each cathode array is approximately half the preferred thickness provided from theoretical calculations.
  • a position-sensitive neutral particle sensor comprises a plurality of cathode plates as previously described, the cathode plates being parallel to each other and closely spaced with the strips in the cathode arrays on adjacent faces of neighbouring plates being mutually orthogonal and the two outer cathode plates having cathode arrays only on the inner side of the insulating support;
  • anode array comprising a plurality of spaced wires
  • a particular embodiment of the sensor may further comprise means for sensing the arrival of electrons at an anode array.
  • a position-sensitive neutral particle sensing system comprises a sensor as previously described and display means arranged to provide an orthogonal display for each of the received particles.
  • Figure 1 is an exploded sketch view illustrating how a single neutral particle is sensed by two arrays of cathode strips and one anode array.
  • a position-sensitive neutral particle sensor comprises first and second planar cathode arrays 10, 12, and a planar anode array 14, all three arrays being parallel and the anode array being between the cathode arrays.
  • the first cathode array 10 consists of a series of strips 16 of metal foil, arranged closely spaced edge-to-edge in the cathode plane but insulated from each other; one end of each strip is connected to earth through a 220 kQ resistor 17, and the other end of each strip is connected to a delay line 18 which can provide an output signal V,.
  • the second cathode plane is similar, consisting of a series of strips 20 arranged with their longitudinal direction at 90° to the strips in the first cathode plane, earthed through resistors 19 and connected to a delay line 22 which can provide an output signal V 2 .
  • the anode plane 14 consists of a series of spaced metal wires 24 each connected at one end to a common lead 26 through which a positive electrical potential is supplied to each wire and which also can provide an output signal V o through a capacitor 28.
  • the anode wires are arranged at 45° to the cathode strips. This is not essential; the wires can be parallel to one array of strips, or make an angle other than 0°, 45° or 90° with the cathode strips.
  • a gas (not shown) such as the gas used in a conventional multiwire proportional counter, is supplied to surround the cathode and anode arrays.
  • a source of neutral particles represented by reference 30, emits a particle along a path 32 towards the sensor.
  • the metal foil cathodes are of the correct material and thickness, considering the energy of the incident particle, the particle is absorbed by one cathode strip and a fast electron 34 is emitted into the gas; this electron has a speed approaching relativistic values and may be a photoelectron or a Compton electron.
  • the fast electron ionises gas atoms to produce secondary ions and electrons.
  • the ions drift slowly towards the cathode and can be ignored.
  • the electrons are attracted towards the anode along the path 36 and as they approach an anode wire closely, encounter a very high electric field. An avalanche of electrons and positive ions is initiated.
  • the electrons are attracted to the anode wire, and are released into the external anode circuit by the movement of the positive ion cloud 38 away from the anode wires, and generate a negative output signal V at a time which is very shortly after the time of arrival of the initial neutral particle, and can be regarded as indicating the time of that arrival.
  • the movement of the cloud of ions away from the anode wires also generates an electrostatic induction field 40, which in turn results in a positive charge pulse in several cathode strips in each array.
  • Each strip provides a positive output pulse; the cathode strips immediately above and below the electron avalanche provide the largest signals; adjacent strips receive less charge and provide lower signals.
  • the output pulses from the strips in each cathode array are coupled onto the respective delay lines 18, 22, and the delay lines, in effect, merge the separate pulses to provide a single pulse, slightly spread in time, which travels along the delay line; the time of arrival of the pulse maximum at the delay line output can be related to the position along the delay line of the strip receiving maximum charge.
  • each cathode array Since the strips in each cathode array are arranged orthogonally, the x-y co-ordinates of the electron avalanche, and thus the position of the received neutral particle, can be determined.
  • Such an arrangement of delay lines and time measurement means is well known in the field of multiwire proportional counters.
  • the multiple sensor comprises twenty cathode arrays 50 and ten anode arrays 52.
  • Each cathode array comprises a series of strips of metal foil supported by a film of a suitable plastics material, such as polyethylenetera- phthalate; an example is a Kaptan (Registered Trade Mark) film 12.5 microns thick.
  • the two outer cathodes have metal strips on only the inner side of the film, but the other cathodes have strips, in the same orthogonal direction, on both sides of the film.
  • the films are supported at their edges between spacers 54 which are bolted together to form a rigid stack, and the spacers are bolted to a base board 55.
  • each cathode array acts as a converter for a neutral particle as well as a position read-out.
  • the material and the thickness of the cathode strips must be chosen in accordance with the energy of the neutral particle to be detected, considering the binding energy of the converter material and the escape probability of a fast electron produced in the material; the escape probability varies with thickness.
  • each cathode strip in Figure 2 may be made of copper about 5 microns thick.
