Brookhaven’s Relativistic Heavy Ion Collider (RHIC) began its cool-down on 1 November ready for the first injection of beam in December. Following a successful run earlier in the year, which included the first polarized proton running, RHIC is set to start the new run with deuterium on gold collisions. This provides a reference point for the gold-gold collisions that RHIC experiments were designed to study, since any departure from simple scaling between proton-gold and gold-gold collisions would point to new physics. Deuterium has been substituted for protons for practical reasons. The large-aperture dipole magnets that bring RHIC’s beams into collision would require realignment to handle proton-gold collisions, whereas deuterium-gold can be handled without intervention.
