RUI: An Improved Measurement of the Electron-Antineutrino Correlation in Free Neutron Decay

Depauw University, Greencastle IN

Investigators

Abstract

The electroweak standard model describes two of the four fundamental forces present in the universe. By conducting experiments that probe with increasing sensitivity phenomena that can be described with this model, it is hoped discrepancies will appear that will lead to a more complete understanding of the weak interaction. This interaction is responsible for the decay, or transformation, of the neutron into a proton, electron and antineutrino. By studying the correlations between the properties of the neutron and its decay products, more precise tests of the electroweak standard model can be performed. One of these correlations, know as little "a", involves the direction of emission of the electron and antineutrino from the decay region. Other neutron decay correlations are known to within 1%, but little "a" is only known to 4%. The aCORN, "a" CORrelation in Neutron decay, collaboration is in the process of building an apparatus that hopes to provide a 1%, if not better, measurement of "a" using a method that bypasses some of the problems inherent in previous experiments. The apparatus will be tested at the Low Energy Neutron Source (LENS) at Indiana University and then moved to NIST (National Institute of Science and Technology) where there is a neutron source strong enough to perform the measurement. This grant supports the contributions of the aCORN collaborators from the DePauw University Nuclear Physics group, including undergraduate researchers. As such, in addition to increasing what is known about the weak interaction, these efforts will also provide an opportunity for undergraduate researchers to experience firsthand how research is conducted, and to acquire a set of general critical thinking skills that will serve them well the rest of their lives.