GB1598962A - Arrangement for detecting radiation - Google Patents

Arrangement for detecting radiation Download PDF

Info

Publication number
GB1598962A
GB1598962A GB1125478A GB1125478A GB1598962A GB 1598962 A GB1598962 A GB 1598962A GB 1125478 A GB1125478 A GB 1125478A GB 1125478 A GB1125478 A GB 1125478A GB 1598962 A GB1598962 A GB 1598962A
Authority
GB
United Kingdom
Prior art keywords
electrode
wall
chamber
radiation
radiation detecting
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.)
Expired
Application number
GB1125478A
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.)
Siemens AG
Original Assignee
Siemens AG
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 Siemens AG filed Critical Siemens AG
Priority to GB1125478A priority Critical patent/GB1598962A/en
Publication of GB1598962A publication Critical patent/GB1598962A/en
Expired legal-status Critical Current

Links

Classifications

    • 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
    • H01J47/02—Ionisation chambers

Landscapes

  • Measurement Of Radiation (AREA)

Description

(54) ARRANGEMENT FOR DETECTING RADIATION (71) We, SIEMENS AKTIENGESELLSCAFT, a German company of Berlin and Munich, Germany, do hereby declare the invention, for which we pray that a patent may be granted tc us, and the method bv which it is to be performed, to be particularly described in and by the following statement: This invention relates to an arrangement for detecting radiation.
In particle accelerators which are used for irradiating a field, whether with gamma radiation, electrons or charged atomic nuclei, it is necessary to monitor radiation issuing from the accelerator. It is not only the total radiation intensity issuing which is of interest, but also its uniform distribution within the cone of rays leaving the accelerator tube and the components connected to this at the outlet side, such as for example target, electron absorber, compensating body, lateral magnets, etc.
Ionization chambers are generally used for this.
Each ionization chamber ascertains the mean value of the dose output emitted in the volume detected by the chamber. In order to receive information about the intensity distribution within a cone of rays, a matrix of punctiform ionization chambers would be required. This is not desirable however, not only because of financial considerations but also because, technically, it is hardly feasible. One is therefore anxious to use an ionization chamber which is as simple as possible and which also makes possible information about the intensity distribution in the cone of rays.
For this purpose it has been proposed in U.S.Patent Specification 3 852 610 to construct an arrangement for use in particle accelerators in which two disc-shaped measuring chambers are formed between three mutually parallel walls. The two outer walls of the measuring chambers consist of a film, on which a single continuously conductive layer, i.e. a single electrode, is applied. A mica layer is used for the middle wall of this ionization chamber on which two concentric electrode rings, whose conductive layers are each sub divided into four individual electrodes in a segment-like manner, are led out to separate connection terminals.
With this ionization chamber, which is manufactured with advantageous intrinsic absorbtion values, the fact that it does not respond to all types of inhomogeneities of the dose output in ihe emanating cone of rays was felt to be disadvantageous.
Further improvements with regard to the information content ralative to the homogeneity of the dose output in the cone of rays were proffered in an arrangement disclosed in U.S.
Patent Specification 3 942 012.
According to the invention there is provided a radiation detecting arrangement comprising first and second ionization chambers provided by spaced-apart, substantially parallel walls, which comprise first and second walls and an intermediate wall arranged between them, the first chamber being between the first wall and the intermediate wall and the second wall, in which arrangement the first wall is provided, inside the first chamber, with an electrode for the first chamber, the intermediate wall comprises or is provided with a common electrode for the first and second chambers, and the second wall is provided, inside the second chamber, with a plurality of mutually insulated electrodes for the second chamber, the mutually insulated electrodes comprising a substantially disc-shaped electrode, in annular arrangement of several independent electrodes substantially surrounding the substantially discshaped electrode, and a further electrode surrounding the said independent electrodes.
Thus, two different measuring chambers are obtained without increasing the number of chamber walls. This makes possible information relative to the dose output integrated over the entire surface of the cone of rays from the first ionization chamber and, from the second ionization chamber information relative to the dose output in specific selected regions of the cone of rays. Moreover, the summations of the ionization currents in both ionization chambers, relative to their surface, can be compared with each other. If their values, relative to their surfaces, are unequal, this indicates an error, either in one of the ionization chambers or in signal processing means connected at the outlet side.
