Technique for Low Level Radiation Detection in High Background Environments with Correlation Filtering
Reference number: STC-PS-0970
Inventor(s): A. Hecht
For more information, contact: Erin M. Beaumont (505-272-7912)
or Jovan Heusser, M.B.A. (505-272-7908)
Patent(s)
Application(s) pending
Background
In radiation detection and spectroscopy, background noise can easily disguise weak signals. For a weak source, signal can easily be dismissed as random fluctuation. The need for inexpensive and novel methods for resolving weak signals from background noise is highly desirable for many applications. It can be used for nuclear source detection and localization for nonproliferation, environmental remediation, and medical imaging.
There exist many techniques to reduce noise from radiation detectors, such as shielding and Compton scatter vetoing. Equipment helps, such as using higher resolution detectors so the signal spectral peak is sharper and more easily discerned. There are also many methods to treat the signal to reduce background contamination, such as using time coincidence to correlate data from specific decay events. Technology does not stand still and novel techniques can be a great benefit.
Technology
The presented technology addresses a novel technique to extract radiation signals from very low signal-to-noise environments. Current approaches to increasing detected signal strength are to increase detection efficiency by increasing detector size or using higher efficiency materials. However, increasing detector efficiency also increases the collection of background noise, with true signals still being hidden in background noise. This presented technique allows us to solve this problem by filtering out more of the noise using a novel approach to correlating detector data.
Applications/Advantages
This presented increase in sensitivity means a great savings in cost. There are many techniques to pull radiation signals from noise. For example, the sharper spectral lines of more expensive detectors like liquid nitrogen cooled germanium crystals allows weak peaks to be discerned from background. With the presented technique, less expensive detectors can be used with a high noise rejection. This higher sensitivity approach to detection could easily save millions of dollars in extended detection systems.
The higher sensitivity also reduces the time for detection and identification of radioactive materials, which is a benefit in reducing costs and, for biological imaging, reducing dose. There are many applications which can benefit from this technique of extracting weak radiation signals from background noise. Examples are listed below.
1. Nuclear Nonproliferation:
For nuclear nonproliferation, detectors are set up to find special nuclear materials passing through international borders and ports. Special nuclear materials such as uranium and plutonium are of particular interest, but these emit low energy gamma rays which are easy to shield. Detectors with high efficiency for those low energies are needed to help in identifying those materials, but are susceptible to the large spectral background at low energies. The new technique can be used to allow us to effectively filter out the background using inexpensive detectors. Filtering out the noise allows an increase in efficiency of the detector used, increasing the sensitivity to the true signals. Many inexpensive detectors can be used in detection rather than a few expensive, high resolution detectors. This greatly increases total efficiency while greatly lowering the cost.
The increased detection sensitivity also lowers the time that cargo must be surveyed. This reduces bottlenecks and allows more cargo to be inspected at busy ports and border stations.
2. Environmental remediation:
Radioactive materials in environments being cleaned up may be below other material, causing shielding of the sources. The low signal to detectors can be lost in the noise and statistics may not be sufficient for detection without a long dwell time. The proposed technique can pull weak signals from background, greatly increasing the speed with which an area is surveyed for radioactive materials. Saving time in a large clean up can save considerable expense.
3. Medical Imaging:
An effectively higher sensitivity to true signals coming from source activity can reduce the radiation needed for detection and imaging applications. This could serve to reduce the amount of radioactive source material used for medical imaging, reducing the dose to patient.
Summary:
The technology provides an inexpensive way to extract signal from noise in low signal-to-noise environments. The technology:
•can allow inexpensive detectors to be used with high sensitivity and good background rejection.
•can have applications in finding materials in environmental remediation
•can have extensive applications in nuclear material control and accountability
•can have applications in finding hidden nuclear materials such as at border crossing and ports
•can be implemented with very flexible design
•can provide inexpensive radiation detection technology, and allow hardier detectors in more difficult environments
•can be used in some types of medical imaging, with the higher sensitivity reducing dose of radioactive material given to patients
Keywords
Medical Imaging, Nuclear Detection
Related Categories
Environmental Engineering and Hazardous/Radioactive Waste Technologies
