The quadrupole short model magnet (MQXFS4), that went through endurance test in 2019, was retested at the end of 2021 to measure the magnetic effect of the beam screen. In this test run, following the 11th cooldown, the magnet reached ultimate current without quench at 1.9 K and at 4.5 K. The measured impact of b6 due to beam screen was found to be in agreement with the simulations, and the data will be presented on 9 February.

Moreover, in this run the magnet was powered for the first time above 18 kA, reaching 19.1 kA at 1.9 K, and 13.2 T peak field in the coils (1.8 T above field level corresponding to 7 TeV).  The magnet has been disassembled and the coils will be equipped with strain gauges to perform a series of tests to measure the performance degradation induced by high preloads, expected for spring 2022.

By Ezio Todesco, WP3 Leader