Projects
The RDNS group's 80 expert staff have specific recent experience with a variety of technical fields and have been involved in a variety of projects.
Majorana Project
Researchers in the RDNS group have joined an international quest to measure the effective mass of the electron neutrino by developing a unique array of germanium detectors that would enable sensitive double-beta decay experiments in an unprecedented manner. Through double-beta decay, scientists hope to detect extremely rare decays of the isotope 76Ge and the effective Majorana mass of the electron neutrino.
Under the auspices of the Majorana Collaboration, scientists from Pacific Northwest National Laboratory (PNNL), Brown, New Mexico State, and Osaka universities; the universities of Chicago, South Carolina, Tennessee, and Washington, the Institute for Theoretical and Experimental Physics in Russia, the Joint Institute for Nuclear Research, Dubna, Russia; the Triangle Universities Nuclear Laboratory; and Lawrence Livermore National Laboratory; Los Alamos National Laboratory; Oak Ridge National Laboratory; and Lawrence Berkeley National Laboratory are aiming to build an unprecedented detector system with approximately 210 individual germanium detectors. The Majorana Collaboration approach stands out for its specially designed detectors with unique low-background materials and the underground location required to reduce cosmic-ray background interference.
Using bulk electroforming, PNNL scientists have built copper components with high radiopurity, resulting in lower background levels for the measurements. They packaged germanium crystals enriched in 76Ge into the copper components, and then instrumented the system. The proof-of-concept detectors will allow scientists to validate the modeled background performance of the final detector array.
For more information, see the Majorana website.
Radiation Portal Monitors
The Radiation Detection & Nuclear Science group's radiological science expertise is contributing to the security of the nation through the Radiation Portal Monitor Project. As requested by the Department of Homeland Security's U.S. Customs and Border Protection, PNNL is leading the effort to adapt and deploy radiation portal monitors and associated radiation-detection equipment at more than 370 land and rail border crossings, mail facilities and express consignment courier facilities, seaports, and airports across the nation.
Since 2002, many technologies have bee, and continue to be, evaluated and adapted by our staff for radiation interdiction purposes under this project. Some of these technologies include the following:
- Radiation portal monitor: Constructed using polyvinyl toluene gamma-ray detection material and 3He neutron detectors, these passive radiation-detection systems emit no radiation themselves. Used primarily at mail and package-handling facilities, land crossings, seaport terminals, and other vehicle screening venues, these systems are often placed on both sides of a monitored lane, allowing the vehicle to pass through. The system comprises two or more detector panels that detect both gamma-ray and neutron radiation.
- Mobile radiation portal monitor: This portable radiation-detection device is mounted to a truck chassis and is designed to scan cargo containers on the ground or on trucks, especially at seaports.
- Remotely operated radiation portal monitor: This technology integrates radiation portal monitors with commercial remote surveillance technology to provide a cost-effective solution for monitoring sites where the physical presence of staff is difficult.
- Spectroscopic portal monitor: Using sodium-iodide detectors, this system allows positive identification of radioactive isotopes for resolution of alarms, and improved rejection of naturally occurring radioactive material (found in cargo such as kitty litter, tile, and fertilizer).
- Analysis algorithms: Radiation portal monitors incorporate various analysis methods for enhanced detection of radiation sources of concern. One of these methods is energy windowing, an algorithm that is used to differentiate harmful, illicit materials (plutonium, highly enriched uranium) from naturally occurring radioactive material. Significant work is being performed to model and simulate detector response to various radiation source configurations in order to predict the performance of the systems under a range of deployed conditions.
- Visual identification system:Cameras are integrated with the radiation portal monitor to capture images of vehicles that pass through the system-allowing accurate, rapid identification of alarming vehicles.
- Port Radiation, Interdiction, Detection, and Evaluation (PRIDE) system: PRIDE is software that integrates the radiation portal monitor with a wide area network and a database that allows Customs to store and retrieve data obtained from all radiation portal monitors deployed across the nation. This database provides a tool that allows troubleshooting and resolution of equipment problems remotely.
Timed Neutron Detector
The Timed Neutron Detector (TND) developed by researchers in the RDNS group at PNNL appears similar to a metal detector, yet it applies physics to discover signs of a landmine's presence. Specifically, the system detects hydrogen, which is present in the casings and explosives found in plastic and metal landmines.
The TND system consists of a neutron source about the size of a personal pager and a detector built into a man-portable system that can be swept over the ground, much like a metal detector. The radiation exposure to the operator from this source is smaller than the variation in natural radiation exposure across the United States, and smaller than the occupational radiation exposure experienced by an airline pilot.