Thin Gap Chamber Neutron Detectors

Patent metadata

Field	Value
Publication number	US-2016018538-A1
Application number	US-201514591983-A
Country	US
Kind code	A1
Filing date	Jan 8, 2015
Priority date	Jan 8, 2014
Publication date	Jan 21, 2016
Grant date	—

Abstract

The present specification describes systems and methods for the simultaneous detection of radioactive materials such as neutrons, muons and gamma rays based on thin gap chamber technology. A thin-gap chamber (TGC) is disclosed having a thermal neutron absorber material, such as 10 B 4 C or 10 B 8 C, which interacts with neutrons to emit heavy particles. The heavy particles, in turn, interact with the gas present in chamber to produce ionization that is converted into a measurable signal. The TGC is embedded in a neutron moderating medium. The detector systems are fabricated from commercially available construction materials and are easy to manufacture at a reasonable cost when compared to conventional He-3 neutron detector systems.

First claim

We claim:

1 . A system for the detection of neutrons, comprising:
a plurality of thin gap chambers comprising a thermal neutron absorber material, wherein said thermal neutron absorber material is adapted to function as a cathode and is configured to interact with slow neutrons to emit charged particles and a gaseous substance positioned to interact with said charged particles to produce a signal; a moderator material positioned proximate to the thin gap chambers to decrease a speed of fast neutrons; and an electronics system to process said signal.

2 . The system of claim 1 , wherein the thermal neutron absorber material comprises a 6 Li containing material.

3 . The system of claim 1 , wherein the thermal neutron absorber material comprises at least one of 10 B 4 C or 10 B 8 C.

4 . The system of claim 3 , wherein the thermal neutron absorber material has a thickness of approximately 1 μm.

5 . The system of claim 1 , wherein the moderator is polyethylene.

6 . The system of claim 1 , wherein multiple thin gap chambers are stacked to increase detection efficiency.

7 . The system of claim 1 , wherein a thickness of the moderator material and/or thickness of the thermal neutron absorber material are adjusted to modify the response time of the detector.

8 . The system of claim 7 , wherein the thickness of the moderator material is in a range of 0.2 to 2 cm.

9 . The system of claim 7 , wherein, for passive detection applications, the thickness of the moderator material used is approximately 1 cm.

10 . The system of claim 1 , wherein a plastic scintillator material is positioned on a front portion of detector to detect gamma rays.

11 . The system of claim 10 , wherein said plastic scintillator comprises polyvinyl toluene (PVT).

12 . The system of claim 1 , wherein a plurality of thin gap chambers are configured to simultaneously detect muons to determine a presence of high atomic-number materials and neutrons.

13 . The system of claim 1 , wherein said gaseous substance comprises a mixture of n-pentane and CO 2 .

14 . A system for simultaneous detection of scattered muons, to detect a presence of high-Z materials, and neutrons emitted from radioactive materials concealed in a cargo comprising:
at least two thin gap chambers placed above the cargo and at least two thin gap chambers placed below the cargo wherein each of said thin gap chambers contains a gaseous substance and comprises an array of wires that is configured to be an anode and at least one layer of thermal neutron absorber material is configured to be a cathode; a moderator material positioned proximate each thin gap chamber to decrease a speed of incoming fast neutrons; and a controller to detect and process signals, generated in said array or wires, representative of neutron and muon radiation intensity.

15 . The system according to claim 14 , where a gamma ray detector is positioned facing the cargo such that gamma rays can be simultaneously detected along with neutrons and muons.

16 . The system according to claim 14 , wherein said thermal neutron absorber material comprises at least one of boron carbide such as in form of 10 B 4 C or 10 B 8 C, or 6 Li.

17 . The system according to claim 14 , wherein, for muon detection, the two thin gap chambers above the cargo detect a first coordinate and an angle of incidence of incoming muons and the two thin gap chambers below the cargo detect a second coordinate and an angle of exit of the muons.

18 . The system according to claim 14 , wherein muon particles are detected based on recording of signals in two or more thin gap chambers and neutrons are detected based on recording of signals in only one thin gap chamber.

19 . A system for simultaneous detection of scattered muons, a presence of high-Z materials, gamma rays and neutrons emitted from radioactive materials concealed in a cargo comprising:
at least two thin gap chambers placed above the cargo and at least two thin gap chambers placed below the cargo wherein each of said thin gap chambers is filled with a gaseous substance and comprises an array of wires that function as an anode and at least one layer of thermal neutron absorber material that functions as a cathode; a moderator material positioned near each thin gap chamber to slow down the incoming fast neutrons; a gamma-ray detector placed facing the cargo; and a controller to detect signals representative of neutron, gamma and muon radiation strength.

Assignees

• Rapiscan Systems Inc

Inventors

• Bendahan Joseph
• King Michael

Classifications

• G01T3/008 Primary

  using an ionisation chamber filled with a gas, liquid or solid, e.g. frozen liquid, dielectric (G01T3/006 takes precedence) · CPC title

• G01T3/08 Primary

  with semiconductor detectors · CPC title