Adam Warniment

Compendium of TID, Neutron, Proton and Heavy Ion Testing of Satellite Electronics for Los Alamos National Laboratory

Los Alamos National Laboratory has been testing COTS electronic parts for potential use in spacecrafts. The highest risk parts were identified and tested for radiation effects.

Radiation detection and situation management by distributed sensor networks

Detection of radioactive materials in an urban environment usually requires large, portal-monitor-style radiation detectors. However, this may not be a practical solution in many transport scenarios. Alternatively, a distributed sensor network (DSN) could complement portal-style detection of radiological materials through the implementation of arrays of low cost, small heterogeneous sensors with the ability to detect the presence of radioactive materials in a moving vehicle over a specific region. In this paper, we report on the use of a heterogeneous, wireless, distributed sensor network for traffic monitoring in a field demonstration. Through wireless communications, the energy spectra from different radiation detectors are combined to improve the detection confidence. In addition, the DSN exploits other sensor technologies and algorithms to provide additional information about the vehicle, such as its speed, location, class (e.g. car, truck), and license plate number. The sensors are in-situ and data is processed in real-time at each node. Relevant information from each node is sent to a base station computer which is used to assess the movement of radioactive materials.

Thermal neutron flux characterization at aircraft altitudes with the TinMan detector

Recently, concerns have been raised about thermal neutrons causing single event effects in semiconductor devices. For example, if 10B is present in a semiconductor device, thermal neutron capture reactions can produce several MeV alpha particles. The charge that these alpha particles deposit in a sensitive volume can cause a failure. The number of single event effects from thermal neutrons is the product of the thermal neutron intensity times the thermal neutron failure cross section. This paper presents the status of the thermal neutron flux measurements with the TinMan thermal neutron detector at aircraft altitudes. Thermal neutrons are produced in an airplane when high energy-neutrons, created by the interaction of cosmic rays in the atmosphere, are thermalized in the fuel, the passengers and the airplane itself. Therefore, they are very environment dependent. Airplanes are a particular concern because at aircraft altitudes, the cosmic-ray neutron flux is approximately 300 times the sea-level neutron flux. Therefore, the understanding of the thermal neutron intensity at aircraft altitude is critical for understanding the risks of thermal neutrons to avionics systems. We have designed and built TinMan to measure the thermal neutron environment in prototypical aircraft. The TinMan detector consists of two 3He ionization chambers. One of the 3He ionization chamber is wrapped in a thin layer of cadmium. Because the cadmium shielding attenuates the thermal neutrons, the difference in count rates between these two detectors reflects the number of thermal neutrons detected. We have calibrated the detector prior to the flight, acquired data during several flights in a NASA ER-2 airplane and plan to fly the detector on other NASA experimental aircrafts, which are more prototypical of a large commercial airplane. This paper will present the status of these measurements.