Head-on beam-beam compensation in RHIC

Wolfram Fischer, Brookhaven National Laboratory
Wednesday, Feb 14, 3:10 PM - Nuclear Science Seminar
NSCL Lecture Hall 1200

Abstract:  In a particle collider the electromagnetic interaction of one beam with the other, the beam-beam effect, is typically one of the most performance limiting effects. Operational head-on beam-beam compensation was first attempted in the 1970s in the 4-beam collider DCI but failed due to the unanticipated coherent motion of the beams. In 2015 operational head-on beam-beam compensation has been implemented in the Relativistic Heavy Ion Collider (RHIC) in order to increase the luminosity delivered to the experiments. We discuss the principle of combining a lattice for resonance driving term compensation and an electron lens for tune spread compensation. We describe the electron lens technology and its operational use, and report on measurements of the lattice properties and the effect of the electron lenses on the hadron beam. We also provide an estimate of the luminosity gain.