Construction and cold test of the superferric octupole for the LHC Luminosity upgrade

INFN is developing at LASA lab (Milano, Italy) the prototypes of five corrector magnets, from skew quadrupole to dodecapole, which will equip the high-luminosity interaction regions of the High Luminosity-LHC (HL-LHC). These magnets are based on a superferric design, which allows a relatively simple, modular and easy to construct magnet. This activity takes place within the framework of a collaboration agreement between CERN and INFN. The first prototype, a sextupole, has been tested in 2016. We present here the results of the cold tests, including the training performed at 4.2 K and the qualification at 2.2 K. of the octupole, that have been assembled and tested in 2017. We report also on the overall experience gained during constructions and tests and the improvements toward the series production. Other important results concern inductance measurements and quench studies.