Neutrinos (meaning: "Small neutral ones") are elementary particles that often travel close to the speed of light, lack an electric charge, are able to pass through ordinary matter almost undisturbed and are thus extremely difficult to detect. Neutrinos have a minuscule, but nonzero mass. They are usually denoted by the Greek letter nu. Most neutrinos passing through the Earth emanate from the Sun, and more than 50 trillion solar electron neutrinos pass through the human body every second. Neutrinos are most often created or detected with a well defined flavor (electron, muon, tau). However, in a phenomenon known as neutrino flavor oscillation, neutrinos are able to oscillate between the three available flavors while they propagate through space.
In this RUI project, Professor Tagg and two undergraduate research assistants at Otterbein College will continue research on neutrino oscillations with the MINOS long-baseline neutrino oscillation experiment and begin research on the MINERÃA neutrino-nucleus cross-section experiment. MINOS is the flagship U.S. experiment on neutrino oscillations for the next several years. MINERvA is a valuable and opportunistic component of the future NuMI program that will coordinate with NOvA to make measurements of inclusive and exclusive neutrino-nucleus cross sections with the NOvA beam line with a fine-grained scintillation detector and the NOvA near detector. Objectives include nuclear structure measurements via a weak probe justified both on intrinsic interest and to help interpret current and future experiments.
Marvin Goldberg PO MPS/PHY/EPP
Neutrinos are fundamental sub-atomic particles, with the curious character that they travel through matter, hardly ever interacting. Our group at Otterbein University has been working on two important neutrino experiments based at Fermi National Laboratory: MINOS and MINERvA. The MINOS experiment shoots a beam of muon-neutrinos underground from Fermilab, near Chicago, to the Soudan mine in northern Minnesota (Figure 1). By measuring the energy and number of neutrinos as they start out and again at the end of the trip, we have precisely measured one of the unique properties of neutrinos: they change type as they travel. This can be seen in Figure 2: neutrinos of energy around 2 GeV of energy have ‘disappeared’ by the time the reach Soudan. The characteristics of this ‘dip’ allows an indirect handle on the neutrino mass. Other experiments have confirmed that the neutrinos have not actually disappeared, but have changed into a form that is not easily detectable by MINOS. The Otterbein group have participated in the MINOS experiment by doing detector energy calibrations, and maintaining the timing systems. Collaborators at Otterbein have also been heavily involved in an important side-project: measuring the speed the neutrinos take. (Contrary to some reports, neutrinos do in fact travel the speed of light, not faster.) The MINERvA experiment consists of a small, fine-grained detector in the same beam as MINOS. The purpose of the experiment is to measure and count the different ways muon neutrinos interact with matter. Specifically, we wish to measure the number and distributions of the resulting particles, and understand how this changes as the with the chemical composition of the detector "target". MINERvA has made good progress towards this goal. Otterbein’s unique contribution to this project has been to develop web-based software that let scientists and others "see" neutrino events in the detector, by showing which components observed charge particles resulting from the interaction. A picture of one such interaction is shown in Figure 3. Another version of the same software is used for educating high school students on particle decay and momentum conservation. Yet another version shows ‘live’ data coming from the detector, and is available to the public at http://minerva05.fnal.gov/Arachne/live. Work at Otterbein is done as part of the NSF Research at Undergraduate Institutions, and much of the work done is by undergraduate students, who were financially supported by this grant to help train them in scientific and technical techniques they will carry forward into their future careers.
