Registration information Participation Rules The school is mainly addressed to the education of PhD and postdoctoral students without prior knowledge of neutron, X-ray and muon techniques. It is fully open to the national and non-national public. English is the school's language. The number of participants is limited to 120. Online registration Please register here online for the 10th PSI Summer School. The registration deadlines are: Deadline for registrations: June 30, 2011 - extended to July 10, 2011 The number of participants is limited to 120.