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CNGS Run 2007: Radiation Issues

CNGS Run 2007: Radiation Issues. Edda Gschwendtner On behalf the CNGS Secondary Beam Working Group. Outline. CNGS Overview Run 2007 Radiation Issues during the Run Expected Radiation Levels Summary. A long base-line neutrino beam facility (732km) send n m beam produced at CERN

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CNGS Run 2007: Radiation Issues

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  1. CNGS Run 2007:Radiation Issues Edda Gschwendtner On behalf the CNGS Secondary Beam Working Group

  2. Outline • CNGS Overview • Run 2007 • Radiation Issues during the Run • Expected Radiation Levels • Summary E. Gschwendtner, AB/ATB

  3. A long base-line neutrino beam facility (732km) sendnm beamproduced at CERN detect nt appearancein OPERA experiment at Gran Sasso CNGS (CERN Neutrino Gran Sasso)  direct proof ofnm-ntoscillation (appearance experiment) Task for CERN: produce intense nm beam towards Gran Sasso E. Gschwendtner, AB/ATB

  4. CNGS Proton Beam Parameters Expected beam performance: 4.5 x 1019 protons/year on target E. Gschwendtner, AB/ATB

  5. CNGS Challenges • High Intensity, High Energy Proton Beam • Tune, tune, tune • Induced radioactivity • In components, shielding, fluids, etc… • Intervention on equipment ‘impossible’ • Remote handling by overhead crane • Replace broken equipment, no repair • Human intervention only after long ‘cooling time’ • Design of equipment: compromise • E.g. horn inner conductor: for neutrino yield: thin tube, for reliability: thick tube • Intense Short Beam Pulses, Small Beam Spot • Interlock, interlock, interlock • Thermo mechanical shocks by energy deposition (designing target rods, thin windows, etc…)  most challenging zone:Target Chamber (target–horn–reflector) E. Gschwendtner, AB/ATB

  6. SPS protons LHC CNGS pions kaons muons neutrinos Neutrinos to Gran Sasso E. Gschwendtner, AB/ATB

  7. 2.7m 43.4m 100m 1095m 18m 5m 67m 5m Pit 2 Pit 1 TBID (multiplicity) Muon Detectors CNGS Layout p + C (interactions) p+, K+ (decay in flight) m+ + nm E. Gschwendtner, AB/ATB

  8. CNGS Target Chamber Installation of target magazine (4 in-situ spares) Installation of Focusing magnet (‘Horn’) E. Gschwendtner, AB/ATB

  9. 270cm 60cm 11.25cm Muon Monitors LHC type Beam Loss Monitors • Stainless steel cylinder • Al electrodes, 0.5cm separation • N2 gas filling • 2x41 fixed monitors + 2x1 movable Online feedback to neutrino beam quality (sensitivity to any misalignment of beam vs. target vs. horn, horn/reflector currents, etc…) E. Gschwendtner, AB/ATB

  10. Tue, 2 Oct, 17:04:25 nm CC interaction Muon 7GeV/c CNGS Run 2007 (17/09-22/10/2007) Smooth start-up, very good beam performance • 38 OPERA events in bricks • More than 400events from interactions outside OPERA detector E. Gschwendtner, AB/ATB

  11. CNGS Run 2007 (17/09-22/10/2007) • Smooth start-up, very good beam performance • 38 OPERA events in bricks • More than 400 events from interactions outside OPERA detector • Successive failures in the ventilation system • Strong efforts made by TS/CV to save the situation • Physics run stopped on Monday 22 October 2007, 5 days ahead of time. • Failures in the ventilation system control electronics that blocked switching to access mode in a safe manner  intolerable for an INB facility E. Gschwendtner, AB/ATB

  12. Ventilation Units Service Gallery He tube 1 reflector He tube 2 decay tube target horn Proton Beam Line Target Chamber Temperature Probes CNGS Electronics Layout Radiation ‘safe’ area for electronics TSG4 TCV4 …electronics equipment E. Gschwendtner, AB/ATB

  13. Unit 232 TSG44 Ventilation System for CNGS Surface TSG4 TCV4 E. Gschwendtner, AB/ATB M. Batz, SBWG, 31.10.07

  14. Incidents of CNGS Ventilation System 3 x Incidents: SEU in ventilation electronics: Loss of Control and Communication • & 2.) Electronics of PLC Com, PLC unit 237 and remote I/O in unit 232 failed, • Repeater in profibus failed  causes units in TCV4 and units 519 and 231 to stop. Surface TCV4 TSG4 M. Batz, SBWG, 31.10.07 E. Gschwendtner, AB/ATB

  15. Simulation environment: Unified approach for physics (neutrino and muon fluxes), engineering (power deposition), prompt (radiation damage) dose rates residual (maintenance and interventions) dose rates Reasonably detailed geometry down to muon pits each BLM simulated in detail Service and connection galleries empty no rack, no ventilation unit, no piping, no ducts, no doors, no dividing walls  should be conservative Common effort of AB/ATB, RP, INFN Available outputs for radiation: Absorbed and equivalent dose maps (prompt and residual) High energy hadron fluences 1 MeV neutron equivalent fluences (for Si damage) Particle spectra at several locations CNGS Radiation Levels Calculations with FLUKA M. Brugger, A. Ferrari, L.Sarchiapone, AB/ATB E. Gschwendtner, AB/ATB

  16. Expected Dose Levels Gy/yr for a nominal CNGS year of 4.5 1019 pot ‘Safe’ Area, Electronics for AB, IT, TS… 0.1-1 Gy/yr Electronics of Ventilation Units must be moved! Ventilation Units Electronics for CV, crane, fire detection TSG4 TCV4 TCC4 M. Brugger, A. Ferrari, L.Sarchiapone, 28.11.07, FLUKA E. Gschwendtner, AB/ATB

