Ionising radiation detector

• US 8,810,416 B2
• Filed: 11/04/2010
• Issued: 08/19/2014
• Est. Priority Date: 07/12/2003
• Status: Expired due to Fees

• Current Assignee: Radiation Watch Limited
• Original Assignee: Radiation Watch Limited
• Inventors: Doughty, Peter Trevor, Anderson, Michael John, Prendergast, David Jeremy, Benson, Ian
• Primary Examiner(s): Bugg, George
• Assistant Examiner(s): Akhter, Sharmin
• Application Number:
  US12/939,321
• Publication Number:
  US 20110121980A1
• Time in Patent Office: 1,384 Days
• Field of Search: 34053926-53929, 340577-583, 340/600, 340/629, 340/632, 340/636.1, 340/636.19, 250/370.01, 250/370.07, 250/385.1, 250/395, 250/472.1
• US Class Current: 340/600
• CPC Class Codes: G01T 1/026 Semiconductor dose-rate meters
• CPC Class Codes: G01T 1/247 Detector read-out circuitry for processing gain or off-set correction H04N
• CPC Class Codes: G01T 1/366 with semi-conductor detectors see provisionally also G01T1/36
• CPC Class Codes: H01L 27/14634 Assemblies, i.e. Hybrid structures
• CPC Class Codes: H01L 27/14665 Imagers using a photoconductor layer
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof
• CPC Class Codes: H04N 25/771 comprising storage means other than floating diffusion
• CPC Class Codes: H04N 25/79 Arrangements of circuitry being divided between different or multiple substrates, chips or circuit boards, e.g. stacked image sensors

Abstract

An assembly (13) for monitoring ionising radiation comprises a detector substrate (2) for generating electronic charge responsive to incident ionising radiation, the detector substrate (2) having an array of ionising radiation sense volumes (12) formed in it. A circuit substrate (14) supporting an array of read-out circuits (16) corresponding to the array of sense volumes is mechanically and electrically coupled to the detector substrate (14). Each of the read-out circuits (16) is switchable between first and second charge integration modes for receiving charge from a corresponding sense volume. A charge integration circuit (30) is configured in the first charge integration mode to integrate charge corresponding to sensing of a single ionising radiation detection event in a corresponding sense volume and in the second charge integrating mode to integrate charge corresponding to sensing a plurality of ionising radiation detection events in the corresponding sense volume.

Claims

1. An assembly for monitoring radiation, comprising:

a detector substrate for generating electronic charge responsive to incident radiation, said detector substrate configured to form an array of ionising radiation sense volumes; and

a circuit substrate supporting an array of read-out circuits corresponding to said sense volumes;

wherein

a first of said read-out circuits includes photon counting circuitry electronically configurable to respond to a current pulse corresponding to the detection in a corresponding first radiation sense volume of ionising radiation in a first energy range in a first detection period to increment a first count value, and a second of said read-out circuits including photon counting circuitry electronically configurable to respond to a current pulse corresponding to the detection in a corresponding second radiation sense volume of ionising radiation in a second energy range in a second detection period to increment a second count value;

wherein said first detection period corresponds to a first frame read-out cycle in which said photon counting circuitry is operative to increment said first count value responsive to detection of ionising radiation in a first window corresponding to said first energy range, and said second detection period corresponds to a second frame read-out cycle in which said photon counting circuitry is operative to increment said second count value responsive to detection of ionising radiation in a second window corresponding to said second energy range, wherein said first and second read-out circuits are operative to read-out frames successively in progressive scanning of successive frames and wherein said second energy range is different from said first energy range;

wherein said photon counting circuitry comprises threshold circuitry including a lower current threshold level and an upper current threshold level for defining one or other of said first energy range and said second energy range, said threshold circuitry configured to output a count pulse to said photon counting circuitry responsive to a current pulse having an amplitude within the range defined by said upper current threshold level and lower current threshold level, and wherein said threshold circuitry is operative to adjust said lower current threshold level and said upper current threshold level for each successive read-out cycle such that, in progressive scanning of successive frames, said second window is an increment in the energy spectrum on the previous window.

3. An assembly according to claim 1, wherein said detector substrate comprises semi-conductor material.

5. An assembly according to claim 1, wherein said circuit substrate comprises semi-conductor material.

7. An assembly according to claim 1, wherein said sense volumes comprise a cross-section area in the range between 20 μ

m×

20 μ

m×

0.25 mm to 2 mm×

2 mm×

5 mm.

