Document Type


Publication Date

Summer 2021


Neutrons can be stable only when bound to the nucleus of an atom through the strong force. For every passing second, there is a probability that any isolated neutron will decay into a proton, an electron and an antineutrino. However, for the past 15 or so years, the only two neutron lifetime measurement methods have consistently shown lifetimes differing by over 8 seconds. One of the lifetime measurement methods is called the "beam method: and the other is called the "bottle method." While the measured lifetimes from the beam and bottle methods differ, as shown in the figure titled "Published Neutron Lifetime Reports," the Standard Model of Particle Physics predicts that neutrons should have the same average lifetime under these two conditions. The Standard Model is a unified theory that attempts to describe how the universe works on the most fundamental level. The properties of every particle are described through the Standard Model, along with the mechanisms (outside of gravity) for how these particles interact with one another. Therefore, either the differing lifetimes are a result of imprecise measurements, or the differing neutron lifetimes present flaws in the physicists' current understanding of the Universe's most fundamental properties. The UCNtau experiment, using the bottle method, published one of the most precise neutron lifetime values ever in 2018. This summer, we performed a preliminary analysis on blinded UCNtau data taken during the 2020 run cycle at Los Alamos National Laboratory and made significant progress in extracting a blinded lifetime.


This material is based upon work supported by the National Science Foundation under Grant No. PHY-171446. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. This work is also supported by the Science Research Fellows program at DePauw University.