Silicon Drift Detectors for High Resolution Radioxenon Measurements

The detection of radioactive xenon is an important component of both national and international efforts to detect nuclear explosions. Existing radioxenon detection systems have high sensitivity, but a better discrimination of Xe isotopes is desirable to better distinguish the radioxenon background created by nuclear power plants and medical isotope facilities from a nuclear explosion. Existing systems are also very complex, requiring cryocoolers to reach the operating temperatures for germanium detectors or multiple detectors for beta/gamma coincidence rejection. In the proposed effort, silicon drift detectors will be explored as a possible alternative to existing radioxenon detector systems. Silicon drift detectors are sensitive to beta radiation; have very high resolution for X-ray energies that the existing systems can not clearly distinguish; and as compact, solid state devices can be made into simpler systems. On the other hand, their detection efficiency is lower, so that the Phase I goal is a careful study of the improvements and drawbacks compared to the existing detector system. If considered feasible from the results of Phase I, a silicon drift detector prototype for radioxenon detection will be developed in Phase II. Commercial applications and other benefits: The technology to be developed in this project, if successful, will support the efforts by US agencies and the International Monitoring System established by the Comprehensive Nuclear