  • each cathode strip in Figure 2 may be made of tin about 12.5 microns thick, and-a typical multiple sensor would comprise 20 to 25 sensors.
  • each cathode strip in Figure 2 may be made of lead about 125 microns thick, and a typical counter would comprise 10 to 15 sensors.
  • each cathode strip in Figure 2 may be made of gadolinium about 10 microns thick.
  • each thickness is half the preferred thickness provided from the calculations; this is because each inner cathode array is spaced very close to another cathode array, the combination giving the desired thickness; the insulating film between the two arrays must be very thin to prevent absorption of the fast electrons.
  • the spacing between each anode and the adjacent cathodes is 4 millimetres.
  • the anode wires may, for example, be gold-plated tungsten wires 20 microns in diameter, spaced at 2 millimetres.
  • the baseboard 55 carrying the spacers 54 is supported by lips 64 within a gas-tight enclosure 66, for example a glass fibre-epoxy composite box. Conveniently the array of electrodes 58 and the delay lines 62 are outside the container. A gas inlet tube 68 and gas outlet tube 70 are provided.
  • any gas conventionally used in a multiwire proportional counter may be used; the more dense the gas, the better the spatial resolution of the counter.
  • Xenon or 2-2 dimethylpropane or pure isobutane or a mixture of 70% argon and 30% isobutane may be used. It is an advantage of a counter according to the invention, in which the anode-cathode spacing can be quite small, that slightly electronegative gases can be used.
  • the gas is caused to flow continuously through the sensor; the gas may need to be at a pressure higher than atmospheric pressure.
  • the gas does not convert neutral particles to fast electrons, as in a conventional multiwire proportional counter, but provides a medium in which an electron avalanche and ion cloud can be initiated by a fast electron produced in the cathode of the device by a neutral particle.
  • Figure 2 shows that some cathode strips are arranged with their length parallel to the plane of the Figure, such as in cathode arrays 50A, 50B, 50C, while other cathode strips are arranged with their length perpendicular to the plane of the Figure, such as in cathode arrays 50D, 50E.
  • a bussed arrangement allows a much simpler readout system to be used.
  • the anode arrays are not bussed vertically, because a signal indicating in which anode plane an electron avalanche is received may be required to give the z co-ordinate.
  • Suitable electrical readout circuitry is shown in Figure 3.
  • the arrays of cathode strips 16 and 20 and the anode wires 24 are indicated schematically.
  • the delay lines 18, 22 are connected through respective amplifiers 72, 74 and discriminators 76, 78, each to one input of respective time-to-amplitude converters (TAC) 80, 82, which supply respectively the x and y signals to a display unit 84.
  • TAC time-to-amplitude converters
  • the anode array is connected through an amplifier 86 and discriminator 88 to the other input of each TAC 80, 82.
  • the amplifier 86 is also connected to a linear gate 90 both directly and through the discriminator 88, and the gate is connected to the display unit 84 through a single channel analyser (SCA) 92 and delay device 94.
  • SCA single channel analyser
  • a negative pulse reference 96
  • this pulse is used as a prompt pulse for the circuit.
  • the prompt pulse causes the TAC's 80, 82 to start; arrival of the respective positive pulses 98, 100 from the cathodes through the delay lines stops the TAC's.
  • the TAC output signals indicate the co-ordinates in the x-y plane of an initiating neutral particle event, and a display is provided on the display unit 84 at the corresponding position on the screen.
  • the prompt pulse also provides a bright-up pulse for the display unit 84, through the SCA 92, which integrates the total charge deposited in the counter by the electron avalanche and acts as a pulse height selector, and through the delay device 94 which delays the bright-up pulse by a time interval required by the display system 84.
  • a picture may be built up, either by using a storage oscilloscope as the display unit, or by use of photographic methods or of a digital computer.
  • a large sensing area may be provided, for example of the order of one square metre.
  • the sensor may be used as a gamma camera to detect gamma radiation emitted by an organ of the human body after the administration of 99m Technicium in suitable form.
  • FIG. 4 An example of such an arrangement is illustrated in Figure 4 in which a gamma camera comprising a multiple position-sensitive neutral particle sensor according to the invention 102, is connected through suitable circuitry 103 to a display unit 104.
  • a collimator 106 consisting of a lead plate 25 millimetres thick and having a matrix of parallel open channels of about 4 millimetres diameter, is arranged between the sensor and a live human body 108. In this arrangement, the collimator 106 absorbs all gamma rays which do not pass substantially vertically upwards, and a two-dimensional picture of a gamma-ray emitting organ is obtained.
  • a positron-emitting substance is administered to a patient.
  • Two multiple position-sensitive neutral particle sensors may be arranged to detect the gamma rays emitted back-to-back by positron annihilation.
  • Such an arrangement is shown in Figure 5 in which two multiple sensors according to the invention 110, 112 are spaced above and below a live human body 114.
  • the sensors are connected through suitable circuitry 116 to a display unit 118 in such a way that only coincident gamma rays are displayed and a reconstruction of the distribution of the positron emitting substance within the live human body is exhibited on the display unit 118 by means of a suitable computer.

