Measurement of Nucleon Spin Structure at RHIC

This grant supports the participation of the Penn State University in the STAR experiment at Brookhaven, including a full time research associate, Akio Ogawa, at Brookhaven Lab. The principal interest of the Penn State group involves the study of proton spin structure with experiments using polarized proton beams at RHIC. The approved upgrades to the STAR detector for this physics include an EMC (Electro-Magnetic Calorimeter). As this system comes online, STAR will be capable of reconstructing the higher rate, higher transverse momentum interactions that are needed for polarized structure function measurements. The utilization of these new features for a meaningful measurement of proton spin structure presents a very large software challenge. Penn State is developing software that will be required to simulate, collect and analyzed these data from STAR. Some polarized proton running at RHIC is expected each year for the next several years and will likely be in increasingly important component of the STAR program. The central objective of these experiments will be the measurement of the contribution of gluon fields to the proton spin.