The intermediate wall could comprise a fine mesh which forms the common electrode for the first and second chambers. Alternatively, the first, second and intermediate walls could comprise first, second and third plastics films respectively. In the latter case, the electrode for the first chamber and the common electrode for the first and second chambers could each comprise nickel gauze which has been applied, by an etching method, to the inside of the first plastics film and both sides of the third plastics film respectively. Alternatively, the electrode for the first chamber, the electrode for the second chamber, and the common electrode for the first and second chambers could each comprise electrodes which have been evaporated on the first, second and third plastics films respectively.
The invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a cross-section through a radiation detecting arrangement for the examination of an X-ray cone, Figure 2 shows a view of an electrode of the radiation detecting arrangement shown in Figure 1, Figure 3 shows a view of a plurality of mutually insulated electrodes of a second chamber wall of the radiation detecting arrangement shown in Figure 1, and Figure 4 shows a radiation detecting arrangement for the examination of an electron beam cone.
Referring to Figure 1, a radiation detecting arrangement 1 comprises three ceramic discs 2, 3 and 4 held together, with two spacer rings 5 and 6 made of ceramic material disposed between the discs 2 and 3 and the discs 3 and 4 respectively such that first and second measuring ionization chambers 7 and 8 respectively are formed. The intermediate and one of the outer ceramic discs (3 and 2 respectively) each have a fine bore 10 and 9 respectively. In this example, the fine bores 9 and 10 each have a diameter of 2mm. The bore 9 in the outer ceramic disc 2 is closed by a compression tube 11. The sides of the individual ceramic discs which are facing each other are provided with conductive surfaces - the electrodes 12, 13, 14, 15, 16, 17, 18, 19 and 20 (see also Figure 3).
Referring to Figure 2, it can be seen that the undivided electrode 12 completely covers and obscures the entire surface of the ceramic disc 2. The electrodes 12, 13 and 14 have exactly the same appearance. In the case of the central ceramic disc 3 the conductive upper surface electrode 13 also connects with the conductive surface electrode 14 (arranged on the other side of the disc 3) by extending through the bore 10. This disc 3 and its conductive surface electrodes 13 and 14 could be replaced by a fine mesh, forming a common electrode for the first and second ionization chambers 7 and 8.
Referring to Figure 3, there can be seen six different electrodes 15, 16, 17, 18, 19 and 20 which are arranged on the ceramic disc 4 shown in Figure 1. A central circular discshaped measuring electrode 19 is provided with four connections 21,22,23 and 24 which are con ducted almost to the edge of the ceramic disc 4.
An electrode ring is located some distance away from the centre of the ceramic disc 4, which ring comprises four individual circularly-arranged and mutually insulated measuring electrodes 15, 16, 17 and 18, and their connections 25, 26, 27 and 28 respectively. A con ductive surface is located outside these four measuring electrodes 15, 16, 17 and 18, surrounding them and their respective connections to provide an auxiliary electrode 20.
The outer periphery of the four circularlyarranged measuring electrodes 15, 16, 17 and 18 just corresponds to the outer periphery of a cone of rays within the radiation detecting ar iangement 1. The ends of all the connections 21 to 28 applied on the ceramic disc 4 are each - terminated by a small pierced circular disc. On the outer side of the ceramic disc 4 contact lugs 29 to 36 are attached under respective ends of the induvidual connections 21 to 28 and are in contact with them via bores. The auxiliary electorde 20 of the ceramic disc 4 and the undivided electrodes 12, 13, 14 of the other two ceramic discs 2 and 3 abut metal rings 40, 37, 38 and 39, respectively which are inserted between the ceramic discs 2, 3 and 4 and the spacer rings 5 and 6 (see Figure 1).The project ing outer peripheries of these rings 37 to 40 serve as contact terminals.
During operation of the radiation detecting arrangement 1, the electrodes 13 and 14 on respective sides of the middle ceramic disc 3 are at a high voltage. This high voltage is only connected to one of the two metal rings 38 and 39, and, because of the conductive link through the bore 10, the other relevant electrode 13 or 14 is therefore simultaneously connected. The application of the high voltage may thus be achieved via either one of the metal rings 38 and 39. The auxiliary electrode 20 of the ceramic disc 4 is earthed. Its mutually insulated measuring electrodes 15 to 19 are at approximately earth potential. In this way, the electrical field is divided, in the region of the second ionization chamber 8 (see Figure 1), into five different, defined regions. The electrical field in the first ionization chamber 7, provided with the two single-part electrodes 12 and 13, is not divided. The measuring volume, however, is exactly defined by the limitation of the chamber volume by the spacer ring 5.
Ions are produced by radiation in the gas volume of the two ionization chambers 7 and 8.