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  • Measurement Of Radiation (AREA)
  • Catalysts (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Claims (11)

1. Kathodenplatte zur Verwendung in einem positionsempfindlichen Sensor für neutrale Teilchen, mit einer isolierenden Unterlage, die eine Kathodenanordnung beabstandeter Metallstreifen aufweist, welche benachbart und Kante an Kante angeordnet sind, wobei das Metall, aus denen die Streifen gebildet sind, von der Art ist, daß ein einfallendes neutrales Teilchen ein ionisierendes Teilchen bewirkt, welches entweder ein Photoelektron oder ein Comptonelektron ist und welches aus der Kathodenplatte entweicht, dadurch gekennzeichnet, daß die isolierende Unterlage eine Dicke aufweist, welche die Absorption des ionisierenden Teilchens verhindert, und eine Kathodenanordnung auf jeder Oberfläche umfaßt, und daß die Dicke jedes Metallstreifens in jeder Kathodenanordnung etwa die Hälfte der bevorzugten Dicke beträgt, die sich aus theoretischen Berechnungen ergibt.
2. Kathodenplatte nach Anspruch 1, dadurch gekennzeichnet, daß beide Kathodenanordnungen (50D, 50E) identisch sind und die Streifen in der gleichen orthogonalen Richtung auf beiden Seiten der isolierenden Unterlage liegen.
3. Kathodenplatte nach Anspruch 1 oder 2 zum Abtasten von Röntgenstrahlen mit einer Energie von etwa 60 keV, dadurch gekennzeichnet, daß beide Kathodenanordnungen aus 5 ,um dicke Kupferstreifen bestehen.
4. Kathodenplatte nach Anspruch 1 oder 2 zum Abtasten von Gammastrahlen, die eine Energie von etwa 140 keV aufweisen, dadurch gekennzeichnet, daß beide Kathodenanordnungen aus 12,5 µm dicken Zinnstreifen bestehen.
5. Kathodenplatte nach Anspruch 1 oder 2 zum Abtasten von Gammastrahlen, die eine Energie von etwa 510 keV aufweisen, dadurch gekennzeichnet, daß beide Kathodenplatten aus 125 µm dicken Bleistreifen bestehen.
6. Kathodenplatte nach Anspruch 1 oder 2 zum Abtasten thermischer Neutronen, die eine Energie von etwa 100 MeV aufweisen, dadurch gekennzeichnet, daß beide Kathodenanordnungen aus 10 µm dicken Gadoliniumstreifen bestehen.
7. Positionsempfindlicher Sensor für neutrale Teilchen, gekennzeichnet durch mehrere Kathodenplatten (50) nach einem der vorhergehenden Ansprüche, die parallel zueinander und eng beieinander liegen, wobei die Streifen in den Kathodenanordnungen auf benachbarten Oberflächen benachbarter Kathodenplatten orthogonal zueinander angeordnet sind, und die zwei äußeren Kathodenplatten nur an der Innenseite der isolierenden Unterlage Kathodenanordnungen aufweisen, ferner durch eine Einrichtung (56, 58) zum Anschließen jedes Streifens jeder Kathodenanordnung an ein bekanntes elektrisches Potential, eine Anodenanordnung (52) in jedem Zwischenraum zwischen den Kathodenplatten, welche eine Mehrzahl beabstandeter Drähte umfaßt, eine einrichtung zum Anschließen sämtlicher Drähte in jeder Anodenanordnung (52) an eine elektrische Potentialquelle, eine Einrichtung (66, 70) zur Zuführung eines Gases zu einem Raumbereich um jede Anodenanordnung (52) herum sowie eine Einrichtung (62, 72, 74, 76, 78, 80, 82, 84) zum Abtasten des Vorhandenseins einer induzierten elektrischen Ladung in wenigstens einem Streifen beider einer Anodenanordnung (52) benachbarten Kathodenanordnungen (50) und wobei die induzierte elektrische Ladung von der Ankunft eines neutralen Teilchens in dem Sensor herrührt, zum Liefern von Ausgangssignalen, die die orthogonale Position dieses neutralen Teilchens in den Kathodenanordnungen wiedergeben.
8. Sensor nach Anspruch 7, gekennzeichnet durch eine Einrichtung (86) zum Abtasten der Ankunft von Elektronen an einer Anodenanordnung (52).
9. Positionsempfindliches Sensorsystem für neutrale Teilchen nach Anspruch 7 oder 8, gekennzeichnet durch einen Sensor nach Anspruch 7 oder 8 und eine Bildaufzeichnungseinrichtung (84) zum Vorsehen einer orthogonalen Bildaufzeichnung für jedes der empfangenen Teilchen.
10. Für Gammastrahlen oder Röntgenstrahlen empfindliche Kamera, gekennzeichnet durch einen positionsempfindlichen Vielfachsensor für neutrale Teilchen (102, 103) nach Anspruch 7 oder 8 sowie einen Kollimator 106, der so angeordnet ist, daß er Gammastrahlen oder Röntgenstrahlen nur in einer Richtung durchläßt, die im wesentlichen senkrecht zur Ebene der Kathodenanordnungen ist.
11. Für Positronen empfindliche Kamera, gekennzeichnet durch zwei beabstandete Vielfachsensoren (110, 112) nach Anspruch 7 oder 8 sowie eine Koinzidenzabtasteinrichtung (116), die darauf eingerichtet ist, die gleichzeitige Ankunft eines neutralen Teilchens in jedem Abtastsystem abzutasten.
EP19780300075 1977-06-24 1978-06-23 Kathodenplatte; lageempfindlicher Messfühler für neutrale Teilchen mit einer derartigen Kathodenplatte; Fühlersystem und Kamera, beide mit einem derartigen Messfühler Expired EP0000271B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB2659677 1977-06-24
GB2659677A GB1583571A (en) 1977-06-24 1977-06-24 Hydrocarbon synthesis from co and h2 with ru ni or rh supported on a titanium oxide

