Device for monitoring radon exposure

• US 4,891,514 A
• Filed: 11/05/1987
• Issued: 01/02/1990
• Est. Priority Date: 11/05/1987
• Status: Expired due to Fees

• Current Assignee: GJERDRUM, DAVID, M., 559 BARRON AVENUE, PALO ALTO, CA. 94306
• Original Assignee: David M. Gjerdrum
• Inventors: Gjerdrum, David, Decuir, Joseph
• Primary Examiner(s): Howell, Janice A.
• Assistant Examiner(s): HANIG, RICHARD E
• Application Number:
  US07/117,059
• Time in Patent Office: 789 Days
• Field of Search: 250/255, 250/253, 250/370.02
• US Class Current: 250/255
• CPC Class Codes: G01T 1/178 for measuring specific activity in the presence of other radioactive substances, e.g. natural, in the air or in liquids such as rain water
• CPC Class Codes: H01L 31/02322 comprising luminescent members, e.g. fluorescent sheets upon the device
• CPC Class Codes: H01L 31/115 Devices sensitive to very short wavelength, e.g. X-rays, gamma-rays or corpuscular radiation
• CPC Class Codes: Y10S 250/02 Radon detection

Abstract

A device for monitoring radon exposure including a cube-shaped, light-tight detection chamber having approximately one-inch square sides, five sides of which each contain an integrated circuit alpha particle detector, with a sixth side having fluid intake and exhaust ports and temperature and humidity sensors. Each integrated circuit device is responsive to detect alpha particles emitted by any decaying radon-222 atoms or daughter isotopes within the detection chamber. The detected results of each integrated circuit device is communicated to an external logic system which calculates the relative level of radon concentration within the chamber and stores the information in memory, or reports the information to a variety of peripheral devices.

Claims

1. A device for monitoring radon exposure, comprising:

means forming a photon impenetrable detection chamber of a predetermined volume for continuously receiving a sampling flow of fluid from an environment being monitored;

at least one alpha particle detector being an integrated circuit disposed within said chamber, said detector having a plurality of radiation sensitive capacitance means positioned to be exposed to alpha particles within said sampling flow, said alpha particle detector being responsive to said alpha particles contacting said capacitance means and operative to develop a detection signal; and

a monitoring system for receiving a plurality of input signals including said detection signal, calculating the level of radon concentration within said environment, and generating an output signal commensurate therewith.

2. A device for monitoring radon exposure as recited in claim 1, wherein said detection chamber is shaped to restrict said sampling flow'"'"'s path to within a detectable range of said alpha particle detector.

3. A device for monitoring radon exposure as recited in claim 2, wherein said detection chamber includes a temperature sensor for monitoring the temperature of said sampling flow and developing a temperature signal for input to said monitoring system.

4. A device for monitoring radon exposure as recited in claim 3, wherein said detection chamber includes a humidity sensor for monitoring the relative humidity of said sampling flow and developing a humidity signal for input to said monitoring system.

5. A device for monitoring radon exposure as recited in claim 1, wherein said detection chamber includes means for receiving and electrically interfacing said alpha particle detector with said monitoring system, and wherein said detection chamber is formed by a dome shaped cover wherein all interior surface points of said cover are located a predetermined distance d from at least one of said capacitance means, where d is a positive integer proportional to the visibility range of alpha particles within said environment.

6. A device for monitoring radon exposure as recited in claim 5, wherein said detection chamber includes a temperature sensor for monitoring the temperature of said sampling flow and developing a temperature signal for input to said monitoring system.

7. A device for monitoring radon exposure as recited in claim 6, wherein said detection chamber includes a humidity sensor for monitoring the relative humidity of said sampling flow and developing a humidity signal for input to said monitoring system.

8. A device for monitoring radon exposure as recited in claim 1, wherein means forming said chamber is a cube having at least one alpha particle detector disposed within each of five faces of said cube and means disposed in said five faces for receiving and electrically interfacing said alpha particle detectors with said monitoring system, and wherein all interior surface points of said cube are within a distance d of at least one of said capacitance means, where d is a positive integer proportional to the visibility of alpha particles within said environment.

9. A device for monitoring radon exposure as recited in claim 8, wherein said detection chamber includes a temperature sensor for monitoring the temperature of said sampling flow and developing a temperature signal for input to said monitoring system.

10. A device for monitoring radon exposure as recited in claim 9, wherein said detection chamber includes a humidity sensor for monitoring the relative humidity of said sampling flow and developing a humidity signal for input to said monitoring system.

11. A device for monitoring radon exposure as recited in claim 1, wherein said alpha particle detector is an integrated circuit having a plurality of radiation sensitive memory cells arranged in an orthogonal array of rows and columns.

12. A device for monitoring radon exposure as recited in claim 11, wherein said memory cells are charged in either a positive or negative direction in response to interaction with said alpha particles.

13. A device for monitoring radon exposure as recited in claim 12, wherein said orthogonal array encompasses an area of at least 1.0 sq. cm.

14. A device for monitoring radon exposure as recited in claim 12, wherein said memory cells operate at a voltage charge level and refresh rate approaching the thermal noise level of said memory cells.

15. A device for monitoring radon exposure as recited in claim 1, wherein said alpha particle detector is an integrated circuit having a plurality of radiation sensitive memory cells arranged in concentric circles.

16. A device for monitoring radon exposure as recited in claim 1, further comprising:

peripheral devices for entering configuration data and displaying a calculated level of radon concentration, and

wherein said monitoring system includes

memory means for receiving and storing data signals including said detection signal and outputting selected data upon command; and

system control means for receiving detector data signals input from a plurality of said detectors, receiving said configuration data input from one or more of said peripheral devices, processing said detector data signals for input to said memory means within said data signals, processing said configuration data for input to said memory means within said data signals, receiving selected data output from said memory means upon command of said system control means, processing said selected data in a predetermined manner to generate a calculated level of radon concentration signal corresponding to the level of radon concentration within said environment, and outputting said calculated level of radon concentration signal to one or more of said peripheral devices.

17. A device for monitoring radon exposure as recited in claim 16, wherein said system control means includes:

sampling processor means for receiving said detector data signals input from said plurality of detectors and developing and outputting a processed detector data signal;

input/output processor means for receiving configuration data input from one or more of said peripheral devices, developing a configuration data signal, receiving said calculated level of radon concentration signal and outputting said calculated level of radon concentration signal to one or more of said peripheral devices; and

data processing means for receiving said processed detector data signal and said configuration data signal, outputting said processed detector data signal and said configuration data signal to said memory means, commanding and receiving said selected data from said memory means, processing said selected data in a predetermined manner to generate said calculated level of radon concentration signal corresponding to the level of radon concentration within said environment, and outputting said calculated level of radon concentration signal to said input/output processor means for communication to one or more of said peripheral devices.

18. A device for monitoring radon exposure as recited in claim 16, wherein said peripheral devices include a ventilation system which develops and outputs said configuration data signals to said system control means, receives said calculated level of radon concentration signal input from said system control means, and modifies the flow of fluid within said sampled environment in order to compensate for the level of radon concentration within said