Identifying and quantifying the presence of alpha radiation and specific gaseous molecules present in air samples

• US 5,153,520 A
• Filed: 07/25/1990
• Issued: 10/06/1992
• Est. Priority Date: 10/03/1984
• Status: Expired due to Fees

• Current Assignee: James R. Brown
• Original Assignee: Robert F. Dumbeck
• Inventors: Dumbeck, Robert F.
• Primary Examiner(s): Wieder, Kenneth A.
• Application Number:
  US07/557,098
• Time in Patent Office: 804 Days
• Field of Search: 324/469, 324/464, 324/71.1, 324/459, 324/465, 324/466, 324/467, 324/468, 250/384, 250/381, 250/382, 250/253, 73/23.21, 73/23.35
• US Class Current: 324/469
• CPC Class Codes: G01N 33/0024 a chemical reaction taking place or a gas being eliminated in one or more channels
• CPC Class Codes: G01N 33/0055 Radionuclides
• CPC Class Codes: G08B 17/117 by using a detection device for specific gases, e.g. combustion products, produced by the fire G08B17/103, G08B17/11 take precedence

Abstract

Means and methods of detecting particular particles in an air stream at very low concentration levels and identifying the particles and magnitude of concentration are afforded. Thus, a particle detector cell has a source of ionizing radiation of constant magnitude, an anode and cathode for moving ions through a radiation activity region and a detector electrode for capturing and measuring free electrons as a dynamic signal indication of the presence of particular particles in the activity region. Particular gas molecules are identified by their fingerprint, namely a spectral response to resonating frequency of electrons orbiting in their molecular structure. The magnitude of free electrons detected determine the concentration of the particles present in air. The output may be recorded on a strip chart for identification and quantification or may be logged in a digital computer. The computer may organize a frequency scanning procedure correlated with dynamic free electron activity for digital storage and recall, and for comparison with spectrum tables for identification of molecules present in an air stream. The detector is very sensitive to low concentration levels of particles such as a few microcuries of alpha particles per liter of air, with equivalent detection of particular gas molecules which can be ionized in the presence of r-f fingerprinting frequencies.

Claims

1. A radiation detection system for detecting and quantizing the presence of unknown molecular particles in air at atmospheric pressures, comprising in combination:

a cell housing having an entry way for introducing a stream of air into the housing at substantially atmospheric pressure;

radiation means for introducing external radiation into the housing;

a set of electrodes comprising an anode, a cathode and a detector electrode for monitoring free electrons within the housing;

a calibrated alpha radiation emission standard source producing an ionization within the housing that induces free electrons at the detector electrode;

means for interacting the stream of air and external radiation and the alpha radiation induced ionization in an alpha radiation activity region within the housing to dynamically affect molecular particle activity in the stream of air to produce emission of free electrons and detection of the free electrons at the detector electrode, and means for identifying the presence of specific particles introduced within the housing through said entryway by analysis of dynamic signals detected at said detector electrode in response to the external radiation introduced into the housing.

2. The detection system of claim 1 wherein said unknown molecular particles comprise a concentration of unknown gas molecules carried in the air stream, said means for introducing external radiation) further comprises means for producing radio frequency radiation in the housing of a variable frequency range for inducing an identifying resonant reaction in particular gaseous molecules, and said means for identifying the presence of particles further comprises means for comparing the magnitude of the dynamic response at the detector electrode with an identifying resonant frequency to determine the presence of specific gaseous molecule particles present in the air stream.

3. The detection system of claim 2 further comprising calibrated air pumping means for determining the air flow through the cell housing, and means for converting the detector electrode dynamic signals into a measurement of concentration per unit air of measured particles.

4. The detection system of claim 2 further comprising a strip recorder responding to a magnitude of electrons detected at said detector electrode in the presence of r-f radiation of a known frequency for quantitatively measuring the magnitude of concentration of said specific gaseous molecule particles in the air stream.

5. The detection system of claim 1 wherein said radiation means for introducing external radiation further comprises an r-f antenna within said housing and means for radiating from the antenna a frequency in the range of one to twenty gigaHz.

6. The detection system of claim 5 further comprising an r-f pickup probe within the housing in said alpha radiation activity region for detection of r-f activity.

7. The detection system of claim 5 further comprising a variable frequency oscillator coupled to the antenna for producing a frequency within said range, means for scanning the frequency through a frequency range including that known to identify particular gas molecules by their resonance response, and means coupled to said pickup probe for determining r-f response in the region of the alpha particle activity during a period of scanning the frequency range.

8. The detection system of claim 7 further comprising means for converting detected responses at said detector electrode and said r-f probe into digital signals.

9. The detection system of claim 8 further comprising a digital computer for analyzing the digital signals.

10. The detection system of claim 9 further comprising frequency scanning control means for scanning said oscillator through said frequency range, and digital computer control means for correlating detected responses within said housing with the frequency of the oscillator.

11. The detection system of claim 1 further comprising, means locating said entry way to pass through the anode electrode, a range control electrode located between said detector electrode and the entry way in said housing, and range control means for varying the potential on the range control electrode to reduce the detection sensitivity of the detector electrode.

12. The method of identifying unknown particles and their concentration in an air stream at substantially atmospheric pressure comprising the steps of:

creating a alpha radiation activity region in the air stream of calibrated constant magnitude,

introducing the unknown particles into said alpha radiation activity region,

providing anode and cathode electrode means for monitoring the alpha radiation activity,

interspersing an electron detecting electrode in the radiation activity region to determine the presence of free electrons,

dynamically measuring free electron activity changes in the alpha radiation activity region at the detecting electrode in the presence of the unknown particles to determine the magnitude of the unknown particles,

introducing r-f radiation into the alpha radiation activity region,

and monitoring r-f radiation dynamic changes in the presence of particular gas molecules in the air stream entering the alpha radiation activity region.

13. The method of determining the identity of particular gaseous molecules in air at substantially atmospheric pressure comprising the steps of ionizing the molecules by excitation with r-f radiation to which those molecules resonate while in a region of alpha radiation activity of constant magnitude, and determining the dynamic effect of electron activity in the region to establish a magnitude of concentration of the molecules.

14. A particle detector cell comprising in combination, a source of ionizing radiation of constant magnitude, an anode and cathode for moving ions through a radiation activity region, a detector electrode located in said region to capture and measure free electrons as a dynamic indication of the presence of particular particles in the activity region that affect the ionization magnitude, and r-f radiation disbursing means in said activity region for existing particular gas particles into ionization with a radiation frequency related to orbital resonance in the gas particles.

15. A particle detector cell comprising in combination, a source of ionizing radiation of constant magnitude, an anode and cathode for moving ions through a radiation activity region, a detector electrode located in said region to capture and measure free electrons as a dynamic indication of the presence of particular particles in the activity region that affect the ionization magnitude, an air stream access path into said cell, and an electrode dispersed to inhibit the passing of charged particles into said air stream path thereby to decrease the sensitivity of detection of the cell to said free elections.