Medium Energy Spin Physics

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Our group is active in research that uses spin-polarized beams andspin-polarized targets to study issues in fundamental and applied physics.Currently, our primary focus is in the search for new physics beyond theStandard Model by performing a precision measurement of parity violationin the scattering of polarized electrons by unpolarized electrons in aliquid hydrogen target. The experiment, which is now being performed atthe Stanford Linear Accelerator Center, should eventually provide the mostprecise measurement of the electroweak mixing angle at low energies.Recently, our group has joined the Star Collaboration at Brookhaven. Thislarge collider physics experiment is presently commissioning a program toscatter spin-polarized protons with high center-of-mass energies in orderto learn about the internal spin structure of the proton. The primaryquestion being addressed is 'how much do gluons contribute to the proton'sone-half spin'. Data over the next few years is expected to give thefirst direct glimpse into this important question. Finally, our group isalso involved locally at Caltech in the development of spin-polarizednoble gas, namely helium-3 and xenon-129, for use in nuclear physics andmagnetic resonance imaging.