Nb3Sn accelerator magnets advance machine operation fields above 10 T and increase operation margins. Fermilab is working on the development of Nb3Sn accelerator magnet technology in collaboration with BNL and LBNL. These efforts are being coordinated in the framework of US-LHC Accelerator Research Program (LARP). A first step of this R&D includes the demonstration of the main magnet parameters (maximum field, quench performance, field quality, etc.) and their reproducibility using series of short models. Then technology scale up is performed using long coils. The status and main results of the Nb3Sn accelerator magnet development at Fermilab (both LARP and core program) will be presented and discussed.
The primary goal of this work is the development of large aperture high-performance Nb3Sn quadrupoles for the LHC luminosity upgrade. At present the upgrade is planned in two phases with the target luminosity for Phase I of ~2.5∙1034 cm-2s-1 and up to 1035 cm-2s-1 for Phase II. In Phase I the baseline 70-mm NbTi low-beta quadrupoles will be replaced with larger aperture NbTi magnets and in Phase II with higher performance Nb3Sn magnets. Recent progress in Nb3Sn accelerator magnet R&D suggests the possibility of using Nb3Sn quadrupoles in the Phase I upgrade, improving the LHC performance and providing an early demonstration of Nb3Sn magnet technology in a real accelerator environment. Possible hybrid optics layouts for Phase I upgrade with both NbTi and Nb3Sn quadrupoles, magnet parameters and issues related to using Nb3Sn quadrupoles as well as possible transition scenarios to Phase II will be also presented and briefly discussed.