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EP0000271A1 EP0000271A1 (de) 1979-01-10
EP0000271B1 true EP0000271B1 (de) 1981-12-02

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DE (1) DE2861396D1 (de)
GB (1) GB1583571A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4018859A1 (de) * 1990-06-13 1992-01-02 Besch Hans Juergen Dr Bildgebender detektor fuer (gamma)-strahlung

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4477595A (en) * 1982-03-31 1984-10-16 Exxon Research And Engineering Co. Liquid hydrocarbon synthesis using supported ruthenium catalysts
US4513161A (en) * 1984-06-29 1985-04-23 Exxon Research And Engineering Co. Conversion of methanol to hydrocarbons
FR2638567B1 (fr) * 1988-10-28 1996-06-07 Schlumberger Ind Sa Procede et dispositif de localisation bidimensionnelle de particules neutres
FR2639436B1 (fr) * 1988-10-28 1994-07-01 Schlumberger Ind Sa Procede et dispositif de localisation de particules neutres, a haute resolution
FR2638536B1 (fr) * 1988-10-28 1994-07-29 Schlumberger Ind Sa Procede et dispositif de localisation de particules neutres pour faibles taux de comptage
EP0441853B1 (de) * 1988-10-28 1994-10-12 Schlumberger Industries Verfahren und vorrichtung zur bidimensionalen lokalisierung nichtgeladener partikel, insbesondere bei geringer zählrate
KR101516812B1 (ko) * 1998-02-16 2015-04-30 스미또모 가가꾸 가부시끼가이샤 염소의 제조방법
CN1915800B (zh) * 1998-02-16 2011-12-07 住友化学株式会社 氯的制备方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2176496A2 (en) * 1972-03-21 1973-11-02 Commissariat Energie Atomique Neutron detector - with cartesian coordinate beam position read out

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4018859A1 (de) * 1990-06-13 1992-01-02 Besch Hans Juergen Dr Bildgebender detektor fuer (gamma)-strahlung

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GB1583571A (en) 1981-01-28
EP0000271A1 (de) 1979-01-10

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