Beam Tails and Background Storms with colliding Beams at 94.5 GeV

Transverse beam tails have been measured with the 1998 (102,90)-optics under physics data taking conditions. No broadening of horizontal tails have been observed when beams were brought into collision. However, enlarged beam tails in both transverse direction have been seen during periods of increased SR-photon background rates in the experiments. These 'background storms' could be triggered or stopped by small changes of the horizontal coherent tune around Q$_x$= 0.263 and Q$_y$= 0.208. Observations of background behaviour during storms are reported.