Flexibility and performance offered by very large crossing angles with values of Beta* between 30cm and 60cm for the LHC Phase 1 Upgrade

The large aperture triplet quadrupoles proposed for the LHC Phase 1 Upgrade provide an exceptional opportunity to increase the beam separation crossing angles and significantly reduce (even eliminate) the detrimental effects of the long range beam-beam interaction. The inevitable reduction in luminosity due to the large crossing angles can be offset by increasing the total beam current. This report presents the largest crossing angles that can be obtained using the currently available hardware in IR1 and IR5 for a range of low-beta values and a normalised aperture limit of about n1 = 7.5 at 7 TeV. The results clearly show that operational exibility can only be guaranteed for large crossing angles by increasing the dipole corrector strength in the defocussing plane at Q4, using an additional 2-in-1 unit for example. A peak luminosity of 2E34 cm-2s-1 should be achievable in at least one conguration with an ultimate beam consisting of the nominal number of bunches with nominal emittances and 1.7E11 particles per bunch. All calculations were performed using MAD-X with the LHC Phase 1 Upgrade optics version 2.0 for values of beta* between 30cm and 60cm.