  17. ‘Safe’ Area for Electronics Control Equipment in the CNGS Area: Ventilation System, Crane, Fire Detectors, Transformers, Battery Charger, Switchboard, Ethernet, Control for Target, Shutter, Decay Tube, Temperature Probes, Horn & Reflector Cooling system, Radiation Detector, Beam Instrumentation (BLMs, TBID, BFCT, BPMs) Electronics Racks Transformer Battery charger Switchboard TSG4 E. Gschwendtner, AB/ATB

  18. 109-1010 1MeV n eq./cm2/yr Expected Neutron Fluence 1 MeV eq. neutron fluence (cm-2 yr-1) for a nominal CNGS year of 4.5 1019 pot TSG4 TCV4 TCC4 M. Brugger, A. Ferrari, L.Sarchiapone, 28.11.07, FLUKA E. Gschwendtner, AB/ATB

  19. 107-108 hadrons/cm2/yr Expected High Energy Hadron Fluence Energetic (> 20 MeV) hadron fluence (cm-2 yr-1) for a nominal CNGS year of 4.5 1019 pot TSG4 TCV4 TCC4 M. Brugger, A. Ferrari, L.Sarchiapone, 28.11.07, FLUKA E. Gschwendtner, AB/ATB

  20. Radiation Measurements • RadMon Monitors (T. Wijnands) • TLDs (SC/RP) • PMI detectors (SC/RP) TCV4 TSG4 (vent. units) ‘safe’ area for electr. X X proton beam target X Measurements only during last day of operation: 7.2·1016 pot E. Gschwendtner, AB/ATB

  21. Summary I • Detailed analysis and comparison between the simulations and measurements ongoing • The numbers basically agree: • Some better understanding of RadMon monitor sensitivity needed. • No major changes in simulations (updated geometry) with respect to previous calculations  confirmed by measurements E. Gschwendtner, AB/ATB

  22. All installed electronics are COTS (most not even rad hard) Nearest completely safe area is ~1000m away For much of the electronics there are technical reasons to limit the cable lengths to <100m. For MTBF > 1year Area with electronics must be shielded (gain factor >104 ?!) Or move electronics to storage area and add shielding For both cases: Critical equipment for access must be moved to the surface (mainly ventilation parts) Redundancy and preventive maintenance and actions Radiation monitoring Summary II  CNGS must be ready for beam on 28 May 2008 E. Gschwendtner, AB/ATB

  23. Spare Slides E. Gschwendtner, AB/ATB

  24. High energy hadron levels, TCV4 Energetic (> 20 MeV) hadron fluence (cm-2 yr-1) for a nominal CNGS year of 4.5 1019 pot: vertical cut along TCV4 M. Brugger, A. Ferrari, L.Sarchiapone, 28.11.07, FLUKA E. Gschwendtner, AB/ATB

  25. Example Expected Particle Spectra in TSG4 Neutron (black), photon (purple), andelectron (red)spectra in the service gallery M. Brugger, A. Ferrari, L.Sarchiapone, 28.11.07, FLUKA E. Gschwendtner, AB/ATB

  26. Possible solutions Required reduction factor: ~104 Typical shielding: ~1.6m Fe + ~1m concrete but hermetic! • leave electronics in place, add shielding E. Gschwendtner, AB/ATB

  27. Possible solutions... 2) use existing tunnel (TSG40) to house all the electronics • TSG40 is foreseen as garage to store broken horn/reflector/target during the lifetime of the facility. Alternative storage areas must be found in that case.... E. Gschwendtner, AB/ATB

  28. CNGS 07 Commissioning Week 38-40 First brick event # pot/extr. 1.84 E13 pot/extr. 2 Oct. 07: 1.84E13 pot (max. 2006: 1.77E13 pot) With reference setting:  increasing intensity • Setting-up of secondary beam: • Alignment beam vs. target vs. horn • Calibration of TBID • Study behavior for neutrinos/antineutrinos • Setting up of SC • Interlock tests • horn/reflector test 24 hr run MD (+strip-line cable) 2 E12 pot/extr. Time 1 Oct 07 28 Sept 07 21 Sept 07 Total: ~5E16 pot E. Gschwendtner, AB/ATB

  29. CNGS Physics Run 2007 Total: 7.9 E17 pot 6.3E17 pot 8.4E16 pot 2 E13 pot/extr. First brick event 7.2E16 pot Loss of ventilation control  Stop beam Modifications in ventilation control 12 Oct 07 19 Oct 07 5 Oct 07 Stop CNGS: non-standard mode of operation (access) not possible in an INB controlled facility E. Gschwendtner, AB/ATB

  30. On-line Muon Profiles after Optimizations 2 x 1.4E13pot/extr. Horizontal, pit1 Horizontal, pit2 • Pit 1: sensitive to target vs horn alignment • Pit 2: sensitive to beam vs target alignment Vertical, pit1 Vertical, pit2 E. Gschwendtner, AB/ATB

  31. Radiological Issues • Beam on: • < 100Sv/h outside the horn shielding • < 2Sv/h in service gallery • Beam off immediately afterwards • 100mSv/h For intervention: dose rate < 2mSv/intervention (CERN rule) Examples: • 1 week shutdown to change a motor of the target • 1 month shutdown to exchange the horn • Only possible because most is remotely handled! Access is controlled with ‘radiation veto’! E. Gschwendtner, AB/ATB

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