9. The assembly of claim 1, further comprising a semi-conductor detector substrate crystal configured with a plurality of ionising radiation sense volumes, said detector substrate crystal supporting conductive material across a first surface thereof and an array of conductive pads disposed across a second surface thereof opposing said first surface thereby defining said plurality of sense volumes.

11. An assembly according to claim 1, wherein the assembly is part of an ionising radiation monitoring device in a radiation monitoring network, the network further comprising:

a communications unit for communicating at least radiation data corresponding to radiation sensed by said device over a communications network; and

a control station configured to receive said radiation data from said device.

2. An assembly for monitoring radiation, comprising:

a detector substrate for generating electronic charge responsive to incident radiation, said detector substrate configured to form an array of ionising radiation sense volumes; and

a circuit substrate supporting an array of read-out circuits corresponding to said sense volumes;

wherein

said read-out circuits comprise photon counting circuitry electronically configurable to respond to a current pulse corresponding to the detection in said detector substrate of ionising radiation in a first energy range in a first detection period to increment a first count value or to respond to a current pulse corresponding to the detection in said detector substrate of ionising radiation in a second energy range to increment a second count value in a second detection period;

wherein said first detection period corresponds to a first frame read-out cycle in which said photon counting circuitry is operative to increment said first count value responsive to detection of ionising radiation in a first window corresponding to said first energy range, and said second detection period corresponds to a second frame read-out cycle in which said photon counting circuitry is operative to increment said second count value responsive to detection of ionising radiation in a second window corresponding to said second energy range, wherein said first and second read-out circuits are operative to read-out frames successively in progressive scanning of successive frames and wherein said second energy range is different from said first energy range ;

wherein said photon counting circuitry comprises threshold circuitry including a lower current threshold level and an upper current threshold level for defining one or other of said first energy range and said second energy range, said threshold circuitry configured to output a count pulse to said photon-counting circuitry responsive to a current pulse having an amplitude within the range defined by said upper current threshold level and lower current threshold level, and wherein said threshold circuitry is operative to adjust said lower current threshold level and said upper current threshold level for each successive read-out cycle such that, in progressive scanning of successive frames, said second window is an increment in the energy spectrum on the previous window.

4. An assembly according to claim 2, wherein said detector substrate comprises semi-conductor material.

6. An assembly according to claim 2, wherein said circuit substrate comprises semi-conductor material.

8. An assembly according to claim 2, wherein said sense volumes comprise a cross-section area in the range between 20 μ

m×

20 μ

m×

0.25 mm to 2 mm×

2 mm×

5 mm.

10. The assembly of claim 2, further comprising a semi-conductor detector substrate crystal configured with a plurality of ionising radiation sense volumes, said detector substrate crystal supporting conductive material across a first surface thereof and an array of conductive pads disposed across a second surface thereof opposing said first surface thereby defining said plurality of sense volumes.

12. An assembly according to claim 2, wherein the assembly is part of an ionising radiation monitoring device in a radiation monitoring network, the network further comprising:

a communications unit for communicating at least radiation data corresponding to radiation sensed by said device over a communications network; and

a control station configured to receive said radiation data from said device.

13. A method for monitoring radiation, the method comprising:

configuring photon-counting circuitry to respond to a current pulse corresponding to the detection of ionising radiation in a first energy range in a first detection period to increment a first count value, wherein said first detection period corresponds to a first frame read-out cycle in which said photon counting circuitry is operative to increment said first count value responsive to detection of ionising radiation in a first window corresponding to said first energy range;

configuring said photon-counting circuitry to respond to a current pulse corresponding to detection of ionising radiation in said second energy range in a second detection period to increment a second count value, wherein said second detection period corresponds to a second frame read-out cycle in which said photon counting circuitry is operative to increment said second count value responsive to detection of ionising radiation in a second window corresponding to said second energy range;

configuring threshold circuitry to define a lower current threshold level and an upper current threshold level for defining one or other of said first energy range and said second energy range;

outputting a count pulse to said photon-counting circuitry responsive to a current pulse having an amplitude within the range defined by said upper current threshold level and lower current threshold level;

adjusting said lower current threshold level and said upper current threshold level for each successive read-out cycle such that, in progressive scanning of successive frames, said second window is an increment in the energy spectrum on the previous window;

reading said count values from each of said photon-counting circuitry configured for said first or second energy ranges successively in progressive scanning of successive frames.

14. A method according to claim 13, the method further comprising:

receiving spectroscopic data representative of the energy of sensed radiation from a remote ionising radiation sensor over a communications network; and

automatically determining from said spectroscopic data if said radiation is hazardous and issuing a warning signal if said radiation is hazardous.