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Energy deposition studies at IR7

Energy deposition studies at IR7. Collimation collaboration meeting 09-05-2005. M. Santana, M. Magistris, A. Ferrari, V. Vlachoudis. Introduction. Motivation. Large Hadron Collider : 27 km cryogenic installation LHC is a proton-proton collider

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Energy deposition studies at IR7

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  1. Energy deposition studies at IR7 Collimation collaboration meeting 09-05-2005 M. Santana, M. Magistris, A. Ferrari, V. Vlachoudis

  2. Introduction

  3. Motivation Large Hadron Collider : 27 km cryogenic installation • LHC is a proton-proton collider • 2 proton beams at 7 TeV of 3×1014 p+ each • stored for 10-20 hours in collision • total stored energy of 0.7 GJ (sufficient to melt 1 ton of Cu) • ~5000 cold magnets • Tiny fractions of the stored beam suffice to quench a superconducting LHC magnet or even to destroy parts of the accelerators. • The LHC collimation system will protect the accelerator against unavoidable regular and irregular beam loss. from MC2005 V. Vlachoudis

  4. Material Density g/cm3 Escaping % Aluminum 2.7 88.8 Beam propagation Beryllium 1.848 97 Core Copper 8.96 34.4 Graphite 1.77 96.4 Diffusion processes 1 nm/turn Titanium 4.54 79.5 Primary halo (p) Secondary halo Example for 1 m long jaws!  p  Tertiary halo Impact parameter ≤ 1 m p e Primary collimator p Secondary collimator Shower e Sensitive equipment Shower Secondary collimators intercept halo --> Shower energy escapes to downstream elements! so then... What happens downstream? Two Stage Cleaning

  5. LHC lattice and optics files V6.5 • Primary and Secondary collimators, Scrapers, Absorbers RR73 Normal operation 0.2 hours beam lifetime --> 4×1011 p/s for 10 s E6 C6 A6 UJ76 IP7 A6 RR77 C6 E6 IR7 layout RADWG-RADMON Workshop Day, CERN 01/12/2004 5

  6. IR7 Geometry RR73 RR77 UJ76 6 RADWG-RADMON Workshop Day, CERN 01/12/2004

  7. Geometry of the dipoles Tesla 14m long objects with a field of 8.3 Tesla: 5mrad bend  ~3cm sagitta. The superconducting dipoles(MB)are made out of 4 straight sections to accommodate the trajectory.

  8. Magnetic field maps • General routine for handling magnetic field maps (Analytic and/or 2D Interpolated) with the use of an external file with a special format • Magnetic field type • CONST Constant field • QUAD 2D Analytic quadrupole field • QUADINT 2D Analytic+Interpolated quadrupole field • INTER2D 2D Interpolated field • Symmetries: • NONE No symmetry • X, Y, Z Symmetrical on plane X, Y, Z (-x  x, …) • XY On both planes XY • XYZ On all planes XYZ • Table with interpolated data (Bx,By,Bz) • Quadrupole analytic description • Origin of the magnetic field map origin • Limiting radius up to where to consider an analytic field • Translation and Rotation of the field map • Field intensity / gradient specified per region or lattice from MC2005 V. Vlachoudis

  9. Magnetic field example MQW – Warm Quadrupole 2D Interpolated Analytic XY Symmetry from MC2005 V. Vlachoudis

  10. Primary Inelastic collisions map • Generated by the COLLTRACK V5.4 program • 3 scenarios: Vertical, Horizontal and Skew • Pencil beam of 7 TeV low-beta beam on primary collimators • 100 turns without diffusion • Impact parameter: 0.0025  • Spread in the non-collimator plane: 200 m • Recording the position and direction of the inelastic interactions • FLUKA source: Force an inelastic interactions on the previously recorded positions Beam Loss Map M. Brugger et al from MC2005 V. Vlachoudis

