Transverse Beam Tails and Aperture in the 1998 102/90 Physics optics

In the 90/60 optics horiyontal tail measurements were compatible with gaussian beams up to a maximum stable emittance [1-3]. In other cases, including the 102/90 lattice tested at the end of 1997, a significant broadening of the tails was observed for large emittances. The 102/90 optics of this year uses a different sextupole scheme with reduced anharmonicity [4]. The tail measurements performed in the horizontal plane as a function of damping particition are now compatible with nearly gaussian beams up to rather large emittances. The beam was stable (lifetime over 1 hour) for emittances up to about 150 nm which suggests that the dynamic aperture was at least 5.5.\sqrt 150 nm = 2.1. \sqrt um. Some dependence on the tails for high emittance as function of a trim in anharmonicity was observed.