1. Beam Gas Ionization Monitor (BGI)
Ray VENESS for BE-BI

2. BI group proposal for the BGI
Considering:
Persistent impedance-induced heating of the instrument leading to an increased outgassing rate
Damage to the optical prism, probably due to differential thermal expansion in its support
Limited time and resources available for full simulation and re-design before YETS 17-18
Propose to:
Not re-install the instrument during YETS 17-18
Gain experience from other profile monitors under development for High Lumi (BGV, BGC, BGI for PS) and come back with a proposal for Run III
Implications for LHC operations:
No BGI-based profile monitoring before LS2 – particularly for ions at injection energy
Profile measurement for ions will remain with:
Wire scanners at injection (with usual intensity limit)
BSRT at top energy

3. Beam Induced Florescence measurement in the LHC
Ray Veness

4. Motivation
A beam-gas curtain profile measurement instrument is under development for High-Lumi
2D gas jet target with beam-induced florescence imaged by an ex-vacua optical system
Ideally suited for on-line e-/p+ measurements in the hollow e-lens or e-BBLR
Active international collaboration with a High-Lumi funded deliverable for an LHC-compatible prototype in 2019
Choice of the gas species for the jet is key both for compatibility with the LHC vacuum environment and the measurement integration time
Optimisation of a final instrument for High-Lumi will require experimental data and experience with 7 TeV protons
Fluorescence cross-section for p+ at 7 TeV
Resolution limits with gas jet in the p+ field
Proposal for fluorescence test installation in the LHC during YETS (and later installation of full prototype gas jet curtain monitor in LS2) presented to 37th HL-TCC
The meeting “…expressed the HL-LHC project interest and support for testing this new type of gas monitor.”

5. Proposed experiment
Slide to add from Stefano Mazzoni

6. Proposed installation during YETS 17-18
Re-use the existing BGI gas injection system
Already qualified and extensively used in the LHC
Used in it’s currently installed position underneath the (now removed) BGI
Minor vacuum modifications
Vent one sector
Install one shortened drift vacuum chamber and a ‘cross’ chamber of an existing (slightly modified) design
Connect the gas injection system to the cross and a viewport for imaging the light
Status
ECR – draft circulating for comment
Impedance – (statement to add)
Vacuum – discussions of implementation and gas selection well advanced
Equipment – being procured. Will be available for YETS.

7. Summary
A ‘beam-gas curtain’ instrument based on ‘beam-induced fluorescence’ is under development for High Lumi
Key data for image integration time and resolution can only be gained by measurements at 7 TeV
An experimental programme for this in the LHC is supported by High Lumi
The first step could be installed in the upcoming YETS, taking advantage of the existing infrastructure for the BGI
Discussions with impedance and vacuum are well advanced, with a draft ECR in circulation
BI request the endorsement of the LMC for the YETS installation