Grant: Research Tools and Instruments

The nature of the missing matter in the Universe is one of the most important and mysterious unknown aspects in the physics field today (see the report by the P5 committee in the US, setting policy for the 2014- to 2023 period). Considerable effort toward the detection of missing matter has been expended by many research groups without success thus far. These searches are divided into direct and indirect dark matter searches, both of which play an important role in the search and the eventual discovery of this elusive component of the Universe. The proposed research explores a direct dark matter search through the construction of a novel 10kg Scintillating Bubble Chamber (SBC) detector at Queen's University, to be ultimately located at SNOLAB outside of Sudbury, Ontario.  The SBC collaboration builds on the world--leading research of the PICO collaboration {Phys. Rev. Lett. 118, 2051301 (2017)} and is an extension of the work with xenon bubble chambers {Phys. Rev. Lett. 118, 231301 (2017)}, expanding the sensitivity to lower mass dark matter, a region of particular interest in the community. As with the majority of dark matter projects, limitations are placed on the PICO results due to the inability to reliably separate background events from the nuclear recoils which are the signature of the dark matter interaction. The proposed detector improves dramatically on particularly the electron recoil discrimination using the scintillation of the target medium.  This has the potential to explore new dark matter possibilities inaccessible to other experiments, creating a world-leading complementary bubble chamber. This improvement necessitates a system to detect and process the light generated by events in the target area, which is the subject of this proposal.  Specifically, this proposal requests support for the specialized equipment required to translate the light-generated signals into a format compatible for processing, digitizing the information.  Also requested is support for the low-background cabling required to transmit those signals to the data collection system.  These cables must be specially constructed as the radioactivity of any more usual cables would swamp the detector and render it blind to any incoming dark matter.  Finally, the brains of the system (the data acquisition computers) allow for the collection and processing of the data. This system is being designed and commissioned at Queen's University by two PhD students who lead the relevant WBS areas (scintillation systems and electronics).  These students will be at the forefront of this exciting and groundbreaking measurement which has the potential to lead the field in an entirely new direction.