Present: Ray, Rhod, Adriana, Christos, Thibaut, Enrico

Gas Jet Developments for HL-LHC (Ray)

• Proposed non-invasive monitoring for parallel e-beam & proton beam profiling 
  • Hollow e-lens
  • Long Range Beam-Beam Compensator based on e-beam
• Collaboration
  • HL-LHC UK - Cockcroft for gas jet development
    • 2 systems (proto/test bench in 2017 & installable device for LS2)
  • GSI
    • Luminescence monitoring
    • Feasibility report & optics design by mid 2017
• 2 Techniques being investigated
  • Gas sheet
  • Gas pencil beam
• Gas Type
  • N2 investigated so far but not preferred for LHC as its pumped by NEG & will saturate NEG over time
  • Looking to noble gases e.g. Neon an alternative
• Simulation Challenges
  • Pressure range spans 11 orders of magnitude (10bar to 10-7mbar)
  • Geometric details range over 4-5 orders of magnitude
    • Nozzles from ~30 μm with transport over ~ 1 m
• Simulation results
  • Addition of baffles before dump to limit backscattered molecules re-entering interaction chamber
  • Good agreement with experimental pressure measurements
• Luminescence results
  • Clear indication of gas sheet observed but integration times very long
    • Main reason is limited current of e-beam (uA)
    • Currently being replaced (mA)

ACTION/Next Steps

• Integration into SC solenoid for hollow e-beam (Ray & Adriana with MME)
• Input on e-beam size & corresponding curtain size (Adriana)
• Plans for future gas luminescence measurements (Ray & Rhodri to clarify with Cockcroft & GSI)

Lumi design for HL : Test Plans in 2017 (Enrico)

• Prototype (quartz & air)
  • Cherenkov
  • Quartz probably only valid for low lumi IRs
  • In 2017 mainly to test high radiation dose dosimeters for RP in IR1
• Geometry of TAXN for HL
  • Space greatly reduced between beampipes
  • Where is the neutral shower a maximum?

ACTIONS:

• Where we can place a monitor?
  • Need to look in detail at TAXN design (Enrico)
• How much of the neutral shower can be intercepted?
  • Look at effect of crossing angle (Enrico / Marcus)
• TAXN design & simulations
  • To be scheduled for presentation in WP13 April/May meeting