Beam-beam interactions in DAPhiNE: Numerical simulation and experimental results

Abstract

The e(+)e(-) collider DAPhiNE is a Phi-factory aimed to reach a luminosity as high as 5 x 10(exp 32)cm(exp -2)s(exp -1) at the Phi-resonance energy of 1,020 MeV in the center of mass. Since the machine energy is relatively low, the damping time takes a large number of revolutions (approximately 100,000) and the noise is weak. This means that even high order beam-beam resonances can affect the luminosity performance. The right choice of the working point is very important under these conditions in order to avoid the beam core blow up and distribution tail growth due to beam-beam interactions. Intensive numerical study has been performed in order to find a suitable working point. The point (5.150; 5.214) has been proposed for the beam-beam collisions at the commissioning stage. It has been proven experimentally that the numerically predicted working point provides the maximum luminosity in the allowable range of machine tunes during the commissioning. Moreover, it has been found in experimental runs that small variations of the tunes of the order of 0.001 with respect to that working point lead to a substantial reduction of the beam lifetime. This also agrees well with numerical simulations. In this paper the main numerical simulation results of beam-beam interactions in DAPhiNE are described and compared with experimental observations and measurements.