[Iwan-Zotow]

Accelerator itself is mostly CERN responsibility, but detectors are usually international collaborations. US contributed a lot to the CMS detector at LHC (as well as Russia, another non-member state).

https://science.energy.gov/~/media/hep/pdf/files/pdfs/uslhcc...

http://cms.web.cern.ch/news/using-russian-navy-shells