On behalf of the CERN Collimation Team and FLUKA team… 2nd EuCARD-2 ColMat-HDED Annual Meeting GSI Darmstadt (Germany), December 4-5, 2014 Updated failure scenarios and damage limit of TCTs and status of SixTrack simulations Elena Quaranta On behalf of the CERN Collimation Team and FLUKA team…

Motivation of the study Eucard2 WP11 – Task 11.4 Outline Motivation of the study Eucard2 WP11 – Task 11.4 Updated failure scenarios and damage limit of TCTs Status of SixTrack simulations with advanced collimators Summary and Outlook WP11 annual meeting – GSI, Dec 4th 2014

Motivation of the study

The LHC upgrade challenge Increase luminosity Increase stored beam energy up to 700 MJ HL-LHC LHC (design) ≈ factor 5 than present value! LHC (run 1) Increase beam energy up to 7 TeV NEVER reached so far in accelerator rings! WP11 annual meeting – GSI, Dec 4th 2014

Why collimation upgrade? The collimation system plays a crucial role to achieve the future LHC challenges: Cleaning performance determines the maximum beam intensity Collimator materials defines the machine impedance at high energy Collimation hierarchy determines β* reach The upgrade of the collimation system is integral part of the design study for HL-LHC. β* reach is the minimum β reached at the IP WP11 annual meeting – GSI, Dec 4th 2014

Each collimator plays its role Collimators installed in IR7 (betatron cleaning) and IR3 (momentum cleaning) Tertiary collimators (TCTs) installed around the experiments to protect magnets and detectors Beam dump protection devices in IR6 – should intercept beam in case of fast dump failures More than 100 collimators organized in a multi-stage system WP11 annual meeting – GSI, Dec 4th 2014

The multi-stage collimation system Collimators are designed for: Cleaning: protect cold aperture from unavoidable beam losses as particles drift out from the core of the beam (SLOW losses). Protection: protection of accelerator components in case of abnormal beam losses. Critical: VERY FAST losses not protected by BLMs (Asynchronous Dump). The system performance relies on the well-defined hierarchy between collimator families and machine aperture. WP11 annual meeting – GSI, Dec 4th 2014

Collimator materials and upgrade TCP and TCSG made of Carbon-Fiber-Carbon composite (CFC) Very robust to beam impact High impedance (not metallic material) (main contribution from TCSGs) TCT and Absorbers made of tungsten heavy alloy (Inermet180) High particle absorption Low robustness to beam impact Looking towards the collimator upgrade New materials and new designs for secondary collimator jaws to decrease impedance contribution Guarantee same or higher level of beam cleaning Compatibility with failure scenarios and improved robustness at critical locations (TCT by factor 100-1000 higher) WP11 annual meeting – GSI, Dec 4th 2014

Studies and programs ongoing CERN LHC Collimation project: Overall responsibility of LHC collimation, including operation, performance monitoring and optimization, remote handling, improvements of present system, … FP7 HiLumi WP5: Design of collimation in the interaction regions, upgrade for cleaning. FP7 EuCARD2 W11: New materials and new collimator design concepts. Strong and long-standing external collaborations: US-LARP, Kurchatov, Fermilab (energy deposition),... WP11 annual meeting – GSI, Dec 4th 2014

WP11 objectives WP11: Collimator MATerials – High Density Energy Deposition Task 11.1: Coordination and Communication Task 11.2: Material testing for fast energy density deposition and high irradiation doses Task 11.3: Material mechanical modelling Task 11.4: Material specification Simulation results used to iterate on material specifications Use simulation codes to evaluate potential advantages and disadvantages of materials studied in 11.2 and 11.3 WP11 annual meeting – GSI, Dec 4th 2014

Updated failure scenarios and damage thresholds of TCT

How to calculate damage limits for fast dump failures? So far: Shock waves formation and propagation (Autodyn) 1 single bunch impact TCT as “isolated” system parallel impacting beam Energy deposition in TCT (FLUKA) Now… Present damage estimates for Beam Dump Failure: 5e9 protons (Plastic damage) 2e10 protons (Fragment ejection) 1e11 protons (“5th axis” – catastrophic case) To more details, see A. Bertarelli-MPP workshop 2013 Shock waves formation and propagation (Autodyn) Energy deposition in TCT (FLUKA) Particle tracking (SixTrack) In the past: limit based on FLUKA simulations… All LHC ring Many bunches All collimation system 1 dump kicker pre-firing Realistic particle tracking Which the advantages in adding one more step in the simulation chain? To get VERY REALISTIC PARTICLE DISTRIBUTION AT TCT! WP11 annual meeting – GSI, Dec 4th 2014

SixTrack simulation setup Single dump kicker magnet pre-firing (Time profiles provided by B. Goddard) Energy: 7 TeV Gaussian beam (beam emittance=3.5 μm) Separate simulations for each bunch in the train (25ns spacing), different kicks. Perfect machine (only “error” due to IR1/5 TCTs setting: put further in as they should be to simulate beam losses in these collimators after dump failure) Collimator settings: 2 σ retraction between primary and secondary collimators Different optics used: Nominal 7 TeV (β*=55cm): B1 and B2 HL-LHC (β*=15cm): B2 ATS 2015 (β*=55cm): B2 WP11 annual meeting – GSI, Dec 4th 2014

