BEAM DELIVERY LAYOUT FOR THE NEXT LINEAR COLLIDER

Abstract

This paper presents the latest design and layout of the NLC Beam Delivery System (BDS) for the first and second interaction region (IR). This includes the beam switchyard, skew correction and emittance diagnostics section, the collimation system integrated with the final focus, the primary and post linac tune-up beam dumps, and the arcs of the second interaction region beamline. The layout and optics are optimized to deliver design luminosity in the entire energy range from 90 GeV to 1.3 TeV CM, with the first IR BDS also having the capability of being extended to multi-TeV. REQUIREMENTS AND CONSTRAINTS The physics need to maximize the luminosity and energy reach sets the requirements on the layout of the Beam Delivery Systems (BDS) for the 1 st and 2 nd Interaction Region (IR). Ideally, both IRs should have equal capabilities up to at least 1.3 TeV in the Center of Mass (CM), with the same luminosity to within ~ 30%. However, in order to provide one IR with the possibility of extending to multi-TeV, it must have a straight-ahead tunnel, and therefore the two IRs can never be identical. The 2 nd IR needs a big bend to separate the beamlines and to create the desired crossing angle of 30 mrad, for compatibility with gamma-gamma collisions. Since the big bend consumes some of the beamline, the BDS of the second IR has to be shorter than for the first IR. The luminosity loss due to synchrotron radiation in a Beam Delivery scales with energy as ∆L/L ~ γ 7/4 / Λ 5/2 where Λ is the BDS length. Although the required BDS length scales only slowly with energy, as Λ ~ γ