User Registration


Visiting CERN/CLEAR (short term - 2 days max)

  • Access to CERN site for visitors is governed by the instructions available here.

Registration under the CLEAR Experiment (for long-term visits - 1 year max) 

Please check with your CLEAR contact the best way to register you while at CERN. The possibilities are the following:

  • Participants to CLEAR experiment should be registered as MPA (COAS or VISC) whenever a collaboration agreement with the Institute exists (for COAS registration only).
  • If there is no existing agreement or if the MPA registration is not possible, collaborators should be registered through the EXTERNAL status under the PROJ categoryThe instructions below concern the external registration only. MPA (COAS or VISC) will receive instructions from the department concerned in due time.
  1. The official procedure is described at here (access to this link possible only with a valid CERN account). This mainly requires to fill this form and date and sign the document “External Use of CERN Research Facilities". 
    • A CERN guarantor is needed (typically a CERN staff member).
    • On the registration form it might be convenient to indicate a start data which is earlier than your arrival. In this way additional formalities (user account activation, access request, online trainings) can be performed before your arrival.
    • Once completed, you or your guarantor should send the forms to
    • Once the registration is completed by, on the date indicated as started date in the registraton form, a new CERN account will be created.
  2. The CERN account needs to be activated:
    • In person:
      • In this case you should first obtain your CERN access card - see below - by coming to building 55 (next to CERN entrance B) prividing an ID card or passport.
      • Afterwards you should first badge your new access card at reader available on the ground floor.
      • The CERN account account can then be activated in the office at the second floor.
    • Before your arrival to CERN:
      • send an email to the CERN ServiceDesk asking for the “Account activation for External” activate your account and obtain the related credentials.
      • A copy of an ID or passport will be requested.
      • You will receive all necessary instructions, but basically you will have to log in to the account configuration wizard at
      • Note that you will need to follow the Computer Security online training (see below) within 5 days of your activation, otherwise the account will be blocked. 
      • For further details, see also this page and this page.
  3. Request access to CLEAR premises:
    • with a valid CERN account, one can ask for access to the facility via ADAMS interface. Typical access to be requested are:
      • "CTF3 control room" -> main control room of CLEAR (requires special safety courses - see below)
      • "CTF3 & CTF2" -> actual accelerator (requires special safety courses and dosimeter - see below)
      • "CTF Klystron gallery" -> technical infrustructure, normally not access needed for users (requires special safety courses and dosimeter - see below)
    • ​For "externals" it is the responsibility of the CERN guarantor to do the request and/or verify if all required conditions are met. Apparently, "externals" are not allowed to make access requests in ADAMS.
  4. Online training courses has to be followed on the CERN Learning Hub:
  5. ​Obtain a CERN access card:
    • At your first arrival to CERN, you will obtain a CERN access card at building 55 (next to CERN entrance B) - ground floor - providing an ID card or passport.
      • If you didn't do it before, you can profit of this time to also activate your CERN account - see above.
    • If you will arrive outside working hours, you might still access CERN site if you made a booking at the hostel.
  6. A personal dosimiter is necessary to access certain areas of CLEAR (e.g. the accelerator itself, but not the control room). One can obtain a temporary dosimiter from the Dosimetry Service in building 55 (after having passed the necessary online courses).
    • Note: such dosimeter is only valid for 2 months (cumulative). After your visit be sure to bring back your dosimiter to building 55

Booking a room in the CERN hostel:

  • According to the hostel rules, externals are allowed to stay at the CERN hostel up to 90 days.
  • If you have a valid CERN account, your booking at the CERN hostel can be managed from here:
  • If you do not have a CERN account yet, you can write an email to indicating your name, your status (e.g. EXT PROJ), your booking dates, the name of a CERN guarantor.
  • Unless the room is paid by a CERN Budget Code, you will be requested to confirm your bank coordinates directly by calling the CERN hostel.