  11. Execution time Biasing • Importance biasing: radially decreasing • Leading particles biasing • High energy cuts on EMF on regions far away • Weight Windows per region Statistics • 30% on maximum • Linux Cluster • 64 CPU’s @ 3GHz • 1 week run Improvements: • Bias the diffractive/inelasticscattering ratio from MC2005 V. Vlachoudis

  12. Collimators

  13. Collimators Material Choice Not driven so much by the standard collimation but rather by the faulty operations or malfunctions • Worst Accident scenarios: • Due to a spontaneous rise of one of the extraction kicker modules during the coast, part of the 7 TeV/c beam is spread across the front of a collimator jaw. • Faulty kick by the injection kicker where a full batch of protons hit the front of a collimator jaw at 450 GeV/c • Very fast absorptions of part of the proton energy: • Instantaneous temperature rise • Thermally induced stresses (overheating/melting) • Limits material choice which can be used and still be compatible with other machine requirements. • FLUKA-2002-4A.Fasso, A.Ferrari, J.Ranft, P.R.Sala Proceedings of the Monte Carlo 2000 Conference, Lisbon, Oct. 23-26 2000, Springer-Verlag Berlin, p 955-960 (2001) from MC2005 V. Vlachoudis

  14. Collimators Criteria: • Primary and secondary collimators are the closest elements to the beam • Activating single scattering for thin layer on jaws • Jaw halfgap / tilt variable during runtime Primaries: Gap: 6  Jaws: C-C Length: 20cm... may be changed to 60 Secondaries: Gap: 7  Jaws: C-C Length: 100cm Absorbers: Gap: 10  Jaws: Cu or W Length: 100cm from MC2005 V. Vlachoudis

  15. Secondary Collimator Maximum Energy density in TCSGA6L1 carbon jaws

  16. Simulations

  17. Input Files • FLUKA input template • Twiss files • Collimator summary • Absorbers summary • Prototype Info Fluka Input (.inp) • LATTICE definitions • Curved Tunnel creation • Magnetic Fields Intensity • Scoring cards mklattic.r BRexx Script Fluka Executable • LATTICE transformations • Dynamic adjustment of collimator gaps Fortran Files • Source routine • Si Damage 1 MeV n eq. • Magnetic Field • History Tracking Simulation Strategy • Dynamic FLUKA input generation with several ad-hoc scripts • Detailed description of 20 prototypes located in a virtual parking zone. • Prototypes are replicated with the LATTICE card, rotated and translated. • Magnetic field maps: Analytic + 2D Interpolated • Dynamic generation of the ARC (curved section) • Optics test: Tracking up to 5 , both vertical / horizontal, reproduce beta function

  18. Automatic Geometry Creation 1. Initial input file template 2. Space Allocation & Geometry Creation 3. Lattice generation 4. Magnetic Fields mapping

  19. Implementation of vertical and horizontal absorbers Geometry Beam profile Like secondary collimator, with Cu jaws and 10 sigma halfwidth z(m)

  20. Steps to launch a simulation Absolute position • 1) Modify active absorbers: Usetwiss/tensigma.dat #icoll Name Material Length Rotation Tilt(jaw1) Tilt(jaw2) Halfgap N_Impacts N_InelInt Impact(av) Impact(sig) # [m] [rad] [rad] [rad] [m] (protons) (protons) [m] [m] 1 TCL.A4R7.B1 CU 0.000 0.1571000E+01 0.000000E+01 -0.1669557E-04 0.3517000E-02 267759 120004 0.8801409E-05 0.2861191E-04 # 1 TCL.A4R7.B1 CU 0.000 0.0000000E+01 0.0000000E+01 -0.1669557E-04 0.1931000E-02 267759 120004 0.8801409E-05 0.2861191E-04 # 1 TCL.A6R7.B1 CU 1.000 0.1571000E+01 0.0000000E+01 -0.1669557E-04 0.1585000E-02 267759 120004 0.8801409E-05 0.2861191E-04 # 1 TCL.A6R7.B1 CU 0.000 0.0000000E+01 0.0000000E+01 -0.1669557E-04 0.3859000E-02 267759 120004 0.8801409E-05 0.2861191E-04 ... twiss/absorber_summary.dat - Each absorber must be defined in both files (inactive absorbers count but not hashed lines). - There cannot be two active replica of the same absorber. 0.1571 = Vertical 0.0000 = Horiz. 1.000 = active 0.000 = inactive # = no line "RCOLLIMATOR" "TCL.A4R7.B1" 0 0 20022.5326 0.00 0.00 0.00 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 "RCOLLIMATOR" "TCL.A6R7.B1" 0 0 20148.3344 0.00 0.00 0.00 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 V6.5_absorbers.b1.phase1.data

