The LHC Collimation system is a system designed to provide beam cleaning and limited passive protection to the LHC. The precise control of the jaw positions versus time and beam position has important relevance for machine protection of the LHC. The system is protected by various interlocks against wrong positioning. These interlocks are subject to thourough testing as part of MP proecdures.

The results of machine protection (MP) tests for the LHC collimation system are documented in EDMS reports and in the MTF database system (also used for production and quality control of collimators). Here we provide easy links to the relevant documents for all installed collimators, which are treated through the LHC collimation project.

Quick jump to:

General testing history:

Summary of Local tests

A document describing the specific machine protection tests can be found in:
https://edms.cern.ch/doc ument/889345/

And the link to the LHC-Machine-Protection can be found at Machine Protection Web Page

Global Tests:

The local mode was tested individually for each front-end in January 2010. The results are documented in the LHC elogbook. Access through this link.

The correct interlocking during a reboot of the Position Readout & Survey (PRS) unit was tested on March 4th, 2010. As the software is identical in all units, just one unit was tested from the CCC (prior tests were done by the hardware commissioning). Access through this link.

The correct interlock response to a power cut was tested parasitically during several perturbations of the electrical network. As some drivers (not on UPS) loose the power, the PRS unit (on UPS) was detecting that some jaw positions moved out of tolerance and interlocked the beam correctly. The response depends on vacuum forces, orientation and auto-retraction springs. Therefore only some collimator jaws run out of tolerance and never all collimators provide interlocks. In the documented case, the beam would have been stopped by interlocks from 13 collimators (more redundancy than necessary). The results are documented in the LHC elogbook.
Access through this link.

Interlocks from violating the valid gap for a given beam energy ("energy-dependent gap interlock") was checked during a global ramp test. The left figure shows the collimator gaps (staying constant, blue) and the energy-dependent gap interlock value (same for all collimators, red). The right figure shows the internal interlock state for the various collimators (0 = no interlock, not equal zero = interlock, different for different collimator types). Tested on Nov 11, 2009.

RBAC tests: done. Results to be added here.

Temperature interlock tests: Done manually end of 2008 for 80 then installed collimators. To be redone with automized procedure in March 2010. Results available under the following links: HTM XLSX

Test MCS-Collimator role: Only MCS-collimator can change MCS thresholds: EnergyThreshold, InterlockThreshold, InterlockThresholdFunct for the active beam process. Tested systematically during collimator remote commissioning (non-authorized persons frequently calling persons with MCS-collimator role to move collimators out of interlocked status). See for example this logbook page.

The MP reporting for the LHC collimation system is done in the MPP home tracking web page (linking back to the present page).

April 10, 2012
R. Assmann, S. Redaelli, A. Rossi, B. Salvachua, D. Wollmann