Evaluation of a (131o, 90o) Physics Optics for LEP

A new optics with phase advances of 131° and 90° in the arc cells hasbeen proposed for LEP. This note summarises the main results from theoptics evaluation procedure that is now routinely applied to new LEPoptics. This includes the study of the orbits, optics and dynamicapertures of an ensemble of imperfect machines with corrections similarto those applied in operation. It provides predictions of performanceand results of measurements that can be done when the optics iscommissioned.The results show that the dynamic aperture of this optics is muchsmaller than necessary for high-energy operation of LEP. A modificationof the sextupole configuration to reduce the detuning with amplitudedoes not help.