The “Radiation Continuity Checker”, an instrument for monitoring nuclear disarmament treaty compliance

We describe the design and construction of an instrument designed to monitor compliance with future arms control treaties. By monitoring changes in the gamma-ray spectrum emitted by a stored nuclear weapon, our device is able to sense perturbations in the contents of a weapon storage container that would indicate treaty non-compliance. Our instrument (dubbed the Radiation Continuity Checker or RCC) is designed to detect significant perturbations in the gamma-ray spectra (indicative of tampering) while storing no classified information about the weapon, and having a negligible “false alarm rate”. In this paper we describe the technical details of two prototype instruments and describe the strategies we have adopted to perform signal processing in these instruments. Our first instrument prototype uses a scintillation spectrometer and a massive tungsten alloy collimator to reject the gamma-ray background. Our second prototype instrument makes use of an active collimation scheme employing a multiple detector Compton scatter approach to reject background radiation. The signal processing method we employ uses linear algorithms applied pulse by pulse. This eliminates the need for storage of pulse height spectra, which are in many cases classified