Simulated failure scenarios Scan over TCT settings for different machine optics Compare with previous damage estimates Select few relevant cases for further studies with higher statistics, trying to have cases with significantly different number of impacts TCT setting < “dump protection” TCT setting >≈ “dump protection” TCT sees also primary beam. TCT sees only particles scattered out by dump protection collimators. WP11 annual meeting – GSI, Dec 4th 2014

Summary of simulation results Average impact coordinate of each simulated bunch on the TCT in different scenarios. Similar to what we expect for the LHC restart in 2015 Please pay attention to the different scale!! WP11 annual meeting – GSI, Dec 4th 2014

From SixTrack to FLUKA Nominal 7 TeV optics B2 (IR1/5 TCT @ 10.5σ) Impact distribution (SixTrack) Courtesy E. Skordis Distance from center of collimator [cm] Energy density [GeV/p/cm3] Energy deposition map (FLUKA) Courtesy E. Skordis WP11 annual meeting – GSI, Dec 4th 2014

Energy deposition in TCT Status of the study DONE! Particle tracking (SixTrack) Provide impact particle coordinates for different scenarios (input for FLUKA) ON GOING! Provide energy density maps (input for AUTODYN) Energy deposition in TCT (FLUKA) ON GOING! Hydrodynamic simulations to estimate new thresholds of damage for tertiary collimators Shock waves formation and propagation (Autodyn) WP11 annual meeting – GSI, Dec 4th 2014

Sixtrack simulations with advanced collimators

Introduction MoGr CuCD Novel advanced composites under development for the next generation of collimators to address impedance issue shown by CFC secondary collimators during 2010-2013 run. MoGr CuCD Copper-Diamond composite Molybdenum-Graphite-based composite Effect of advanced collimators on the LHC beam cleaning has to be studied: SixTrack material database up to date to model new composites. Particle tracking simulations of collimation efficiency with advanced collimators Energy deposition studies in the IR7 with new loss profiles  feedback to the new collimator design Importanza di questi studi: Come cleaning non cambierà molto (e lo sappiamo già) ma ci servono come feedback per aggiornare collimator design e come input per dpa calculation WP11 annual meeting – GSI, Dec 4th 2014

Updated SixTrack material database 2 materials added: MoGr, CuCD “Atomic” properties and reference cross sections at 450 GeV calculated averaging the property (pi) of the i-th component on its weight percentage (wti%) in the composite: Material Properties MoGR CuCD Composition (wt%) 20%v (init) Mo 80%v C (graph. + carbon fibers) 62% Cu 37.5% diamonds 0.5% B ρ [g/cm3] 2.65 5.4 Z 7.384 11.78 A [g/mol] 14.809 24.142 X0 [cm] 13.878 4.801 Nuclear radius [fm] 2.947 3.468 Mean Ex. Energy [eV] 92.22 147.15 σpNtot [barn] 0.4762 0.6572 σpNinel [barn] 0.3088 0.4158 σruth [10-2barn] 0.012 0.027 pi from Particle Data Group database Note: values in the table to compare with models and database used for FLUKA simulations. based on MG5220-S grade WP11 annual meeting – GSI, Dec 4th 2014

A closer look inside the code (I) ----------------------------------------------------------------------- block data scdata … data irmat/9/ Reference data at pRef=450Gev data (mname(i),i=1,nrmat)/ 'Be', 'Al', 'Cu’, 'W', 'Pb', 'C', 'C2’, 'MoGr', 'CuCD'/ data (anuc(i),i=6,nrmat)/ 12.01d0, 12.01d0, 14.81d0, 24.14d0/ data (zatom(i),i=6,nrmat)/ 6d0, 6d0, 7.38d0, 11.8d0/ data (rho(i),i=6,nrmat)/ 1.67d0, 4.52d0, 2.65d0, 5.4d0/ data (radl(i),i=6,nrmat)/ 0.2557d0, 0.094d0, 0.13878d0, 0.04801d0/ data (emr(i),i=6,nrmat)/ 0.25d0, 0.25d0, 0.295d0, 0.347d0/ data (exenergy(i),i=6,nrmat)/ 78e-9, 78.0e-9, 92.22e-9, 147.15e-9/ Atomic properties WP11 annual meeting – GSI, Dec 4th 2014

A closer look inside the code (II) … ! All cross-sections are in barns, nuclear values from RPP at 20geV ! Coulomb is integerated above t=tLcut[Gev2] (+-1% out Gauss mcs) ! ! in Cs and CsRef, 1st index: Cross-sections for processes, 2nd index: Material ! 0:Total ! 1:absorption ! 2:nuclear elastic ! 3:pp or pn elastic ! 4:Single Diffractive pp or pn ! 5:Coulomb for t above mcs data csref(0,8),csref(1,8),csref(5,8)/0.476d0, 0.309d0, 0.012d-2/ data csref(0,9),csref(1,9),csref(5,9)/0.657d0, 0.416d0, 0.027d-2/ ------------------------------------------------------------------------------ Total Inelastic Rutherford scattering Changes done in other parts of the code accordingly WP11 annual meeting – GSI, Dec 4th 2014

