SPACE CHARGE DOSIMETERS FOR EXTREMELY LOW POWER MEASUREMENTS OF RADIATION IN SHIPPING CONTAINERS

• US 20090212226A1
• Filed: 03/18/2009
• Published: 08/27/2009
• Est. Priority Date: 05/06/2004
• Status: Active Grant

• Current Assignee: UT-Battelle LLC
• Original Assignee: UT-Battelle LLC
• Inventors: Hanson, Gregory R., Buckner, Mark A., Bryan, William L., Britton, Charles L. JR.
• Granted Patent: US 7,932,828 B2
• Time in Patent Office: Days
• US Class Current: 250/370.70
• CPC Class Codes: G06Q 10/08 Logistics, e.g. warehousing, loading or distribution; Inventory or stock management
• CPC Class Codes: G08B 13/2462 Asset location systems combined with EAS inventory, tracking, logistic G06Q10/00; entrance control systems G07C9/00
• CPC Class Codes: G08B 21/12 responsive to undesired emission of substances, e.g. pollution alarms
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

Methods and apparatus are described for space charge dosimeters for extremely low power measurements of radiation in shipping containers. A method includes insitu polling a suite of passive integrating ionizing radiation sensors including reading-out dosimetric data from a first passive integrating ionizing radiation sensor and a second passive integrating ionizing radiation sensor, where the first passive integrating ionizing radiation sensor and the second passive integrating ionizing radiation sensor remain situated where the dosimetric data was integrated while reading-out. Another method includes arranging a plurality of ionizing radiation sensors in a spatially dispersed array; determining a relative position of each of the plurality of ionizing radiation sensors to define a volume of interest; collecting ionizing radiation data from at least a subset of the plurality of ionizing radiation sensors; and triggering an alarm condition when a dose level of an ionizing radiation source is calculated to exceed a threshold.

Claims

1. A method, comprising insitu polling a suite of passive integrating ionizing radiation sensors including reading-out dosimetric data from a first passive integrating ionizing radiation sensor and a second passive integrating ionizing radiation sensor,

wherein the first passive integrating ionizing radiation sensor and the second passive integrating ionizing radiation sensor remain situated where the dosimetric data was integrated while reading-out dosimetric data and

wherein the first passive integrating radiation sensor and the second passive integrating radiation sensor are connected to read-out circuits presenting extremely high impedance while in a passive integration mode and while in an active read-out mode, without destruction of integrated dosimetric data allowing continuous integration of ionizing radiation to a maximum extent of the first passive integrating ionizing radiation sensor and the second passive integrating ionizing radiation sensor.

2. The apparatus of claim 1, wherein the read-out circuits present impedance of from approximately 10¹¹ ohms to approximately 10¹⁵ ohms.

3. A method, comprising insitu polling a suite of passive integrating ionizing radiation sensors including reading-out dosimetric data from a first passive integrating ionizing radiation sensor and a second passive integrating ionizing radiation sensor,

wherein the first passive integrating ionizing radiation sensor and the second passive integrating ionizing radiation sensor remain situated where the dosimetric data was integrated while reading-out and

wherein the first passive integrating radiation sensor and the second passive integrating radiation sensor are connected to read-out circuits presenting extremely high impedance while in passive integration mode and during active read-out of dosimetric data without destruction of integrated dosimetric data allowing continuous integration of ionizing radiation to the maximum extent of the sensors and upon sensing the attainment of maximum integration limits, readout circuits will reset passive integrating radiation sensors and accumulate in a non-volatile manner the number of sensor reset cycles.

4. The apparatus of claim 3, wherein the read-out circuits present impedance of from approximately 10¹¹ ohms to approximately 10¹⁵ ohms.

5. An apparatus comprising:

a first passive integrating ionizing radiation sensor;

a second passive integrating ionizing radiation sensor;

a read-out circuit coupled to both the first passive integrating ionizing radiation sensor and the second passive integrating ionizing radiation sensor, the read-out circuit presenting an extremely high impedance to both the first passive integrating ionizing radiation sensor and the second passive integrating ionizing radiation sensor both while the read-out circuit is in a passive integration mode and while the read-out circuit is in an active read-out mode; and

a communication circuit coupled to the read-out circuit,

wherein read-out dosimetric data from both the first passive integrating radiation sensor and the second passive integrating radiation sensor is presented to the communications circuit.

6. The apparatus of claim 5, wherein at least one sensor selected from the group consisting of the first passive integrating ionizing radiation sensor and the second passive integrating ionizing radiation sensor includes a thick oxide insulated gate field effect transistor space charge dosimeter.

7. The apparatus of claim 5, wherein the read-out circuits present impedance of from approximately 10¹¹ ohms to approximately 10¹⁵ ohms.

8. An apparatus, comprising:

a thick oxide dosimeter; and

a readout circuit coupled to the thick oxide dosimeter,

wherein both the thick oxide dosimeter and the readout circuit are constructed on a single high impedance and low leakage substrate.

9. The apparatus of claim 8, wherein the thick oxide dosimeter includes a thick oxide insulated gate field effect transistor space charge dosimeter.

10. The apparatus of claim 8, wherein the single high impedance and low leakage substrate includes at least one construction selected from the group consisting of silicon on sapphire, silicon on insulator and transmutated high resistivity silicon.

11. The apparatus of claim 8, wherein the read-out circuits present impedance of from approximately 10¹¹ ohms to approximately 10¹⁵ ohms.