Grant: Subatomic Physics Envelope - Project

Most of the matter in the universe is not the normal visible baryonic matter that we are familiar with.  Motivated by the exciting potential to experimentally observe this dominant component of our universe, the dark matter, we are constructing an experiment which builds on recent research to extend our sensitivity to where many theoretical models predict that it should be detected.The probability of dark matter particles interacting  in terrestrial detectors is exceedingly small, requiring new techniques with very large target masses. DEAP-3 contains 3500 kg of liquid argon, will be the largest and most sensitive dark matter detector in existence, and will be operated at SNOLAB, the leading facility for this science.  Dark matter particles can in general be detected when they collide with a nucleus in a target material.  In the case of argon, light signals generated from this recoiling nucleus will have a different timing distribution for a dark matter particle than for most background events.  We will exploit this to very sensitively discriminate between dark matter particle-induced nuclear recoils and backgrounds from radioactive decays.   The expected background reduction available, based on research performed in a prototype at Queen's, is approximately a billion to one, and will allow a very sensitive search.An acrylic vessel with an 85 cm radius will be constructed to contain the volume of ultrapure liquid argon, which will be viewed by 212 photomultiplier tubes, and contained in a 6m diameter shielding tank of frozen ultrapure water. This project will place Canada as a leader in the field of dark matter particle detection, will attract international collaboration and top quality researchers to Canada and to Queen's.  We will leverage the infrastructure already present at SNOLAB and take advantage of the unique ultra-low background environment that is required for this research.