Neutrino physicists at Virginia Tech are getting some well-deserved recognition from their scientific contemporaries – not with awards but with beam time from the Physics Advisory Committee at Jefferson Laboratory.

The Jefferson Laboratory continuous electron beam, created by a polarized electron source, is a widely sought after commodity in the expensive and purpose-built world of neutrino physics and costs about $1 million per week to operate. 

When Virginia Tech’s Camillo Mariani, assistant professor of physics and Omar Benhar, adjunct professor of physics and both members of the Center for Neutrino Physics, submitted a proposal to use the beam, they weren’t quite expecting the answer they received.

“Requests are graded on an A-D scale and usually successful requests are in the B to B+ range,” Mariani explained. “They are also usually sent back to have questions answered and for other reasons. When experiments are approved their beam time request is evaluated, and, more importantly, the experiment needs to be scientifically sound and in line with the National Lab mission. Until now, Jefferson Lab served the needs of the nuclear community only, and not the High Energy Physics community.”

However, because the interpretation of signals detected by current and future neutrino experiments aimed at measuring charge parity violation in the lepton sector such as the proposed billion dollar Long Baseline Neutrino Experiment, call for an accurate description of the neutrino-nucleus cross section, Jefferson Laboratory approved the proposal with a grade of A- and more importantly granted the study nine days of beam time.

“I believe part of the reason we were approved so quickly, and with such a high grade, is because of the importance neutrinos play in many areas of physics that we are really starting to appreciate,” Mariani said. “We received letters of support for beam from all the existing liquid Argon neutrino experiments in United States as well as from the Fermilab directorate.

"The real breakthrough for us,” Mariani said, “is that a national laboratory, that is historically dedicated to serve the needs of the nuclear physics community, endorsed the needs of the High Energy Physics community. To have done so in such spectacular fashion in a bad budget year is an excellent first step towards a broader collaboration between nuclear physics and neutrino physics.”

One key element of accelerator-based experiments such as the Long Baseline Neutrino Experiment is neutrino interactions, which is one of the main sources of systematic uncertainties. The Jefferson Laboratory experiment will be the first of its kind to study processes intended to give insight into neutrino-nucleus interactions on a complex nucleus like Argon.

As part of the preparations for the experiment, the team will work with Jefferson Laboratory to build an argon target – a device containing argon gas, cooled with a cryogenic system that will be bombarded with electrons produced by laboratory’s accelerator. The product of the electron interactions on Argon will be studied using the Hall-A spectrometers.

“The pairing of the nuclear and neutrino physicists for the experiment will be fundamental for future success of the Long Baseline Neutrino Experiment, as we try to discover charge and space parity violation in neutrino physics,” said Mariani.



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