Posted on 23/09/2011
Dr Jocelyn Monroe who has recently started a dark matter detection research group was recently awarded a European Research Council Starting Grant.
The nature of dark matter is one of the fundamental questions in physics today. Direct signals for dark matter interactions in terrestrial laboratories have remained elusive, although recent experimental results hint that a discovery of a weakly-interacting massive particle dark matter candidate (WIMP) may be within reach soon. The foremost challenge is distinguishing dark matter signals from backgrounds, the most uncertain of which come from neutrons. The research objective of this proposal is a world-leading dark matter search in a novel liquid argon (LAr) detector, with a new analysis approach to measuring neutron backgrounds. The DEAP/CLEAN program of LAr detectors is a new direction for dark matter searches, drawing on successful detector design from solar neutrino physics to building low-background experiments that scale simply to multi-tonne target masses, and on unique properties of LAr. Demonstration of this approach by the current 100 kg stage (MiniCLEAN) will break new ground for future experiments, and the next stage (DEAP3600) will be the world's first tonne-scale dark matter search. Both stages are under construction now, and will begin taking data in 2012 and 2013 respectively. At the 100 tonne scale, such a detector would be a new kind of observatory for fundamental physics at the low background frontier, testing predicted properties of dark matter, neutrinos, supernovae, and stellar evolution. Success depends critically on demonstrating the required background suppression.
This proposal addresses the key challenges of dark matter detection in two new ways, with the single-phase detector development to address scaling to very large masses, and by developing new methods to overcome neutron backgrounds. The tasks of this proposal are: (i) to develop an in-situ measurement of the neutron background from detector components, using a new technique of neutron tagging in LAr; (ii) to develop an active neutron veto detector for in-situ measurement of the cosmogenic neutron background, beginning with a measurement of the flux and energy spectrum in an existing prototype; and, (iii) to develop the dark matter search analysis, incorporating the measured backgrounds. The MiniCLEAN dark matter search sensitivity is a factor of 10, and the DEAP3600 sensitivity is a factor of 100, beyond current experimental results, with great potential for discovery.