These ions are accelerated due to the potential difference between the relevant measuring electrodes 12 and 15 to 19 and the respective opposite electrodes 13 and 14 in accordance with their respective polarities. The current between the individual mutually opposite electrodes is, in the case of correct chamber voltage and medium radiation intensity, exactly proportional to the radiation intensity in the chamber volume in the region of the relevant measuring electrode. When the radiation intensity in the cone of rays is completely homogeneous, the currents in the measuring electrodes are equal, being relative to the chamber volume assigned to each electrode and so, in this case, relative to the surface area of each electrode.If the currents through the individual equal area, circularly-arranged measuring electrodes 15 to 18 differ, an unsymmetrical distribution of the radiation intensity in the cone of rays is indicated. If, on the other hand, the currents through the individual circularly-arranged measuring electrodes 15 to 18 are equal, but different with respect to the current through the central circular disc-shaped measuring electrode 19, then this indicates an inhomogeneity of the radiation intensity rn ihe sone of which is symmetrical to the axis of symmetry of the radiation detection arrangement 1, i.e. to the centre of the cone of rays. Tests have shown that the greatest sensitivity to such inhomogeneities which are symmetrical to the centre of the cone of rays is achieved when the centre of the cone of rays is compared with its peripheral regions.The four measuring electrodes 15 to 18 are arranged in these peripheral regions of the cone of rays.
Finally, Figure 4 shows a cross-section through a radiation measuring arrangement 41 which is particularly suitable for measuring an electron cone of rays. With this radiation measuring arrangement 41 the use of continuous ceramic discs for the division of first and second measuring ionization chambers 42 and 43 respectively was dispensed with because of the particularly low intrinsic absorption required of them. Instead, the radiation measuring arrangement 41 comprises four superposed metal rings 44,45,46 and 47, between which are clamped three plastics films 48, 49 and 50, each having a conductive coating. The two outer metal rings 44 and 47 are somewhat larger in diameter than the inner metal rings 45 and 46. The rings 44 and 47 are provided at their peripheries with openings 51 and 52 respectively by means of which they can be screwed to one another and mounted together.
The plastics films 48 and 49 are coated in the same way as shown in the Figure 2, but without the opening 9. The plastics film 50 is coated in the same way as the ceramic disc 4 (Figure 3).
The two inner metal rings 45 and 46 simultaneously serve as electrical connections for the adjacent conductive surfaces on both sides of the intermediate plastics film 49. Annular insulating discs 54 and 55 are located on respective sides of the two inner metal rings 45 and 46 and facing the two plastics films 48 and 50 respectively. Thin contact rings 56 and 57 are inserted between respective ones of these insulating discs 54 and 55 and the outer plastics films 48 and 50. The conductive surfaces of the plastics films 48 and 50. The conductive surfaces of the plastics films 48 and 50 facing the ionization chambers 42 and 43 respectively at their outer peripheries. The lower metal ring 47 is provided with a row of openings which are aligned parallel to its axis of symmetry.Individual electrical connections are passed through these openings to the electrode surfaces of the clamped plastics film 50 which is coated in accordance with the pattern shown in Figure 3.
Electrical connections 58, 59, 60, 61 and 62 are guided out of this metal ring 47 in an insulated manner.
WHAT WE CLAIM IS: 1. A radiation detecting arrangement comprising first and second ionization chambers provided by spaced-apart, substantially parallel walls, which walls comprise first and second walls and an intermediate wall arranged them, 1 tF~Faz, the tMrt sh nber being between he firs i all and the msermediate wall and the second chamber being between the illtermedi ate wall and the second wall, in which arrangement the first wall is provided, inside the first chamber, with an electrode for the first chamber, the intermediate wall comprises or is provided with a common electrode for the first and second chambers, and the second wall is provided, inside the second chamber, with a plurality of mutually insulated electrodes for the second chamber, the mutually insulated electrodes comprising a substantially discshaped electrode, an annular arrangement of several independent electrodes substantially surrounding the substantially disc-shaped electrode, and a further electrode surrounding the said independent electrodes.
2. A radiation detecting arrangement according to Claim 1, further comprising a first spacing member, for spacing-apart the first wall and the intermediate wall, and a second spacing member, for spacing apart the second wall and the intermediate wall.
3. A radiation detecting arrangement acccording to Claim 2, wherein the first and second spacing members are ring-shaped.
4. A radiation detecting arrangement according to any preceding claim, further comprising a plurality of terminals connected with respective ones of the said mutually insulated electrodes.
5. A radiation detecting arrangement according to Claim 4, wherein the terminals extend from the remainder of the arrangement.
6. A radiation detecting arrangement according to any preceding claim, wherein the second wall is substantially disc-shaped.
7. A radiation detedting arrangement according to Claim 6, wherein the said substantially disc-shaped electrode is substantially central with respect to the second wall.
8. A radiation detecting arrangement according to any preceding claim, wherein the first wall and the intermediate wall are both substantially disc-shaped.
9. A radiation detecting arrangement according to any preceding claim, wherein the first, second, and intermediate walls are made
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (1)

