HIE ISOLDE cryogenics operation results and recent upgrades

Abstract The High Intensity and Energy ISOLDE (HIE-ISOLDE) enables the acceleration of medium to heavy radioactive isotopes at energies reaching 10 MeV per nucleon, a significant increase from the previous configuration limited to 2.8 MeV per nucleon. The journey towards this achievement involved a progressive deployment of radiofrequency cryomodules starting in 2015. In 2018, the final configuration was reached with successful operation of four high-beta radiofrequency cryomodules in series. This paper presents an overview of the operational results over the last 8 years, but especially focuses on the recent enhancements made in 2023 to the cryogenics system and tested during the last physics run. A comprehensive overhaul of the cryomodule operation process was implemented to minimize restart times following unexpected interruptions, to facilitate operators handling and to harden the process control structure. Hardware modifications have also been implemented to improve equipment availability and were successfully commissioned.