Published: 2001
Total Pages:
Get eBook
Because the two photon cross section is proportional to Z[sup 4], heavy ion colliders offer an unmatched luminosity. However, because nuclei have finite sizes, the photon spectrum is gradually cut off by a nuclear form factor. For RHIC, this cutoff occurs at a few GeV; below this energy, RHIC will have the highest[gamma][gamma] luminosity in the world when it turns on. In addition to the high rates, because Z[alpha][approximately] 0.6, the nuclear environment provides a window to strong field QED and new phenomena like multiple pair production. To study[gamma][gamma] physics, regions where the nuclei interact hadronically must be avoided; this leads to roughly a factor of two loss in usable luminosity. The rates expected by the Solenoidal Tracker at RHIC (STAR) collaboration will be given. Backgrounds will be discussed, along with several rejection techniques.