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AWAKE: Preliminary RP simulations

AWAKE: Preliminary RP simulations. Silvia Cipiccia , Eduard Feldbaumer , Helmut Vincke DGS/RP. Outline. Implemented geometry Accident scenario Plasma cell simulations Damage 2 Electronics Conclusions. Implemented Geometry. CNGS 2002: Simple clean geometry. Preliminary AWAKE Geometry.

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AWAKE: Preliminary RP simulations

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  1. AWAKE: Preliminary RP simulations Silvia Cipiccia, Eduard Feldbaumer, Helmut Vincke DGS/RP

  2. Outline • Implemented geometry • Accident scenario • Plasma cell simulations • Damage 2 Electronics • Conclusions

  3. Implemented Geometry CNGS 2002: Simple clean geometry Preliminary AWAKE Geometry 30 cm thick concrete wall 50 cm Ø laser core 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 simple controlled low-occupancy area: 15 Sv/h (to avoid the need for active dosimeter)

  5. Accident scenario e- gallery Effective dose per incident proton (pSv/proton) black dot = entrance of the access gallery big venting tunnel

  6. Accident scenario Accident scenario (from Chiara’s slides): Accident scenario: loosing 1 bunch of nominal beam Safety Code F: Annual dose > 100 Sv Optimization required

  7. Nominal operation requirements Nominal loss intensity equivalent to 15 Sv/h: AWAKE frequency: 0.03 Hz -> 120 bunches/h

  8. Plasma cell simulations • 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 • P+ beam: • Beam size: s =250 mm • Beam lost at the valve (valve fails opening) Rb vapour vacuum Metal shielding Fast valve close Fast valve open

  9. Plasma cell simulations Dose equivalent mSv/bunch (3e11 p+)

  10. Preliminary: damage to electronics • Cumulative damage !!! A Rough Overview Only !!! From M. Brugger presentation for CernFluka user meeting 2008 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

  11. Valve close accident scenario: D2E 1 MeV Neutron equivalent: safe limit 1013 n/cm2 HEH safe limit 107: around the plasma higher Energy Deposited safe limit 2 Gy

  12. Valve open: nominal loss Nominal loss from proton beam expansion in plasma • Proton beam in plasma undergoes SMI->increasing in beam divergence

  13. FLUKA implementation Initial spatial distribution sz 139 mm sx,y 200 mm 0.36 mrad Initial momentum distribution ionized 0.024 mrad Not-ionized

  14. Alexey-FLUKA Comparison • Proton distribution after plasma cell

  15. New Plasma cell: dose equivalent 10 mm steel 6 m long 3 mm steel 6 m long 15 mm steel 6m long

  16. New Plasma cell: HEH fluence per year 10 mm steel 6 m long 3 mm steel 6 m long 15 mm steel 6m long Also for 15 mm radius around plasma cell 1-2 orders of magnitude higher than recommended value

  17. Metal shielding and gas effect 15 mm radius shielding No metal shielding • Also without metal shielding around plasma cell HEH fluence higher than 107 HEH/year • 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

  18. New Plasma cell implementation HEH fluence summary: Still 1 order of magnitude too high Energy deposition comparison:

  19. Proposed solution • Larger plasma cell with off set valve Broad electron beam Proton beam axis ENTRANCE EXIT 2 cm 5.7 cm 3 mm Electron and proton beams have same axis Metal shielding 3 cm • More room at the entrance for large electron beam • Exit is not a problem: electrons and protons on the same axis

  20. Conclusion • The presence of the metal shielding for the electron beam creates hard environment for electronics • The expected values for 1 MeV equivalent neutron, energy deposition and HEH fluence depend on the geometry of the shielding • The minimum level of HEH fluence is set by the interaction of the proton beam with the gas: still 1-2 orders of magnitude higher than recommended -> shielding may be required for diagnostic around plasma cell • Which material to use for the plasma cell wall? More details needed • Preliminary results only: waiting for technical design to implement final geometry

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