CNGS Run 2007 Radiation Issues Edda Gschwendtner On

CNGS Run 2007: Radiation Issues Edda Gschwendtner On behalf the CNGS Secondary Beam Working Group 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB

Outline • • • 6 th LHC Radiation Workshop, 29 November 2007 CNGS Overview Run 2007 Radiation Issues during the Run Expected Radiation Levels Summary E. Gschwendtner, AB/ATB 2

CNGS (CERN Neutrino Gran Sasso) – – – A long base-line neutrino beam facility (732 km) send nm beam produced at CERN detect nt appearance in OPERA experiment at Gran Sasso direct proof of nm - nt oscillation (appearance experiment) Task for CERN: produce intense nm beam towards Gran Sasso 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 3

CNGS Proton Beam Parameters Beam parameters Nominal energy [Ge. V] Normalized emittance [mm] Emittance [mm] Momentum spread Dp/p # extractions per cycle Nominal CNGS beam 400 H=12 V=7 H=0. 028 V= 0. 016 0. 07 % +/- 20% 2 separated by 50 ms Batch length [ms] 10. 5 # of bunches per pulse 2100 Intensity per extraction [1013 p] 2. 4 Bunch length [ns] (4 s) 2 Bunch spacing [ns] 5 Beta at focus [m] Beam sizes at 400 Ge. V [mm] Beam divergence [mrad] hor. : 10 ; vert. : 20 0. 5 mm hor. : 0. 05; vert. : 0. 03 Expected beam performance: 4. 5 x 1019 protons/year on target 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 4

CNGS Challenges • High Intensity, High Energy Proton Beam – 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 – Thermo mechanical shocks by energy deposition (designing target rods, thin windows, etc…) most challenging zone: Target Chamber (target–horn–reflector) 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 5

SPS protons LHC pions kaons CNGS muons neutrinos 6 th LHC Radiation Workshop, Neutrinos 29 November 2007 to Gran Sasso E. Gschwendtner, AB/ATB 6

CNGS Layout 2. 7 m 43. 4 m 100 m 1095 m 67 m 5 m Pit 2 Muon Detectors (interactions) p+, 6 th LHC Radiation Workshop, 29 November 2007 5 m Pit 1 TBID (multiplicity) p+C 18 m K+ (decay in flight) m+ + nm E. Gschwendtner, AB/ATB 7

CNGS Target Chamber Installation of target magazine (4 in-situ spares) Installation of Focusing magnet (‘Horn’) 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 8

Muon Monitors LHC type Beam Loss Monitors 60 cm • • Stainless steel cylinder Al electrodes, 0. 5 cm separation N 2 gas filling 2 x 41 fixed monitors + 2 x 1 movable 270 cm 11. 25 cm Online feedback to neutrino beam quality (sensitivity to any misalignment of beam vs. target vs. horn, horn/reflector currents, etc…) 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 9

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 Tue, 2 Oct, 17: 04: 25 nm CC interaction 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB Muon 7 Ge. V/c 10

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 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 11

CNGS Electronics Layout Radiation ‘safe’ area for electronics Ventilation Units TSG 4 Service Gallery TCV 4 Proton Beam Line target horn He tube 1 reflector He tube 2 decay tube Target Chamber …electronics equipment 6 th LHC Radiation Workshop, 29 November 2007 Temperature Probes E. Gschwendtner, AB/ATB 12

Ventilation System for CNGS Unit 232 TSG 44 Surface TCV 4 6 th LHC Radiation Workshop, 29 November 2007 TSG 4 E. Gschwendtner, AB/ATB M. Batz, SBWG, 31. 10. 07 13

Incidents of CNGS Ventilation System 3 x Incidents: Surface TCV 4 SEU in ventilation electronics: Loss of Control and Communication 1. & 2. ) Electronics of PLC Com, PLC unit 237 and remote I/O in unit 232 failed, 3. Repeater in profibus failed causes units in TCV 4 and units 519 and 231 to stop. TSG 4 M. Batz, SBWG, 31. 10. 07 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 14

CNGS Radiation Levels Calculations with FLUKA M. Brugger, A. Ferrari, L. Sarchiapone, AB/ATB 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 Me. V neutron equivalent fluences (for Si damage) Particle spectra at several locations 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 15

Expected Dose Levels Gy/yr for a nominal CNGS year of 4. 5 1019 pot ‘Safe’ Area, Electronics for AB, IT, TS… Electronics for CV, crane, fire detection 0. 1 -1 Gy/yr Electronics of Ventilation Units must Units be moved! TSG 4 TCV 4 TCC 4 M. Brugger, A. Ferrari, L. Sarchiapone, 28. 11. 07, FLUKA 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 16

