A First Baseline for the Magnets in the High Luminosity LHC Insertion Regions

The High Luminosity LHC (HL-LHC) project aims at accumulating 3000 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm fb}^{-1}$</tex></formula> in the years 2023–2035, i.e., ten times more w.r.t. the nominal LHC performance expected for 2010–2021. One key element to reach this challenging performance is a new insertion region to reduce the beam size in the interaction point by approximately a factor two. This requires larger aperture magnets in the region spanning from the interaction point to the matching section quadrupoles. This aperture has been fixed to 150 mm for the inner triplet quadrupoles in 2012. In this paper, we give a first baseline of the interaction region. We discuss the main motivations that lead us to choose the technology, the combination of fields/gradients and lengths, the apertures, the quantity of superconductor, and the operational margin. Key elements are also the constraints given by the energy deposition in terms of heat load and radiation damage; we present the main features related to shielding and heat removal.