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Ionizing Radiation Estimates for the CLIC Main and Drive beams

Ionizing Radiation Estimates for the CLIC Main and Drive beams. Sophie Mallows, Thomas Otto. Questions. What are the consequence of beam loss ? radiation damage electronics malfunctions activation and exposure of personnel Simulations ( Fluka 2008) were made for absorbed dose D

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Ionizing Radiation Estimates for the CLIC Main and Drive beams

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  1. Ionizing Radiation Estimates for the CLIC Main and Drive beams Sophie Mallows, Thomas Otto CLIC MDI MEETING

  2. Questions What are the consequence of beam loss ? radiation damage electronics malfunctions activation and exposure of personnel Simulations (Fluka 2008) were made for absorbed dose D fluenceF of hadrons with E > 20 MeV, neutron fluence ambient dose equivalent H*(10) from activated material CLIC MDI MEETING

  3. How muchbeamloss do magnets survive ? • Crudebeamloss estimations: • FromBeamdynamics: (est. Daniel Schulte)Fractionalloss 1 E-3 over main beam (2000 Quadrupoles) Assumedequal distribution (certainlywrong): 5E-8/mFractionalloss 1 E-3 in each drive beam section (800 QP) • approximatelyequivalent to those of beamgasscattering • Radiation damage to QP magnetsLessthan 1 MGy per yearwillconservatively assure survival of magnetinsulation over lifetime of accelerator Use FLUKA to simulatelosses and calculateabsorbed doses in coils CLIC MDI MEETING

  4. Representation in Simulation Drive Beam CLIC MDI MEETING

  5. Example in Drive Beam 2.4 GeV Lost before QP 1. Find maximum absorbed dose in magnetic coil region per lost electron 2. Calculate no. of lost electrons required to produce 1 MGy 3.This number is presented as a fraction of the beam, assuming: Continuous Running for 180 days of the year at 1.16E12 per bunch train, 50 hz - main beam 1.54E14 per bunch train , 50 hz – drive beam CLIC MDI MEETING

  6. BeamLossLimits - Damage to QP- Results:PermittedFractionalLosses DB 2.4 GeV 0.24 GeV 9 GeV 1.5 TeV All permitted fractional losses higher than beam dynamics limits Magnet coil insulations appear to be safe in CLIC CLIC MDI MEETING

  7. How much beam loss does electronics survive ? Damage Mechanism Quantified Same Bulk damages as 1 MeV neutrons 1 MeV-neutron equivalent fluence Absorbed dose in Gy Probabilistic- increases with increasing exposure to the radiation fluence of particles with E > 20 MeV, ‘20 MeV-hadronfluence’ Cumulative Effects Lattice Displacement (non ionising energy losses) The Total Ionizing Dose (TID) Single Event Effects (SEEs) Plus, what is the dose rate in the tunnel during technical stops and shutdowns ? CLIC MDI MEETING

  8. Refined Geometrical Model Based on information from A. Samoshkin, Nov 2009 DB Cross Section MB Cross Section Visualized using ‘Flair’ AS cross section Cu Cu (half density) SiC girder under all of DB, and MB AS’s, Support for MB QPs unknown CLIC MDI MEETING

  9. Main beam Layout at 9 GeV Visualized using Simple Geo TYPE 0 TYPE 1 TYPE 0 TYPE 1 Main beam Module sequence for 9 GeV: Type 1,0,1,0,1,0 ….etc. CLIC MDI MEETING

  10. Main beam Layout at 1.5 TeV Visualized using ‘Simple Geo’ DRIVE BEAM Main beam Module sequence for 1.5 TeV: Type 4,0,0,0,0,0,0,0,0,4,0,0,0,0,0,0,0,0…. MAIN BEAM Visualized using Flair TYPE 4 TYPE 0 TYPE 0 MAIN BEAM DRIVE BEAM CLIC MDI MEETING

  11. Magnet / Electronics damageMB 1.5 TeV, Annual Absorbed Dose in Tunnel Electronics Magnets Averaged Over 25 Modules High High Medium Low NORMALISATION: 180 days ,1.16E12 per bunch train, 50hz, Losses 5E-8 m-1 CLIC MDI MEETING

  12. Ambient Dose Equivalent Rate from ActivationMB 1.5 TeV, H*(10) After 1st yr operation Averaged over 3 modules 4h Cooling 1 Week Cooling 4 months Cooling mSv h-1 IRRADIATION: 180 days, 1.16E12 per bunch train, 50hz with losses 5E-8 m-1 CLIC MDI MEETING

  13. Electronics damageMB 1.5 TeV, 1 MeV neutron equivalent fluence Averaged Over 3 Modules High Medium Low NORMALISATION: 180 days ,1.16E12 per bunch train, 50hz, Losses 5E-8 m-1 CLIC MDI MEETING

  14. Electronics Damage MB 1.5 TeV, E > 20MeV Hadronfluence Averaged Over 3 Modules High Medium Low NORMALISATION: 180 days ,1.16E12 per bunch train, 50hz, Losses 5E-8 m-1 CLIC MDI MEETING

  15. Simulations new FLUKA Model MB 1.5 TeV, Absorbed Doses for beam losses in last only 8 modules Gy Beam Loss only over 8 Modules. (4000cm-5600cm) Particle Fluences scored in air-filled cylinder at end of beam line Fluences (next slide) scored here NORMALISATION: 180 days ,1.16E12 per bunch train, 50hz, Losses 5E-8 m-1 CLIC MDI MEETING

  16. Simulations new FLUKA Model MB 1.5 TeV -Fluence Spectra Beam Loss over 8 Modules. Particle Fluences scored in air-filled cylinder at end of beam line Centered on beam line, Rad -70cm. Length 100cm NORMALISATION: 1 loss electron (over last 8 modules) CLIC MDI MEETING

  17. Beam Delivery System andMachine-Detector Interface • The presented simulations were done w/o magnetic fields • Beam loss is assumed to occur everywhere • Only the “next” quadrupole or the immediate vicinity is observed • Is this assumumption true for the BDS / MDI • Transport of secondary particle cascade in magnetic fields of BDI may or may not be important – depends on particle type (see previous fluence spectrum) • Magnetic fields of detectors are certainly important • These questions are presently beyond our capacities and need to be adressed together with BE and PH CLIC MDI MEETING

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