A calculation of the dynamic aperture of the LHC at collision

The dynamic aperture for version 5.1, with a 300 /spl mu/r crossing angle at IP1 and IP5, of the Large Hadron Collider (LHC) lattice has been estimated using the tracking code TEVLAT. The dynamic aperture calculated here is due to the magnetic field errors in the high gradient quadrupoles (MQX) in the two low-/spl beta/ interaction regions at IR1 and IR5. No errors were assigned to the magnets in the arc regions of the lattice, nor were beam-beam effects incorporated. The dynamic aperture is expressed in terms of the /spl sigma/ of the beam corresponding to the beam emittance of 3.75 mm mr. With only short term tracking, the combined effect of the multipoles and the crossing angle is to yield an average (over multipole coefficients generated with 100 different seeds) dynamic aperture of /spl ap/11.7/spl plusmn/1.2.