Studies in Experimental Nuclear Physics at Indiana University

Indiana University, Bloomington IN

Investigators

Abstract

This proposal will support continuing leadership roles for the Indiana University experimental nuclear physics group in three critical areas of basic research: (1) understanding the contributions from the internal "sea" of gluons and quark-antiquark pairs to the overall spin and magnetism of the proton and neutron; (2) elucidating the properties of nuclear matter at extreme temperatures, such as those believed to pertain during the earliest instants of the universe's evolution following its Big Bang origin; (3) testing the ability of the Standard Model of particle physics to account precisely for the properties and interactions of low-energy neutrons and of neutrinos. Measurements in category (1) will be made via two complementary techniques: studies of spin-polarized proton beam collisions at high energy exploiting the Relativistic Heavy Ion Collider (RHIC) facility and a major new addition to the STAR detector at that facility just completed by the Indiana group; comparative studies of neutrino-proton and neutrino-neutron scattering processes. Experiments relevant to category (2) will also utilize RHIC, with focus on the production in high-energy nucleus-nucleus collisions of mesons composed from a heavy quark-antiquark pair, and on differences between the interactions of quarks vs. gluons in the unique, hot matter produced in those collisions. Studies of fundamental particle interactions will include: completion of an ongoing experiment to confirm or refute a controversial signal for the oscillation of neutrinos from one type to another, a signal that cannot be easily accommodated in the emerging picture of neutrino states in nature; dramatic advances in the state-of-the-art for tests of nature's nearly perfect time-reversal symmetry, by exploiting innovative concepts to search for forbidden electric interactions of the spin of an electron; improved characterization of the normally masked weak interaction among neutrons and protons via highly sensitive exposure of deviations from perfect mirror symmetry in neutron-nucleus interactions and in nuclear structure. The proposed research will also involve the development of innovative new technology for tracking products from neutrino interactions and for producing beams of "ultra-cold" neutrons for fundamental interaction experiments