  1. **WARNING** start of CLMS field may overlap end of DESC **.
    electrode. When the radiation intensity in the cone of rays is completely homogeneous, the currents in the measuring electrodes are equal, being relative to the chamber volume assigned to each electrode and so, in this case, relative to the surface area of each electrode. If the currents through the individual equal area, circularly-arranged measuring electrodes 15 to 18 differ, an unsymmetrical distribution of the radiation intensity in the cone of rays is indicated.If, on the other hand, the currents through the individual circularly-arranged measuring electrodes 15 to 18 are equal, but different with respect to the current through the central circular disc-shaped measuring electrode 19, then this indicates an inhomogeneity of the radiation intensity rn ihe sone of which is symmetrical to the axis of symmetry of the radiation detection arrangement 1, i.e. to the centre of the cone of rays. Tests have shown that the greatest sensitivity to such inhomogeneities which are symmetrical to the centre of the cone of rays is achieved when the centre of the cone of rays is compared with its peripheral regions. The four measuring electrodes 15 to 18 are arranged in these peripheral regions of the cone of rays.
    Finally, Figure 4 shows a cross-section through a radiation measuring arrangement 41 which is particularly suitable for measuring an electron cone of rays. With this radiation measuring arrangement 41 the use of continuous ceramic discs for the division of first and second measuring ionization chambers 42 and 43 respectively was dispensed with because of the particularly low intrinsic absorption required of them. Instead, the radiation measuring arrangement 41 comprises four superposed metal rings 44,45,46 and 47, between which are clamped three plastics films 48, 49 and 50, each having a conductive coating. The two outer metal rings 44 and 47 are somewhat larger in diameter than the inner metal rings 45 and 46. The rings 44 and 47 are provided at their peripheries with openings 51 and 52 respectively by means of which they can be screwed to one another and mounted together.
    The plastics films 48 and 49 are coated in the same way as shown in the Figure 2, but without the opening 9. The plastics film 50 is coated in the same way as the ceramic disc 4 (Figure 3).
    The two inner metal rings 45 and 46 simultaneously serve as electrical connections for the adjacent conductive surfaces on both sides of the intermediate plastics film 49. Annular insulating discs 54 and 55 are located on respective sides of the two inner metal rings 45 and 46 and facing the two plastics films 48 and 50 respectively. Thin contact rings 56 and 57 are inserted between respective ones of these insulating discs 54 and 55 and the outer plastics films 48 and 50. The conductive surfaces of the plastics films 48 and 50. The conductive surfaces of the plastics films 48 and 50 facing the ionization chambers 42 and 43 respectively at their outer peripheries. The lower metal ring 47 is provided with a row of openings which are aligned parallel to its axis of symmetry.Individual electrical connections are passed through these openings to the electrode surfaces of the clamped plastics film 50 which is coated in accordance with the pattern shown in Figure 3.
    Electrical connections 58, 59, 60, 61 and 62 are guided out of this metal ring 47 in an insulated manner.
    WHAT WE CLAIM IS:
