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Preliminary RP simulations concerning proton beam losses in AWAKE

Preliminary RP simulations concerning proton beam losses in AWAKE. Silvia Cipiccia 1,2 , Eduard Feldbaumer 2 , Helmut Vincke 2 1 University of Strathclyde 2 CERN DGS/RP. Outline. Implemented geometry Accident scenario Metal shielding effect Prompt dose Damage 2 Electronics

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Preliminary RP simulations concerning proton beam losses in AWAKE

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  1. Preliminary RP simulations concerning proton beam losses in AWAKE Silvia Cipiccia1,2, Eduard Feldbaumer2, Helmut Vincke2 1 University of Strathclyde 2 CERN DGS/RP

  2. Outline • Implemented geometry • Accident scenario • Metal shielding effect • Prompt dose • Damage 2 Electronics • Air Activation • Conclusions

  3. Implemented Geometry CNGS 2002: Simple clean geometry Preliminary AWAKE Geometry 30 cm thick concrete wall e-gun room Access gallery p+ beam 50 cm Ø laser core CNGS target 80 cm thick concrete wall

  4. Accident Scenario • Beam Parameters: • Copper target: Ø = 10 cm, l = 50 cm • Beam position: 10 cm before copper • 2 different scenarios (worst cases): • Full beam loss in front of big venting gallery • Full beam loss in front new electron gallery • Dose conversion coefficient: EWT74 worst case scenario Dose limit for low-occupancy supervised radiation area: 15 Sv/h (to avoid future need for active dosimeter)

  5. AccidentScenario Effective dose per incident proton (pSv/proton) e- gallery big venting tunnel Accident scenario loosing 1 bunch of nominal beam (from Chiara): Safety Code F: Annual dose > 100 Sv Optimization required

  6. Plasma cell • P+ beam: • Beam size: s =250 mm • Beam lost at the valve (valve fails opening) • Plasma Channel • 5 m long • 4 cm Ø • Rb vapor (1015 cm-3 ->1.4x10-7 g/cm3) • Fast Valve: 5 mm thick, 4 cm Ø, material steel AISI304 • Metal shielding: cylinder • inner diameter 30 mm, • thickness 2mm, • material steel AISI304 • length 6m Rb vapour vacuum Fast valve close Fast valve open Metal shielding

  7. Proton beam evolution From Alexey simulations: • Proton beam in plasma undergoes SMI->increasing in beam divergence

  8. Proton beam evolution Initial distributions sz 139 mm sx,y 200 mm 0.36 mrad ionized Not-ionized 0.024 mrad

  9. Alexey-FLUKA Comparison Proton distribution after plasma cell

  10. Valve close accident scenario Dose equivalent mSv/bunch (3e11 p+)

  11. Preliminary: damage to electronics • Cumulative damage !!! A Rough Overview Only !!! commercial COTS hardened electronics accelerators Semiconductors Polymers Ceramics Metals and alloys • Stochastic damage • From M. Brugger ‘Radiation Damage to electronics at the LHC’, IPAC2012: • Commercial equipment: ~107 HEH/cm2/year From M. Brugger presentation for CernFluka user meeting 2008

  12. Closed valve accident scenario: D2E 1 MeV Neutron equivalent: safe limit 1013 n/cm2 HEH safe limit 107 cm-2: exceeded in vicinity of plasma Energy Deposited safe limit 102Gy

  13. Metal shielding effect: Dose equivalent [mSv/bunch] 10 mm steel 6 m long 3 mm steel 6 m long 15 mm steel 6m long

  14. Metal shielding effect: HEH fluence per year safe limit 107cm-2 10 mm steel 6 m long 3 mm steel 6 m long 15 mm steel 6m long For 15 mm radius around plasma cell still 1-2 orders of magnitude higher than recommended value

  15. Metal shieldingeffect: 1 MeV n-eqper year safe limit 1013 n/cm2 3 mm steel 6 m long 10 mm steel 6 m long 15 mm steel 6m long

  16. Metal shielding and gas effect:HEH fluence No metal shielding 15 mm radius shielding • Without metal shielding around plasma cell HEH fluence still higher than 107 cm-2 • Looking at beam profile: halo due to the interaction of proton beam with gas: • Gas interaction length for 400 GeV p+: 109 cm -> in 10 m 3x105 p+ per beam interact with the gas and broaden the beam Scattered particles

  17. Metal shielding summary HEH fluence summary: Still 1 order of magnitude too high Energy deposition comparison: 1 MeV neutron equivalent From preliminary studies level below damage limit

  18. Air Activation Air Activation studies in the CNGS target chamber during AWAKE operation CNGS target chamber Target Horn Reflector Beam He Tube1 He Tube2 Decay Tube • SIMULATION PARAMETERS: • Proton beam starting point: Beginning of Plasma cell 33.01m upstream from CNGS target • Irradiation time 1h • Air exchange rate: 16000 m3/h (CNGS flush mode)

  19. Dose rate AWAKE-CNGS Three scenarios: Implemented geometry CNGS target Collimator Collimator CNGS target Target No Target

  20. Air Activation Dose rate evolution collimator Ultimate beam 1h: 3.5E11 p/bunch, 0.14 Hz Air volume: 2492 m3 Air exchange rate: 16000 m3/h 40 min

  21. Air Activation Dose rate evolution target Ultimate beam 1h: 3.5E11 p/bunch, 0.14 Hz Air volume: 2493 m3 Air exchange rate: 16000 m3/h 30 min 4.5h

  22. Air Activation Dose rate evolution no target Ultimate beam 1h: 3.5E11 p/bunch, 0.14 Hz Air volume: 2493 m3 Air exchange rate: 16000 m3/h 20 min 1.5h

  23. Conclusion • PROMT DOSE AND D2E SIMULATIONS • The presence of the metal shielding for the electron beam creates hard environment for electronics. The level of radiation depends on the geometry of the shielding • The minimum level of HEH fluence due to gas effect: 1-2 orders of magnitude higher than recommended -> shielding may be required • Which material to use for the plasma cell wall? More details needed • Preliminary results only: waiting for technical design to implement final geometry • AIR ACTIVATION • Air inside CNGS target chamber considered radioactive after 1h of nominal AWAKE beam operation • Airborne radioactivity level inside CNGS target chamber • Limited stay area • Ok, no access required during AWAKE operation • Radioactive Air release through access gallery: no access during proton operation • Ventilation and access requirements: still under discussion • Collimator should be removed, CNGS target removal not necessary

  24. Thanks for your attention!

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