Design Studies for the Low-Beta Quadrupoles for the LHC Luminosity Upgrade

In this paper, we outline the present status of the design studies for the high-luminosity Large Hadron Collider, focusing on the choice of the aperture of the inner triplet quadrupoles. After reviewing some critical aspects of the design such as energy deposition, shielding, heat load, and protection, we present the main tentative parameters for building a 150-mm-aperture Nb
₃
Sn quadrupole, based on the experience gathered by the LARP program in the past several years.