  21. Steps to launch a simulation BEAM 7000.0 PROTON SOURCE beam1 *SOURCE A7 *SOURCE B7 ir7.fluka SOURCES="Twiss/beam1.dat Twiss/beam2.dat Twiss/beam1V.dat Twiss/beam1H.dat Twiss/beam1S.dat Twiss/beam1VP.dat Twiss/beam1VPH.dat Twiss/beam1VPS.dat Twiss/beam1VPV.dat Twiss/beam1VS1.dat Twiss/A7.dat Twiss/B7.dat Twiss/nbeam1.dat" run.sh • 2) Modify geometry, activate relevant USRBIN in ir7.fluka • USRBIN -39.0 must always be active. • 3) Check for errors in prototypes etc.: • $ fluka.r -m ir7.fluka ir7.i • $ mcnpx ip i=ir7.i • 4) Select appropiate beam file: • Check ir7.fluka: • Check run.sh to include that beam:

  22. Steps to launch a simulation File with formatted results $ usbsuw to summarize $ usbfuf to format • 5) IF a new prototype has been designed, include it in prototype.pos: • 6) Compile geometry --> ir7.inp: • $ make proper • $ make • 7) Check correctness of ir7.inp: • Check number and type of absorbers ir7.inp. • Make plots of newly introduced elements: • $ flukaplot.r ir7.inp flukair7 • 8) Make a test run: • Check results and speed. • Check lattice tables: • $ EnLattice.pl < 'ir7.inp' 'usrbinf_39' '1' • 9) RUN and analyze. # Absorber (like Hybrid) TCL 0 0 TCL2 -2000.0 0.0 5060.0 100.0 - # prototype.pos One or two beams (normalization) 1 or 2 beams

  23. Correction of beam direction. x Only primaries are affected 85%inelastic scattering (minor consequences) 15%diffractive scattering (deviated and partially lost) y 0.5 mrad rotation x z 40% more dose in MQTLH, but still below limit Much higher dose in the curved section, but still well below the limit

  24. Results: warm elements

  25. Preliminary results for the straight section (corrected beam) Total energy deposited in the MBWB6L: Corrected beam: 28.4 kW (Uncorrected beam: 37 kW) Energy deposited in the TCSGA6L1: Total energy: 20 kW (Uncorrected beam: 22.6 kW ) Energy in both jaws: 5.1 kW (Uncorrected beam: 1.02 kW ) Hot spot with no physical meaning, due to the beam error

  26. Heat in the finger collar of the TCSGA6L1 80.4 W 16.9 W

  27. Energy deposition in flanges W/cm3 TCSGA6L1 70 W 457 W <-front back-> 22 W 85 W

  28. Passive absorber • Most of the radiation deposited in the MBW insulator comes from inside the beam pipe. • The efficiency of the absorber strongly depends on the inner radius. Fe absorber. 2 cm radius (pipe is 4 cm) Ideal absorber. Pipe size. ~ 1 MGy/y 5-10 MGy/y • Need for smaller radius. Cu absorber? Ideas?

  29. Results: cold elements

  30. Implementation of vertical and horizontal absorbers TCL.F6R7.B1 Beam 2 Beam 1 TCL.A4R7.B1 6 candidate absorbers in straight section TCL.E6R7.B1 s= 20213 TCL.A6R7.B1 s= 20148.33 4 Finally selected TCL.A7R7.B1 s= 20251.65 2 candidate absorbers before curved section TCL.C6R7.B1 s= 20179.29 TCL.B7R7.B1 s= 20236.65 1 Finally selected.