‘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 Battery charger TSG 4 6 th LHC Radiation Workshop, 29 November 2007 Transformer Switchboard E. Gschwendtner, AB/ATB 17

Expected Neutron Fluence 1 Me. V eq. neutron fluence (cm-2 yr-1) for a nominal CNGS year of 4. 5 1019 pot 109 -1010 1 Me. V n eq. /cm 2/yr TSG 4 TCV 4 TCC 4 M. Brugger, A. Ferrari, L. Sarchiapone, 28. 11. 07, FLUKA 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 18

Expected High Energy Hadron Fluence Energetic (> 20 Me. V) hadron fluence (cm-2 yr-1) for a nominal CNGS year of 4. 5 1019 pot 107 -108 hadrons/cm 2/yr TSG 4 TCV 4 TCC 4 M. Brugger, A. Ferrari, L. Sarchiapone, 28. 11. 07, FLUKA 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 19

Radiation Measurements TCV 4 ‘safe’ area for electr. TSG 4 (vent. units) X X proton beam • Rad. Monitors (T. Wijnands) • TLDs (SC/RP) target X Measurements only during last day of operation: 7. 2·1016 pot • PMI detectors (SC/RP) 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 20

Summary I • Detailed analysis and comparison between the simulations and measurements ongoing – The numbers basically agree: • Some better understanding of Rad. Mon monitor sensitivity needed. • No major changes in simulations (updated geometry) with respect to previous calculations confirmed by measurements 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 21

Summary II • All installed electronics are COTS (most not even rad hard) • Nearest completely safe area is ~1000 m away • For much of the electronics there are technical reasons to limit the cable lengths to <100 m. • For MTBF > 1 year – 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 CNGS must be ready for beam on 28 May 2008 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 22

Spare Slides 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 23

High energy hadron levels, TCV 4 Energetic (> 20 Me. V) hadron fluence (cm-2 yr-1) for a nominal CNGS year of 4. 5 1019 pot: vertical cut along TCV 4 M. Brugger, A. Ferrari, L. Sarchiapone, 28. 11. 07, FLUKA 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 24

Neutron (black), photon (purple), and electron (red) spectra in the service gallery 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB M. Brugger, A. Ferrari, L. Sarchiapone, 28. 11. 07, FLUKA Example Expected Particle Spectra in TSG 4 25

Possible solutions 1) leave electronics in place, add shielding 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB Required reduction factor: ~104 Typical shielding: ~1. 6 m Fe + ~1 m concrete but hermetic! 26

Possible solutions. . . 2) use existing tunnel (TSG 40) to house all the electronics – TSG 40 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. . 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 27

CNGS 07 Commissioning Week 38 -40 First brick event # pot/extr. 1. 84 E 13 pot/extr. 2 Oct. 07: 1. 84 E 13 pot (max. 2006: 1. 77 E 13 pot) With reference setting: increasing intensity Setting-up of secondary beam: -Alignment beam vs. target vs. horn -Calibration of TBID -Setting up of SC -Interlock tests -horn/reflector test -Study behavior for neutrinos/antineutrinos 24 hr run MD (+strip-line cable) 2 E 12 pot/extr. 28 Sept 07 21 Sept 07 1 Oct 07 Time Total: ~5 E 16 pot 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 28

CNGS Physics Run 2007 Total: 7. 9 E 17 pot First brick event 6. 3 E 17 pot 8. 4 E 16 pot 2 E 13 pot/extr. 7. 2 E 16 pot Loss of ventilation control Stop beam Modifications in ventilation control 5 Oct 07 th LHC Radiation Workshop, 6 Stop CNGS: non-standard 29 November 2007 12 Oct 07 19 Oct 07 mode of operation (access) not possible in an INB controlled facility 29 E. Gschwendtner, AB/ATB

On-line Muon Profiles after Optimizations 2 x 1. 4 E 13 pot/extr. Horizontal, pit 1 • Horizontal, pit 2 Pit 1: sensitive to target vs horn alignment • Vertical, pit 1 6 th LHC Radiation Workshop, 29 November 2007 Pit 2: sensitive to beam vs target alignment Vertical, pit 2 E. Gschwendtner, AB/ATB 30

Radiological Issues – < 100 Sv/h outside the horn shielding – < 2 Sv/h in service gallery • Beam off immediately afterwards – 100 m. Sv/h d lle ’! ro veto nt co on is iati ss ce rad Ac th ‘ wi • Beam on: For intervention: dose rate < 2 m. Sv/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! 6 th LHC Radiation Workshop, 29 November 2007 E. Gschwendtner, AB/ATB 31