HiLumi activities


Delivered & validated for WP5

Deliverable D5.1: Simulation models for beam loss approved
Deliverable D5.2: Simulation models for energy deposition approved
Deliverable D5.3: Beam halo simulations approved
Deliverable D5.4: Energy deposition simulations for upgraded collimation layouts approved
Deliverable D5.5: Conceptual design of IR collimation approved
Deliverable D5.6: Technical design of IR collimation approved


Several HiLumi milestones are within the scope of the ColUSM. The relevant results are summed in this page. A more complete description of tasks, deliverable and milestones can be found in this document.

MS48: Set up of models and implementation of upgrade optics

MS49: Assessment of beam halo losses in various upgrade scenarios

The different upgrade optics, developed by MadX, have been implemented in SixTrack for the set up of cleaning simulations.

Plots illustrating the ATS optics can be found on the halo simulation page:
reference ATS case
The results of the SixTrack simulations with the same optics is also on that page.

One of the main modification of the collimation system for ATS is the addition of two Dispersion Suppressor Collimators (TCLD), to protect from the loss clusters in the Dispression Suppressor of IR7. To make room for one these collimators, an 8.3T dipole is replaced by two shorter 11T dipoles. The implemetation is described on this page.

The setup and results of the halo cleaning simulations are available here:
11T dipoles and DS collimator, Beam 1.

Another main modification considered is the addition of the same system in cell 10 around IP2, in order to intercept the secondary ion beams. Details of installation are on the page:
Models of Dispersion Suppressor Collimator
It includes:

  • a description of the model used for the Dispersion Suppressor Collimator and the 11T dipole
  • the MadX scripts used to implement the model in the ATS optics

MS50: Assessment of energy deposition

This milestone concerns the assessment of tools for energy deposition studies for IR collimator solutions. The simulation results rely on integrated tools for the particle tracking and for the energy deposition studies that have been set up throughout the years (cf. previous Milestone, Models of Dispersion Suppressor Collimator). Recent work within the WP5 team was aimed at assessing the results of the tools used for the specific purpose of the HL-LHC collimation studies. The assessment is based on comparisons between different tools and - when applicable - on the comparison to experimental data collected during the LHC Run 1.

The assessment of energy deposition studies is achieved in different ways for the simulation cases relevant for the WP5 studies:

  • Cleaning limitations from collimation losses are benchmarked against quench tests carried out at the LHC during Run 1 at 3.5 TeV and 4.0 TeV.
    In particular, recent tests done in 2012 are used to assess the loss prediction (halo tracking and energy deposition) in the dispersion suppressor (DS) regions in IR7. This is the most relevant case for cleaning limitations to the total proton intensity at the LHC.

    The simulations of energy deposition have been compared with he measurements of the collimation quench test performed in February 2013 E. Skordis, Collimation Review 2013.
    This is summarized here:
    Quench test: energy deposition simulations & loss measurements

  • Comparison with measured losses during ion operation in the vicinity of the LHC experiments.
    In particular, loss locations that will be addressed by local collimation in the DS are assessed. This is relevant case for possible ion limitations after the IR2 luminosity upgrade foreseen for ALICE.

    Studies of energy deposition for ions have been performed by the FLUKA team for two possible collimator designs G. Steele, ColUSM#30.
    The expected loss location of the secondary beams agree with the measurements in the LHC (J. Jowett).
    More details on the ions studies are available here:
    Ions simulations and measurements

  • Benchmark of simulation results against measurements of p-p debris losses in the high luminosity experiments.
    Data were collected in 2011 and 2012 in different conditions, including cases when dedicated scans of physics debris collimators were performed and when the TOTEM Roman pots were inserted close to the circulating beams. In addition to the comparison to measurements, benchmarks of FLUKA results against SixTrack loss maps for far losses are on-going.

    Studies of energy deposition in IR5 have been performed by the FLUKA team to evaluate the TCL6 and to compare with BLM measurement L. S. Esposito, CWG, 2014.

    FLUKA simulations of debris in the straight section were presented at the 2nd annual meeting: Energy deposition studies for TCLs in IR1/5 (L. S. Esposito et al.).

MS51: Definition of new IR collimation solution

R. Bruce, A. Lechner, S. Redaelli - Milestone Report 2014

MS52: Verification of new IR collimation solution in simulations. Possible iteration in design

One aspect of a new IR collimation solution is the study of collision debris around IP1 and IP5. These debris could be intercepted by extra TCL in cells 4, 6 and 7, in addition to the one already installed in cell 5.

The setup and results of debris cleaning simulations for different cases are available here:

MS53: Final report

The final report will be posted here when available.