Effect of quadrupole noise on the emittance growth of protons in HERA

The emittance growth in HERA at luminosity is about 1 πmm-mrad/hr. Intra-beam scattering and the beam-beam interaction coupled with tune modulation account for only part of the growth. Here we discuss the contribution of random tune fluctuations in the presence of nonlinear fields to the emittance growth of protons. At injection energy, a recent experiment with noise deliberately injected into a chain of correction quadrupoles showed no significant effect on the emittance growth and loss rates except at high noise voltages. The results of this experiment are compared with a tracking study. We also present the results of a study done of the emittance growth due to the beam-beam interaction in the presence of tune noise. A future experiment to determine the effects of tune noise on the proton emittance growth rate with colliding beams is planned