Results Achieved by the S1-Global Collaboration for ILC

The S1-Global cryomodule experiment [1] by ILCGDE (International Linear Collider, Global Design Effort) was planned to achieve “S1” goal, which is to operate at least one of cryomodule with 31.5MV/m ILC average gradient. The design, fabrication, assembly, experiment, and disassembly were done by the international collaboration based on ILC-GDE. The experiment hosted by KEK STF (Superconducting RF Test Facility at KEK) was performed from June 2010 to February 2011. The achieved gradient performance of the contributed cavities was average 30.0MV/m before installation, 27.7MV/m for single cavity operation after installation, and 26.0MV/m for 7 cavities simultaneous operation [2, 3]. The other goal of the S1-Global is to perform plugcompatibility concept by building one set of cryomodule from brought-in cavities and couplers of each laboratories. The half-size cryomodule-C was its demonstration built from INFN cryostat, two set of DESY cavities and couplers, and two set of FNAL cavities and couplers. The connection of cryomodule-C and KEK cryomodule-A was also another aspect of plugcompatibility. The S1-Global program was the truly international cryomodule experiment by the effort of GDE members and GDE participation laboratories. The program has demonstrated to realize the international cryomodule and their performance close to ILC specification. The issues of the current cryomodule technologies and what we need to solve in the next were identified.