Neutron and gamma detector using an ionization chamber with an integrated body and moderator

Abstract

A detector for detecting neutrons and gamma radiation includes a cathode that defines an interior surface and an interior volume. A conductive neutron-capturing layer is disposed on the interior surface of the cathode and a plastic housing surrounds the cathode. A plastic lid is attached to the housing and encloses the interior volume of the cathode forming an ionization chamber, into the center of which an anode extends from the plastic lid. A working gas is disposed within the ionization chamber and a high biasing voltage is connected to the cathode. Processing electronics are coupled to the anode and process current pulses which are converted into Gaussian pulses, which are either counted as neutrons or integrated as gammas, in response to whether pulse amplitude crosses a neutron threshold. The detector according to the invention may be readily fabricated into single or multilayer detector arrays.

Description

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0001] This invention was made with Government support under Contract No. W-7405-ENG-36, awarded by the Department of Energy. The Government has certain rights in this invention.CROSS-REFERENCE TO RELATED APPLICATIONS [0002] Not Applicable INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC [0003] Not Applicable NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION [0004] Not Applicable BACKGROUND OF THE INVENTION [0005] 1. Field of the Invention [0006] This invention pertains generally to devices for detecting radiation, and more particularly to devices for detecting neutrons and gross gamma radiation. [0007] 2. Description of Related Art [0008] Neutron and gamma radiation detectors are important devices for providing large area radiation monitoring, such as in the homeland defense initiative. These detectors can be used, for example, as linear sensor arrays along highways or railways, as rings of detectors...

AI Technical Summary

Benefits of technology

[0017] Another embodiment of the invention describes a detector comprising an array of cathodes for detecting neutrons and gamma radiation. In one embodiment, half of the cathodes are upward facing and half of the cathodes are downward facing. Each cathode defines an interior surface and an interior volume. A plastic housing surrounds the cathodes. A plastic top cover is attached to the housing and encloses the interior volumes of the upward facing cathodes and a plastic bottom cover is attached to the housing opposite the top cover. The bottom cover encloses the interior volumes of the downward facing cathodes. Plural anodes extend from the top cover and the bottom cover such that each anode extends into the interior volume of each cathode. Additionally, a working gas is disposed within the interior volume of each cathode and a conductive neutron-capturing layer is disposed on the interior surface of each cathode. The proposed detectors can be configured as individual slabs, linear arrays, three-dimensional structures, arcs, tunnels, and so forth thereby providing extensive installation flexibility.

[0036] Another aspect of the invention is the use of alternating layers of moderator and Li6 foil to provide improved coupling between the moderation and capturing processes to increase efficiency.

Problems solved by technology

However, they can be extremely expensive due to complex manufacturing processes and high material costs.

Similarly, 6Li glass fiber or 10 B doped scintillation detectors are also extremely expensive, and moreover, they can exhibit significant temperature and high voltage dependencies.

Furthermore, these detectors typically rely on complicated gamma / neutron separation techniques.

In general, scintillator based neutron detectors are unable to achieve high levels of geometric efficiency at moderate cost levels.

However, the working gas in such units is permanently sealed within the detection volume and subject to the build-up of impurities.

The collecting electrode is connected to a high voltage bias source requiring that the connected sense components be able to resist these high voltages, while the high voltage is disadvantageously exposed to the surrounding environment.

Signals at the collecting electrode are also directly subject to noise from the high voltage power supply.

Furthermore, the collecting electrode is difficult to mount, induces additional detector capacitance and is susceptible to acoustic noise and vibration, wherein the proportional counter must rely on significant gas multiplication effects to provide sufficient signal-to-noise margins.

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