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Description
At the Large Hadron Collider (LHC) at CERN, nearly 3600 ionization chambers composing the Beam Loss Monitoring (BLM) system are distributed along the ring and at each collimator. They are responsible for protecting the machine against energy deposition originated from beam losses by requesting the beam extraction when the measured signals are above certain predetermined thresholds. The setup of these thresholds is complex and requires a combination of simulations and measurements.
In preparation for the High Luminosity-LHC (HL-LHC) era, the bunch intensity has been pushed from 1.4e11 to 1.8e11 protons during the LHC Run 3. With this higher intensity, more power is required in the radio-frequency (RF) cavities to capture the beam and reduce beam losses due to off-momentum particles, in particular at the start of the energy ramp.
The present limitation on maximum allowed beam losses on the off-momentum collimation region is around 60kW and comes from the theoretical quench limit of the matching quadrupole magnets in cell 6 (Q6) which is based on the initial LHC magnet quench models. Supported by simulations, a dedicated machine development test took place in 2025 to assess in two steps if 200kW and 500kW beam losses from off-momentum particles could be sustained in the off-momentum collimation section without quenching the Q6 or any other magnets. This paper describes the procedure of the test carried out and discusses the main findings in terms of the power loss reached and the recorded loss patterns.
| Paper status | Resubmitted proceeding files received and assigned to an editor. Accepted. |
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