    1. A radiation detecting arrangement comprising first and second ionization chambers provided by spaced-apart, substantially parallel walls, which walls comprise first and second walls and an intermediate wall arranged them, 1 tF~Faz, the tMrt sh nber being between he firs i all and the msermediate wall and the second chamber being between the illtermedi ate wall and the second wall, in which arrangement the first wall is provided, inside the first chamber, with an electrode for the first chamber, the intermediate wall comprises or is provided with a common electrode for the first and second chambers, and the second wall is provided, inside the second chamber, with a plurality of mutually insulated electrodes for the second chamber, the mutually insulated electrodes comprising a substantially discshaped electrode, an annular arrangement of several independent electrodes substantially surrounding the substantially disc-shaped electrode, and a further electrode surrounding the said independent electrodes.
    2. A radiation detecting arrangement according to Claim 1, further comprising a first spacing member, for spacing-apart the first wall and the intermediate wall, and a second spacing member, for spacing apart the second wall and the intermediate wall.
    3. A radiation detecting arrangement acccording to Claim 2, wherein the first and second spacing members are ring-shaped.
    4. A radiation detecting arrangement according to any preceding claim, further comprising a plurality of terminals connected with respective ones of the said mutually insulated electrodes.
    5. A radiation detecting arrangement according to Claim 4, wherein the terminals extend from the remainder of the arrangement.
    6. A radiation detecting arrangement according to any preceding claim, wherein the second wall is substantially disc-shaped.
    7. A radiation detedting arrangement according to Claim 6, wherein the said substantially disc-shaped electrode is substantially central with respect to the second wall.
    8. A radiation detecting arrangement according to any preceding claim, wherein the first wall and the intermediate wall are both substantially disc-shaped.
    9. A radiation detecting arrangement according to any preceding claim, wherein the first, second, and intermediate walls are made
    of a ceramic material.
    10. A radiation detecting arrangement according to Claim 9, wherein the electrode for the first chamber and the electrodes for the second chamber comprise an electrode material coated on the insides of the first and second walls respectively.
    11. A radiation detecting arrangement according to Claim 9 or 10, wherein the common electrode for the first and second chambers comprises an electrode material coated onboth sides of the intermediate wall and on a wall of a passageway provided in the intermediate wall such that the electrode material coatings on the two sides of the intermediate wall are interconnected.
    12. A radiation detecting arrangement according to any of Claims 1 to 8, wherein the first, second, and intermediate walls comprise first, second, and third plastics films respectively.
    14. A radiation detecting arrangement according to Claim 13, wherein the electrode for the first chamber and the common electrode for the first and second chambers each comprise nickel gauze which has been applied, by an etching method, to the inside of the first plastics film and both sides of the third plastics film respectively.
    15. A radiation detecting arrangement according to Claim 13, wherein the electrode for the first chamber, the electrode for the second chamber, and the common electrode for the first and second chambers each comprise electrodes which have been evaporated on the first, second, and third plastics films respectively.
    16. A radiation detecting arrangement substantially as herein described with reference to the accompanying drawings.
GB1125478A 1978-03-21 1978-03-21 Arrangement for detecting radiation Expired GB1598962A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1125478A GB1598962A (en) 1978-03-21 1978-03-21 Arrangement for detecting radiation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1125478A GB1598962A (en) 1978-03-21 1978-03-21 Arrangement for detecting radiation

