Four Tufts University Physicists Play Key Role In Dept. Of Energy's Neutrino Research

Medford/Somerville, Mass. -- Four physics researchers at Tufts University, working with the Department of Energy's Fermilab and several other universities, have proven the existence of the tau neutrino, the last piece in a puzzle physicists call the Standard Model of elementary particles. The findings represent the culmination of almost six years of experiments and data analysis, and bring to a close a 25-year quest to validate a long-accepted hypothesis about the existence of the tau neutrino.

   The team of researchers from Tufts' High Energy Physics Group was headed by Professor Jacob Schneps, a long-time faculty member and one of the group's founders. To Schneps, the tau neutrino observation was inevitable but was nonetheless vital.

   "This experiment was really hard, because the tau lepton produced by the tau neutrino lives only a tenth of a trillionth of a second," Schneps said. "It travels a fraction of a millimeter before it disintegrates. And the events themselves se are so incredibly rare. Even after three years, we only found four of them--but they were very convincing."

   Schneps and his Tufts colleagues, all experts in neutrino physics, were charged with designing and assembling the muon identifier used in the experiment, which was conducted at the government laboratory in Illinois. The enormous apparatus, approximately as large as a two-car garage door, helped establish the presence of tau neutrinos by removing background events that can mimic a tau event. Other detectors, contributed by U.S. and foreign universities, were likewise crucial to the experiment.

   Six other neutrino research projects at Tufts are already under way, including two designed to find the mass of neutrinos. In one of these projects, Tufts physicists and other university collaborators are working with Fermilab to measure the mass of neutrinos by firing a particle beam underground from Illinois to northern Minnesota. Neutrinos are omnipresent in the universe, and evidence of a measurable mass would have profound implications on the fields of high-energy physics and astronomy.