  31. 4+1: A6vC6hE6vF6h-A7h Number of simulations: 442 ******* Straight Section ************* ** * MQTLHA6R ******************* * max heat in coil:........ 0.759 mW/cm3 (+- 19.9 %) * Total heat in the coil:.. 0.35 W (+- 7.00 %) * heat in MQ:.............. 1.22 W (+- 4.10 %) ** * MQ6 group ****************** MQTLHA6R 1.22 (+- 4.10 %) W MQTLHB6R 0.40 (+- 5.37 %) W MQTLHC6R 0.26 (+- 6.13 %) W MQTLHD6R 0.19 (+- 7.87 %) W MQTLHE6R 0.14 (+- 9.74 %) W MQTLHF6R 0.13 (+- 9.93 %) W ------------------------------------ TOTAL 2.07 (+- 2.83 %) W ******* Curved Section **************** Total energy in coils and magnets of MQ[7-11]R. MQ7 | max: 0.286 (+-99.0%) | 1.796e-01 +- 30% | Total: 0.433 W +- 18.0 % MQ8 | max: 0.699 (+-82.8%) | 1.193e-01 +- 47% | Total: 0.227 W +- 26.4 % MQ9 | max: 0.245 (+-65.5%) | 1.474e-01 +- 55% | Total: 0.264 W +- 33.2 % MQ10 | max: 0.132 (+-99.0%) | 3.124e-02 +-100% | Total: 0.074 W +- 46.5 % MQ11 | max: 0.284 (+-99.0%) | 1.566e-02 +-100% | Total: 0.034 W +- 49.2 % Total energy in coils and magnets of MB[A-B][8-11]R. MBA8R | 1:inner_coil 1.120e-01 +- 30% | 1:outer_coil 5.637e-02 +- 28% | max: 0.143 (+-98.2%) | MBB8R | 2:inner_coil 8.321e-01 +- 17% | 2:outer_coil 4.208e-01 +- 17% | max: 0.400 (+-85.5%) | MBA9R | 3:inner_coil 3.937e-01 +- 24% | 3:outer_coil 2.060e-01 +- 24% | MBB9R | 4:inner_coil 3.069e-01 +- 30% | 4:outer_coil 1.721e-01 +- 29% | MBA10R | 5:inner_coil 3.439e-03 +- 58% | 5:outer_coil 1.343e-03 +- 59% | MBB10R | 6:inner_coil 2.132e-04 +- 69% | 6:outer_coil 4.892e-05 +- 69% | MBA11R | 7:inner_coil 2.003e-01 +- 37% | 7:outer_coil 1.135e-01 +- 36% | MBB11R | 8:inner_coil 1.085e-01 +- 42% | 8:outer_coil 6.023e-02 +- 42% |

  32. Radiation in the MBA8

  33. Heat spikes in MB's

  34. Radiation in the MQ's 1W +- 0.5 W 0.01W +- 0.01 W 1W +- 0.5 W mW/cm3

  35. Comparison between A7h and B7h Tertiary halo Part of the beam halo will interact with the absorbers and generate a hadronic shower => energy deposition in the cold magnets The contribution from B7h will be 15% higher than A7h, but still at an acceptable level. Peak values in MQ7: A7h => 0.22 mW/cmc (*) B7h => 0.26 mW/cmc (*) (*) values refer to 1 proton interacting out of 10,000 lost in TCP. Error is below 6%.

  36. Comparison between A7h and B7h • Simulations were run with corrected beam. • The accuracy of the magnetic field in the MB was improved. • Low energy photons were fully simulated. from PAC2005 M. Santana et al.

