Grant: Subatomic Physics Envelope - Project

In the last three decades, tremendous advances in experimental particle physics have enabled significant progress in the search for neutrinoless double beta decay (0?ßß) and the direct detection of dark matter (DM). Tabletop instruments have become multi-ton underground detectors with excellent sensitivity to extremely rare interactions. Critical to this progress has been the reduction of residual natural radioactive backgrounds in the detectors by many orders of magnitude, accomplished mainly through material screening, before and during detector construction. Every material and each component for building such giants has to be thoroughly analyzed and, if possible, optimized, as the slightest natural radioactive contamination can ruin the experiment's sensitivity by overwhelming the expected signal. Many technical advances, as well as underground installation have contributed to the success of past and current experiments. But we have reached material screening requirements that often cannot be met by conventional methods. Accelerator Mass Spectrometry (AMS), an established technique in other fields, has already shown promising increases in sensitivity by using a a particle accelerator. It also offers the following unique and outstanding advantages: - direct scanning of electrically conducting materials; this compares favourably with the only other direct method, gamma spectroscopy using a Ge detector, - total molecular background suppression, an advantage over regular high sensitivity mass spectrometry techniques like ICP-MS. - single ion sensitivity using gas ionization detectors and high resolution alternating magnetic and electric sectors, that enable noise-free detection and a series of signal to background optimization strategies. - application to screening for medium/short lifetime isotopes, e.g. Pb-210 in a wide array of plastics and other insulators used for in-situ electronics and high voltage systems, In this request, we improve AMS material screening techniques, targeted to three specific projects that have significant Canadian contributions and leadership: nEXO, NEWS-G and DEAP/DarkSide, and which are considering operating at SNOLab, one of the deepest and cleanest underground laboratories in the world. We propose to investigate the trace radioactivity, from the Rn-222 incorporated during manufacturing, by measuring the concentration of Pb-210 (a Rn-222 daughter product) in copper, titanium, acrylic and thin polymer films. The A. E. Lalonde AMS (Lalonde AMS) facility at the University of Ottawa, the only AMS laboratory in Canada, operates a 3 MV, multi-element AMS system, specifically designed to sensitively and efficiently measure elements as massive as the actinides. AEL-AMS has implemented sample preparation chemistry labs equipped to handle a wide array of heavy isotopes and sample matrices and has a mandate to develop new applications and the required protocols and technical infrastructure to facilitate such analyses