Featured Items

White Paper on Sterile Neutrinos Released

      After 6 months of effort involving scientists from 19 countries the sterile neutrino white paper is now available in the preprint archive (arXiv:1204.5379 [hep-ph]). Building upon the recent Sterile Neutrinos at the Crossroad Workshop, held at Virginia Tech (September 26-28, 2011), the white paper presents the theoretical context, details the astrophysical and cosmological evidence, examines the experimental and evidence both for and against the sterile neutrino, and explores the different ideas and proposals for new experiments to test the hypothesis of a light sterile neutrino. As a white paper, its target audiance is policy makers, but the early reviews indicate that it will also be an excellent reference document for scientists working in the field.

Daya Bay Measures the Neutrino Mixing Parameter sin²2θ₁₃

      In a letter submitted to the Physical Review (arXiv:1203.1669[hep-ex]), the Daya Bay Collaboration, including mebers of Virginia Tech's Center for Neutrino Physics, announces the first observation and measurement on the neutrino mixing parameter sin²2θ₁₃. The mixing angle θ₁₃ governs the rate of electron neutrino conversion to muon and tau neutrinos at baselines consistent with atmospheric oscillations. The hunt for theta;₁₃ is currently the focus of several major experiments world wide, who are using either electron antineutrinos from nuclear reactors or beams of muon neutrios/anitneutrinos produced at accelerators.

      In reactor neutrino experiments such as Daya Bay, the oscillation is observed as an electron antineutrino disappearance at a distance of about 2 km from the reactor. The effect can only be measured with confidence in the comparison of detectors placed near the reactor cores – which measure the neutrino flux before significant oscillation has occured – to detectors placed farther away – at a location close to the oscillation maximum. In this way uncertainties associated with antineutrino production in the reactor, the interaction cross section in the detector, and to a lessor degree detector efficiency will cancel in the near/far detector comparison. Daya Bay Collaboration is the first to apply this technique and report results, finding:

sin²2θ₁₃=0.092±0.016(stat.)±0.005(syst.).

The measured vs. expected signal in each detector, assuming no oscillation. Reactor and survey data are used to compute the weighted average baselines. The oscillation survival probability at the best fit value is given by the smooth curve.

Read the full press release.

Borexino Sees First Evidence of Neutrinos from the Rare pep Solar Fusion Process

      In a recently published article (Phys.Rev.Lett. 108, 051302) the Borexino Collaboration, including members of the Virginia Tech group lead by Prof. Bruce Vogelaar, announced a first ever observation of neutrinos from the sun consistent with the rare fusion process in which two light hydrogen nuclei, or protons, combine with an electron to make a heavy hydrogen nucleus, known as a duteron, and an electron neutrino. This process know as pep fusion is about 500 times less likely than the primary pp process in which a two protons combine to to make a duteron, and electron and an electron neutrino. While neutrinos from the pp fusion process are much more common, neutrinos from the pep process have higher energies, which makes it possible for them to be seen in the Borexino detector.

      The Borexino observation is consistant with the Standard Solar Model prediction for flux of neutrinos from the pep fusion combined with the best fit model of neutrino oscillations.

See the Article in APS Spotlight

Minerva Experiment Demonstrates Neutrino Communication

      The Minerva Experiment at Fermilab successfully transmitted a message coded in neutrinos. In a paper submitted to the archive (arXiv:1203.2847[hep-ex]), the collaboration describes their test, in which the word "neutrino" was encoded in the pattern of neutrino pulses sent from Fermilab's NUMI beam line and reconstructed from the pattern of neutrino interaction observed in the Minerva detector, located 1 km away. They found a data transmission rate of 0.1 bits/second and an error rate of 1%.

      The Minierva message is the first successful attempt at neutrino communications, demonstrating the possibility of neutrino communications as proposed by Center for Neutrino Physics member Patrick Huber. In a 2010 paper published in Physics Letters B (Phys.Lett.B692, 268), Prof. Huber outlined a method for communicating with submerged submarines using high energy neutrino beams. The Minerva result brings the realization of this technology one step closer.

Feature Article Archive

News & Events

Leo Piilonen, of the Center for Neutrino Physics, has been elected as one of the spokespersons of the Belle Collaboration. As spokesperson, Prof. Piilonen will help guide the collaboration as it upgrades to the Belle II experiment.

CNP Director, Leo Piilonen, is selected as next Chair of the Physics Department. Prof. Jonathan Link is selected to replace, Piilonen as Director of CNP.

We mourn the death of Prof. Ramaswami "Raju" Raghavan who died suddenly, early Thursday morning (Oct. 20, 2011). Prof. Raghavan was an outstanding scientist, and a tremendous human being. The example of his life will continue to guide us.
      To read more about Prof. Raghavan please visit http://www.phys.vt.edu/~raghavan/.