Forward Spin Physics at STAR

This project involves measurements of collisions between polarized protons at the

Brookhaven Relativistic Heavy Ion Collider. The measurement of scattering cross sections, with the

dependence upon initial state spin orientation, yields insight into the spin configurations of the

quarks and gluons that make up the proton.

The immediate goal for this project will be measurement of the dependence of forward neutral pion

production on the transverse components of the initial state proton spins. Toward this goal,

calorimetry is to be installed in the very forward directions of the STAR detector. This set of

measurements is expected to produce the largest spin dependence in proton-proton collisions at

RHIC and is naturally our first objective as the new polarized facility comes on- line. Recent

theoretical progress has increased the importance of this kinematic region. Complete

measurements in STAR, with both longitudinally and transversely polarized proton beams and with

calorimetry and tracking covering a wide range of scattering angles, have the potential to

characterize the quark and gluon spin structure of the proton.