Publications (1)

Publication Number Publication Date
GB1598962A true GB1598962A (en) 1981-09-30

Family

ID=9982852

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1125478A Expired GB1598962A (en) 1978-03-21 1978-03-21 Arrangement for detecting radiation

Country Status (1)

Country Link
GB (1) GB1598962A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0063083A1 (en) * 1981-04-15 1982-10-20 Commissariat à l'Energie Atomique X rays detector
EP0071826A2 (en) * 1981-08-03 1983-02-16 Siemens Aktiengesellschaft Dose monitor chamber for electron or X-ray radiation
GB2137747A (en) * 1983-04-05 1984-10-10 Tower Hamlets Health Authority Apparatus for measuring radiation beam intensity

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0063083A1 (en) * 1981-04-15 1982-10-20 Commissariat à l'Energie Atomique X rays detector
FR2504278A1 (en) * 1981-04-15 1982-10-22 Commissariat Energie Atomique X-RAY DETECTOR
US4469947A (en) * 1981-04-15 1984-09-04 Commissariat A L'energie Atomique X-Ray detector with compensating secondary chamber
EP0071826A2 (en) * 1981-08-03 1983-02-16 Siemens Aktiengesellschaft Dose monitor chamber for electron or X-ray radiation
EP0071826A3 (en) * 1981-08-03 1983-08-03 Siemens Aktiengesellschaft Dose monitor chamber for electron or x-ray radiation
GB2137747A (en) * 1983-04-05 1984-10-10 Tower Hamlets Health Authority Apparatus for measuring radiation beam intensity

Similar Documents

Publication Publication Date Title
EP0838844B1 (en) Ionization chamber
US3942012A (en) System for monitoring the position, intensity, uniformity and directivity of a beam of ionizing radiation
US4731532A (en) Time of flight mass spectrometer using an ion reflector
US6437513B1 (en) Ionization chamber for ion beams and method for monitoring the intensity of an ion beam
US3852610A (en) Transmission ion chamber
US3838284A (en) Linear particle accelerator system having improved beam alignment and method of operation
US4131799A (en) Ionization chamber
US6100521A (en) Ion mobility spectrometer in a centripetal arrangement
US3699331A (en) Double pass coaxial cylinder analyzer with retarding spherical grids
US5326976A (en) Radiation measuring device for measuring doses from a radiotherapy aparatus
US3808441A (en) Devices for measuring the dose rate of a beam of ionising radiation
GB1598962A (en) Arrangement for detecting radiation
US3997788A (en) Device for monitoring the position, intensity, uniformity and directivity of an ionizing radiation beam
US2899582A (en) Geiger-muller detector
US4695731A (en) Ionization chamber
US3676682A (en) Absorbed ionizing radiation measuring device
US4514628A (en) Coaxial miniature magnetic spectrometer
Siemens Arrangement for detecting radiation
JPH04505828A (en) Partial pressure gauge using cold cathode ion source for leak detection in vacuum equipment
EP0040589B1 (en) A method and a device relating to a transmission ion chamber
JP7330138B2 (en) ion detector
CN113703028A (en) Medical accelerator monitoring ionization chamber
US2735953A (en) Radiation detector
US2852694A (en) Ionization chamber
US5326977A (en) Gamma-ray compensated ionization chamber

Legal Events

Date Code Title Description
PS Patent sealed
PCNP Patent ceased through non-payment of renewal fee