Most software at CERN is open source. But you are right, for things which are quite specific to CERN, like the control systems of the accelerator, there's also

Most software at CERN is open source. But you are right, for things which are quite specific to CERN, like the control systems of the accelerator, there's also some proprietary code. Same for hardware actually, CERN develops open hardware too. https://opensource.web.cern.ch/ https://opensource.web.cern.ch/