Physicists have been investigating whether or notneutrinos have mass. Since the late 1960s, experiments have hinted that neutrinos may have mass. Theoretical models of theSun predict that neutrinos should be made in large numbers. Neutrino detectors on theEarth have repeatedly seen fewer than the expected number of neutrinos. Because neutrinos come in three varieties (electron, muon, and tau neutrinos), and because solar neutrino detectors have been primarily sensitive only to electron neutrinos, the preferred explanation over the years is that those "missing" neutrinos had changed, or oscillated, into a variety for which the detectors had little or no sensitivity. If aneutrino oscillates, according to the laws ofquantum mechanics, then it must have a mass.[7]
In 1984, McDonald's collaboratorHerb Chen at theUniversity of California at Irvine suggested the advantages of using heavy water as a detector for solar neutrinos.[10] Unlike previous detectors, using heavy water would make the detector sensitive to two reactions, one reaction sensitive to all neutrino flavours, the other sensitive to only the electron neutrino. Thus, such a detector could measure neutrino oscillations directly. Chen, Professor George Ewan, Professor David Sinclair, McDonald, and 12 other scientists formed the originalSudbury Neutrino Observatory (SNO) collaboration to exploit this idea in 1984.[6][11] SNO was to be a detector facility using 1000 tonnes of heavy water located 6,800 feet (2,100 m) underground in a mine outside Sudbury, Ontario. Chen died of leukemia in November 1987, however.
Professor McDonald is now participating in research with the SNO+ and DEAP-3600 experiments at SNOLAB, an expanded underground laboratory at the original SNO underground site and with the DarkSide-20k collaboration developing an experiment at the underground laboratory nearGran Sasso, Italy.
Arthur B. McDonald Canadian Astroparticle Physics Research Institute
The Arthur B. McDonald Canadian Astroparticle Physics Research Institute was inaugurally named the Canadian Particle Astrophysics Research Centre before renaming itself the Arthur B. McDonald Canadian Astroparticle Physics Research Institute in May 2018, in recognition of Dr. Arthur B. McDonald's trailblazing work making Canada a leader in astroparticle physics.
In the spring of 2020, amid theCOVID-19 pandemic and the ensuing shortages, McDonald became one of the leaders of a project to mass-produce mechanicalventilators at low cost.[13] McDonald has stated that the project was initiated by Princeton Professor Cristiano Galbiati who was locked down inMilan, Italy.[14] He inspired action by his colleagues on the DarkSide-20k Dark Matter physics experiment after recognizing the similarities between the requirements of a ventilator and those of particle physics experiments.[15] McDonald led the Canadian team with members from TRIUMF laboratory, CNL Chalk River, SNOLAB and the McDonald Canadian Astroparticle Physics Research Institute after strong positive response from the Directors of these institutions. The design, called the Mechanical Ventilator Milano, is based on the Manley ventilator but uses modern electronics wherever possible.[16] The details, first published on March 23 by about 150 collaborators, were released under theCERN Open Hardware Licence.[17] The project received the support of Prime MinisterJustin Trudeau who anticipated an initial order of 30,000 to Canadian hospitals from several suppliers.[18] An order has been placed for 10,000 units with Vexos, Markham.