SixTrack simulation setup Energy: 7 TeV Beam 1, Hor. halo Statistics: 6.4 x 106 SixTrack particles Nominal 7 TeV optics and post LS1 layout Collimator settings at 7 TeV [σ] IR7 TCP 6 TCSG 7 TCL 10 IR6 7.5 TCDQ 8 IR3 15 18 20 IR1/5 TCT 8.3 IR2/8 25 Simulated scenarios: Reference case: no advanced collimator. TCPs and TCSGs made of CFC Case 1: only TCSGs in IR7 replaced Case 2: TCSGs in IR7 + TCP.C6L7.B1 replaced More relevant case to address impedance issue WP11 annual meeting – GSI, Dec 4th 2014

Beam loss distribution in LHC MoGR CuCD CFC As expected No relevant change in cleaning (affected mainly by TCPs in IR7) WP11 annual meeting – GSI, Dec 4th 2014

Losses in TCSGs in IR7 (I) First two TCSG more loaded than in CFC case Distribution of losses in downstream TCSGs influenced by different scattering behavior of the different materials More particle absorbed in CuCD according to higher density WP11 annual meeting – GSI, Dec 4th 2014

Losses in TCSGs in IR7 (II) + 10-15% losses in advanced collimators Without accounting for additional factor 2 from HL-LHC beam intensity, the load on collimators by beam impact should be still in line with dynamic deformation limits (to be confirmed by FLUKA and AUTODYN simulations for failure scenarios) WP11 annual meeting – GSI, Dec 4th 2014

Inelastic interaction distribution Distribution of absorbed particles along the length of the most loaded TCSG in IR7 WP11 annual meeting – GSI, Dec 4th 2014

Losses in other collimators Losses decreased in all system (momentum cleaning, dump, IR1/5 triplet protection...) Collimators globally more efficient! WP11 annual meeting – GSI, Dec 4th 2014

Summary and Outlook Importance of collimation in the LHC upgrade remarked. Fast failure scenarios reviewed and updated with more realistic conditions to use in the simulations: discussed TCTs, TCSG studies ongoing. Impacts for energy deposition studies now available for several scenarios. SixTrack collimator material database updated with two novel composites: MoGr and CuCD. Preliminary results from simulations with new material collimators in line with expected cleaning efficiency. More materials will be included soon in the database (ex: MoGr Mo-coated). New inputs for future collimator design provided. Energy deposition studies and thermo-mechanical simulations will be performed in the coming months. WP11 annual meeting – GSI, Dec 4th 2014

Thank you for your attention

Backup slides WP11 annual meeting – GSI, Dec 4th 2014

β* reach in IP5 for B1 β* reach in IP5 for different possible optics in the scenario post LS1: Courtesy of D. Mirarchi

Summary of collimator settings Simulated scenarios (E=7 TeV) Collimator half gap Nominal optics HL-LHC optics B2 ATS 2015 B2 nom. B1 nom. B2 HL-LHC 1 HL-LHC 2 HL-LHC 3 IR7 TCPs 5.7 TCSGs 7.7 TCLs 10.5 IR6 TCSG.4R6 8.5 TCDQAs 9.0 IR3 15.0 18.0 20.0 IR1/5 TCTs 7.9 IR2/8 30 Expected integrated losses on TCT.4R5 (B2) Expected integrated losses on TCT.4L1 (B1) Nom. B2 only secondary halo  180 degree (good) phase advance between dump kicker and IR6 protection 3e9 “real protons” (1.7e11p per bunch) Safe! 2e9 “real protons” (2.2e11p per bunch) Safe! 2e10 “real protons” (2.2e11p per bunch) fragment ejection! 2e11 “real protons” (2.2e11p per bunch) > 5th axis limit!! 8e9 “real protons” (1.7e11p per bunch very optimistic!!) plastic deformation! 9e8 “real protons” (1.7e11p per bunch) Safe! A priori, only secondary halo for this case Beam 2 is the most critical one! CollUSM - 19.09.2014

Impact parameter distribution Nominal 7 TeV optics B2 (IR1/5 TCT @ 10 In this case only secondary halo particles are intercepted by TCTH.4R5.B2 due to good phase advance (180°) from the MKD. Primary halo particles Secondary halo particles CollUSM - 19.09.2014

Impact parameter distribution HL-LHC optics B2 (IR1/5 TCT @ 7.9 σ) Primary halo particles Secondary halo particles CollUSM - 19.09.2014

Preliminary results from case 2 Losses on IR7 TCSGs + TCP.C6L7 after material replacement WP11 annual meeting – GSI, Dec 4th 2014