Physics Students Engaged in National Research Project

Four fundamental forces - gravity, electricity, the strong force and the weak force- control all of the subatomic interactions that exist in our universe. The strong force dictates interactions between molecules in a nucleus while the weak force governs the process of radioactive decay.   The scientific community currently understands the first three forces well, but obtaining knowledge about the weak force has challenged physics researchers for decades. This gap in knowledge has created inconsistencies within the Standard Model, a theory that explains how all matter around us behaves and supports the concepts behind many advanced physics experiments. 

Andrew Morrison ’14 and Jacob Davidson ’15 are contributing to the aCORN Project, organized by the National Institute of Standards and Technology (NIST) to gain a better understanding of the weak force.  The project, which stands for “little-a Relation in Neutron Decay,” is a collaboration between Hamilton, Tulane University, DePauw University, Indiana University, University of Sussex, Harvard and NIST.

Morrison explained that a better understanding of the strong force led to a more comprehensive understanding of nuclear energy and resulted in the atomic revolution.  Researchers knew that subatomic interactions were occurring but they could not analyze the behaviors at the time.  Morrison believes that discovering properties about the weak force could lead to similarly substantial developments.  

With Professor of Physics Gordon Jones, the team’s specific task is to create a hot filament alignment system that will align a beam of electrons within a generated electric field for the final aCORN apparatus. The apparatus involves a tungsten filament that, when heated, releases electrons.  These electrons are fired through two copper sheets containing holes the size of a pencil tip in a three-meter long cylinder. The two copper sheets will receive the same electric charge and confirm that the apparatus is operating correctly if the electrons are fired and aligned correctly.

Morrison explained “when the neutrons undergo beta decay, they decay into a proton, electron and an anti-electron neutrino.”  The ultimate goal of the aCORN project is to measure the coefficient in angles of what direction these three components decay in, recognized as the unknown parameter “little-a,” in the Standard Model.

Electrons are such small subatomic particles that the experiment must be done in a vacuum.  If electrons were fired outside the vacuum, air molecules and other particulate matter would disrupt the free mean pathway of the electrons, or simply their desired path. 

Davidson mentioned that the “emptiest space we know of in the universe has a pressure of 10-12 torr.”  However, their vacuum can only achieve pressure of 10-5 torr and the seal must be broken each time they wish to obtain electrical readings.  The group is creating a stronger vacuum and developing a measuring device that can withstand the extreme conditions while working on the alignment system.

This research is helping  the aCORN project obtain more accurate results and thus develop a “better fundamental understanding at the atomic level in our universe,” according to Morrison.  The research’s most direct applications will help physicists better detect neutrinos, dark matter and dark energy.  

Both students contributed their growing interests in the sciences to past teachers in high school who made the material “come alive.”  Morrison would enjoy contributing to the green technology movement and pursue a career in developing more efficient and cleaner energy sources.  Davidson is also considering a career in a professional lab after graduating.  

Davidson is a graduate of Friends Central School (Pa.) and Morrison is a graduate of Upper Canada College (Canada).

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