Experimental Nuclear Physics and Fundamental Interactions at Indiana University

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The strong interaction inside and between neutrons and protons, one of the four forces of nature, possesses some features that are poorly understood and other features that enable sensitive searches for new forces. The PI and his collaborators will measure different contributions to the angular momentum of the proton. The team will also search for nuclei which recoil from collisions with neutrinos and will use this data to search for new interactions and calibrate detectors to be used in the future to look for the neutrons from supernova explosions. In addition, the team will use neutrons to search for possible new forces of nature and measure the radioactive half life of free neutrons to test aspects of the Big Bang theory. The scientific impact of this work lies in the fields of nuclear physics, particle physics, astrophysics, and cosmology. In the course of conducting these experiments the PIs will provide excellent opportunities for a thorough scientific and technical education to many young researchers. The sensitive instrumentation and techniques developed for this research can be applied to neutron imaging of magnetic fields inside materials. The theory of the strong interaction, QCD, is still the most poorly-understood part of the Standard Model of particles and interactions. This project will support several PIs at Indiana University to collaboratively pursue selected scientific questions in strong interaction physics. The team will probe the poorly-known gluon helicity and quark orbital motion contributions to the angular momentum of the proton by analyzing data from polarized proton-proton collisions measured in the STAR detector at the Relativistic Heavy Ion Collider. The PI and his collaborators will also measure coherent neutrino-nucleus cross sections in various nuclei, including argon in a liquid argon scintillation detector, for neutrino energies that would be produced in a supernova explosion. This data will also constrain possible exotic interactions of neutrinos with nucleons. In addition, the team will search for parity-odd neutron spin rotation in liquid helium and for exotic spin dependent neutron interactions with matter at the NIST Center for Neutron Research. As such, this project will make possible better theoretical predictions of the primordial helium abundance from the Big Bang by measuring the decay rate of the neutron. The team will prepare apparatus for experiments to be mounted at Los Alamos and Oak Ridge National Laboratories to search for an electric dipole moment of the neutron with improved sensitivity to search for new sources of time reversal violation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.