  37. Comments

  38. Simulation accuracy. Sources of error - Physics modeling: • Uncertainty in the inelastic p-A extrapolation cross section at 7 TeV lab • Uncertainty in the modeling used Factor ~1.3 on integral quantities like energy deposition (peak included)while for multi differential quantities the uncertainty can be much worse. - Layout and geometry assumptions: It is difficult to quantify, experience has shown that a factor of 2 can be a safe limit. - Beam grazing at small angles on the surface of the collimators: Including that the surface roughness is not taken into account a factor of 2 can be a safe choice. - Safety factor from the tracking program COLLTRACK is not included! from MC2005 V. Vlachoudis

  39. Some facts ... - Challenge: • 'Filter twice 450 kJ' in such a way that superconducting elements get less than 5 mW/cm3! • Track showers along 1.5 km of tunnel and build up statistics with rare occurring events. - Resources: Over 7 years of equivalent CPU-(2.8 GHz) over 15 months in a 3 man-year effort. - Models and scripts: one of the most complex simulations in FLUKA.

  40. Related works: UJ & RR's electronics protection K. Tsoulou

  41. No Absorber vs. Absorber (tunnel) Flux (cm-2/y) Dose (Gy/y) UJ76 RR73 RR77 NoAbsorbers A6vC6Eh6v Absorbers beam1 beam2 A6v E6v C6h E6v A6v C6h Mean values ± 2m horizontally and ± 1m vertically. 41 RADWG-RADMON Workshop Day, CERN 01/12/2004

  42. Three Absorber Case for UJ76 Dose (Gy/y) Dose (Gy/y) Doses in racks ≤ 5 Gy Similar to NoAbsorber case ! 42 RADWG-RADMON Workshop Day, CERN 01/12/2004

  43. Related works: Ozone production in IR7. Accident case studies,... A. Pressland

  44. Introduction • Radiation induced production of O3 around IP7. • dose estimates provided by Fluka • assumed 4.1  1016 lost protons per year. • assumed all Fluka energy loss in air is ionizing. • Enclosures around regions of high dose (O3 concentration) • enclosures seal the tunnel in areas where the ozone • voided independently of the main tunnel • air corridor to allow passage of tunnel air towards TU76

  45. Tunnel Section

  46. Energy scorings • Annual dose (GeV/cm3) based 4800 beam-hours • Complient with the standard 104 – 105 Gy/year

  47. Calculation (1) Fasso et el (1982) LEP Note 379 gives the following differential equation I = ionizing energy deposited in air per unit time, in eVcm-3s-1 G = number of ozone molecules formed, in eV-1 (7.4  10-2 eV-1)  = dissociation constant for ozone, in s-1 (2.3  10-4 s-1) N = concentration of ozone at time t, in cm-3 k = decomposition constant, in eV-1cm3 (1.4  10-16 eV-1cm3) Q = ventilation rate, in cm3s-1 V = irradiated volume, in cm3 Integration leads to the following concentration kinetics: dissociation ventilation formation decomposition

  48. Calculation (2) More useful steady state formulation in a tunnel average energy , Iave, is deposited per unit time air circulates with speed v ms-1 length z of tunnel is irradiated This is a special case of the previous equation where the concentration N cm-3 increases with distance z traversed and air traverses a length z meters of tunnel in z/v seconds accumulating a concentration N(z) molecules of ozone

  49. Results Tunnel Encl. 1 Encl. 2 NO3 (ppm) 4.63  10-4 8.9 10-3 4.3  10-3 • Steady state results for air exiting regions • Assumed ventilation rates • 10 m3s-1 for the main tunnel • 0.2 m3s-1 for the enclosures • Parts per million conversion requires • air density of 1.202 kg m-3 • molecular weight of 28.95 g mol-1 • Avogadro constant NA = 6.022  1023

  50. Results Concentration kinetics using averaged dose assumes ‘magic ventilation’ where air is not considered to travel to the ventilation point through a radiation environment. only useful to compare growth rates etc 5.1 10-2 ppm 2.5 10-2 ppm 2.3 10-4 ppm 300 mins 300 mins 25 mins Tunnel Enclosure 1 Enclosure 2

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