Collimation for the 2018 heavyion run Work plan

Collimation for the 2018 heavy-ion run

Work plan for collimation • Risk that collimation efficiency becomes bottleneck in 2018 run – important to investigate limitations in advance • Work needed for collimation in standard physics – Determine collimator settings – Simulate collimation cleaning – Check BLM thresholds – do we risk more dumps this year? Mitigations? – Check machine protection aspects – asynch dump • MDs (crystals etc): not discussed here

Collimation • Collimator settings: – Baseline: take over proton run settings. No need to do major changes – Need tighter TCTs in IR 2 – Consider putting the TCTs to 9 sigma (instead of 7. 8 sigma at 25 cm for protons) => if aperture is OK • Simulations of ion cleaning efficiency – To check in advance potential hotspots and understand their origins – To be ready to simulate new configurations of collimation settings if needed – Ongoing: N. Fuster Martinez

BLM margins • BLM thresholds set previously close to estimated quench level. • Not much margin to increase, but could consider optimization of physics time • Analysis of BLM signals and margins to dump in previous runs – Idea: check most critical ratio of BLM signal to dump in all ion physics fills in 2015 -2016 – Outcome: margin to dump operationally and an estimate of how many more dumps we risk if number of bunches is increased, assuming the same lifetime and collimation efficiency – Ongoing: D. Mirarchi – To be discussed also in BLM threshold working group

Protection of aperture • For proton physics, demand MKD-TCT phase advance < 30 deg – for tight TCTs to ensure safety during an asynch. Dump • 2018 ion optics: 48 deg phase advance MKD- IR 2 TCT (S. Fartoukh, HSS meeting 2018) • Is this phase acceptable? Damage during an asynch dump for ions should be much less likely than for protons – – lower bunch charge less dense filling scheme Maybe we don’t need the TCTs so tight To be studied in simulations: N. Fuster Martinez