The first polarized Proton Collisions at the STAR experiment at RHIC

Abstract

The first run of transverse polarized protons at RHIC was recently completed which opened a new era exploring the spin structure of the proton. A first measurement of the single transverse spin asymmetry, $A_N$, for leading ${\pi }_0$ production from transverse colliding polarized protons at $\sqrt{(}s)=200$GeV, $X_F>0.25$ and $p_T\simeq 1-4$GeV was a focus of the STAR collaboration during the first polarized proton run at RHIC. Two new subcomponents have been added to the STAR experiment to carry out such a measurement in polarized proton collisions: a forward ${\pi }_0$ detector system at approximately $7.8$m of the STAR interaction region to reconstruct ${\pi }_0$ mesons from their decay products $({\pi }_0\to \gamma \gamma )$ and a beam-beam counter with large forward acceptance to provide a means of beam-related background suppression and relative luminosity measurement.

4 pages, 2 figures, Invited talk given at the Recontres de Moriond 2002 on QCD and High Energy Hadronic Interactions