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Fabrice Retière

Research topics 

The primary aim of my research is investigating the nature of dark matter and neutrinos. Dark matter is a key element of the standard model of cosmology, its nature is not known. I am involved in a suite of experiments (DEAP-3600 currently running; DarkSide-20k being constructed and ARGO being designed) using liquid argon to search for interactions of a dark matter candidate called WIMP, Weakly Interacting Massive Particle. I am also involved in the nEXO experiment, being designed to search for the neutrino-less double beta decay in liquid xenon. Discovery of such decay would show that neutrinos are their own anti-particle, show that the lepton number is not a conserved quantum number and provide a mean of measuring the absolute neutrino mass. My contribution to this research is through 1) the development of technologies enabling future experiments, 2) the development of solutions for experiments the design or construction stage and 3) the operation and data analysis of running experiments. 

Currently, my focus is on developing light sensing solutions for the detection of the light produced by liquid argon and liquid xenon. I am also leading the Light only Liquid Xenon (LoLX) experiment whose goal is to probe the early (first nanosecond) production of light in liquid xenon. The light sensing solution that I am developing is based on single photon avalanche diode (SPAD) arrays that come in two flavors, the mature Silicon photo-multipliers (SiPM) technology and the emerging Photon to Digital Converter (PDC) technology. With PDC, each SPAD is associated to a sensing and time stamping electronics channel, while the signals from many SPADs are combined together in SiPMs, limiting performances. My aim is the development of a solution capable of detecting single photon at the sub-nanosecond time scale with an efficiency better than 50% from vacuum ultra-violet (120nm) to near infra-red (900nm). Such performances would enable ground-breaking physics experiment and find numerous commercial applications. I am exploring a concept for the analysis of smoke applied to the detection and monitoring of forest fire based on the detection of UV-C (200-300nm) light scattering.  

Within the context of dark matter detection in liquid argon, I am contributing to the DarkSide-20k experiment being constructed under the Gran-Sasso mountain in Italy. TRIUMF is responsible for providing the data acquisition system that collect the information from the detector and make it available for analysis. DarkSide-20k is scheduled to start data taking in 2023. Within the context of neutrino physics, I am responsible for the development of the scintillation light sensing solution for the nEXO experiment currently at the design stage. nEXO is expected to be constructed at SNOLAB, Ontario, between 2022 and 2027. 
 

Head, Science Technology Department 

As head of TRIUMF Science Technology Department within the Physical Science Division, my role is to coordinate the resources provided by my department for the design and construction of a variety of physics experiments, including support to the Ultra-Cold Neutron and ISAC programs at TRIUMF, the ATLAS and ALPHA programs at CERN, and the various experiments at SNOLAB. The Science technology department resources include experts in detector systems, electronics and data acquisition as well as a machine shop specializing in unusual materials such as scintillator or ceramics. The Science Technology department focuses on efficient project delivery, while maintaining a vibrant R&D program in silicon detector for tracking and photon detection. The department also support projects the ARIEL project and is developing a new spectrometer for TRIUMF's condensed matter program. 
 

Student and postdoctoral research opportunities 

My research is led by students and postdoctoral research fellows, and I encourage interested applicants to contact me if they have any questions. My group currently includes 1 undergraduate student, 3 graduate students and 3 postdocs/RAs. The following positions are available for interested graduate students: 

  • Undergraduate (Co-op, Capstone or Honors thesis): Design and fabrication of a single photon air analyzer capable of differentiating different type of smoke with the goal of identifying forest fire. 
  • Undergraduate (Co-op, Capstone or Honors thesis): Development of a single photon light source based on parametric down conversion (photon entanglement) 
  • Undergraduate (Computing student): Development of a software toolkit for waveform analysis 
  • MSc.: Design of 300t liquid Argon experiment based on direct detection of the liquid Argon scintillation light 
  • MSc.: Combined measurement of the reflectivity and efficiency of Silicon Photo-multiplier from 120 to 900nm, with the aim of characterizing the contributions of electrons and holes in producing avalanches in silicon. 
  • MSc.: Development of a supercontinuum laser covering the vacuum ultra-violet to near-infrared spectrum. 
  • MSc.: Development and implementation of the strategy for testing and selecting the 10,000 SiPMs to be used in the nEXO experiment. 
  • MSc. or Ph.D.: Characterization of light emission in liquid Xenon during the first nanosecond with the aim of identifying new background rejection strategies for use in dark matter search and neutrinoless double beta decay search 
  • MSc. or Ph.D.: Development of back-side illuminated Photon to Digital Converter for the detection of Vacuum Ultra-Violet scintillation light 
  • MSc. or Ph.D.: Development of the triggering and filtering system for the DarkSide-20k experiment, and contribution to the early dark matter search analysis.