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Searching for Sterile Neutrinos

Professors Christopher White, and Bryce Littlejohn, and the PROSPECT Experiment

They may be nearly massless, largely inert, and so diminutive that an incomprehensible number of them pass through our bodies undetected each day, but neutrinos—subatomic particles discovered experimentally in 1956—may help to answer fundamental questions about the nature of matter in the universe. Two Illinois Tech neutrino scientists along with a team of postdoctoral researchers and graduate students are going even deeper as members of a national collaboration in search of the neutrino’s hypothetical cousin, the sterile neutrino.

Physics Professor Chris White, vice provost for academic affairs and research, and Bryce Littlejohn, assistant professor of physics, are part of the Yale University-based Precision Oscillation and Spectrum (PROSPECT) Experiment, recently awarded $3 million by the Department of Energy. Other Illinois Tech team members include graduate and postdoctoral participants Karin Gilje, David Martinez, Pranava Surukuchi, and Xianyi Zhang. The PROSPECT team will use the funding to build a detector that catches flashes of light produced by interactions of neutrinos emitted from the core of the High Flux Isotope Reactor at Oak Ridge National Laboratory. By precisely measuring the speeds of detected  neutrinos at different locations in their detector, PROSPECT will be able to determine if the reactor’s neutrinos are transforming spontaneously into their undetectable sterile counterparts.

While most of the neutrinos today were created at the time the universe formed, others are generated through nuclear decay at nuclear power stations and particle accelerators, and in naturally occurring objects, like stars. Scientists believe that sterile neutrinos (“sterile” because they do not feel electric and nuclear forces like other neutrinos and subatomic particles) can be much heavier than regular neutrinos; some have even suggested they may constitute the bulk of the universe’s ubiquitous-yet-unexplained dark matter. If discovered, it would represent the first-ever observation of a new particle outside the Standard Model of Particle Physics.  

As their contribution to the sterile neutrino search, the Illinois Tech team members are constructing a clean room at the university’s Mies Campus where they will fabricate and assemble the reflecting walls of the PROSPECT detector. Some of the group will then travel to Yale University to help construct the detector.

“Because of the natural radioactivity present at Earth’s surface, detecting these elusive particles near an operating nuclear reactor is a very challenging task,” says Littlejohn. “However, the neutrino physics opportunities this measurement would open up make it well worth the effort. By applying new technologies and techniques in PROSPECT, we will make the first-ever precision neutrino measurements in this environment.” In addition, he pointed out, the technology could potentially improve the way nuclear reactors are monitored and safeguarded, because neutrinos could be used to remotely detect illicit removal of nuclear materials from a reactor.