Medium Energy Spin Physics

California Institute Of Technology, Pasadena CA

Investigators

Abstract

Our group is active in research that uses spin-polarized beams and spin-polarized targets to study issues in fundamental and applied physics. Currently, our primary focus is in the search for new physics beyond the Standard Model by performing a precision measurement of parity violation in the scattering of polarized electrons by unpolarized electrons in a liquid hydrogen target. The experiment, which is now being performed at the Stanford Linear Accelerator Center, should eventually provide the most precise measurement of the electroweak mixing angle at low energies. Recently, our group has joined the Star Collaboration at Brookhaven. This large collider physics experiment is presently commissioning a program to scatter spin-polarized protons with high center-of-mass energies in order to learn about the internal spin structure of the proton. The primary question being addressed is 'how much do gluons contribute to the proton's one-half spin'. Data over the next few years is expected to give the first direct glimpse into this important question. Finally, our group is also involved locally at Caltech in the development of spin-polarized noble gas, namely helium-3 and xenon-129, for use in nuclear physics and magnetic resonance imaging.