Tensioned Metastable Fluid Detectors for active interrogation of Special Nuclear Materials

This paper describes the first step in developing a Tensioned Metastable Fluid Detector (TMFD) based method for active detection of Special Nuclear Materials (SNMs). One of the greatest difficulties in detection of SNMs by active interrogation is the task of distinguishing between the probing particles and the secondary particles that indicate the presence of SNMs. The TMFD´s selective insensitivity and gamma photon blindness features are advantageous for alleviating this problem. The working principle of the TMFD is discussed along with its applications for security. The experimental work to date involving detection of small quantities of uranium with conventional detectors is discussed along with results of fission neutron detection. Statistically significant detection was obtained within 5 minutes of counting to ascertain and measure conclusive evidence for the presence of a 25 g sample of uranium containing < 0.1g of ²³⁵U. Results of simulations of the TMFD experiments to come are presented, and the road map for developing the TMFD-based active interrogation detection system is laid out.