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MD and ion optics correction status and Xsuite for optics design
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MD and ion optics correction status and Xsuite for...
Meeting on machine development and ion optics correction status and Xsuite for optics design
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Rogelio says the proposed LHC schedule foresees to run in 2026 until June, start HL-LHC in June 2030, drop LS5 and run until 2041. For next year, it is proposed to run with nominal triplet polarity in IR1 and opposite in IR5, swap crossing angle planes in IR1, 5 and to use flat optics. MD4 is scheduled for this weekend including HL-LHC optics studies early on Sunday. Tobias reports on progress with the AC-dipole hardware, that can be expected to be available for optics studies and that there is now a spare amplifier.
Using Xsuite for optics design, Riccardo De Maria, slides
Riccardo illustrates what can now be done using Xsuite, developed with Giovanni Iadarola and colleagues. Using a Jupyter notebook he demonstrates that Xsuite can be used to conveniently perform optics design, including twiss parameter calculation and matching with possibilities to interactively change parameters and display results. For the LHC, detailed modeling is available as lhcoptics package, that can be installed using pip install lhcoptics for Python. The model for the LHC includes strengths, parameters, knobs, sections, aperture and tools to extract detailed hardware information like transfer functions, current limits and circuit parameters that can be used to constrain matching. About 50% of the codes are completed, already sufficient to put a new optics cycle into the LHC, and the goal is to add essential missing features by the end of the year. Extend this to HL-LHC and include error handling is also planned.
Felix is interested to use this for LEIR and is willing to help with the porting.
Extension to other machines with a unification of methods is planned with Giovanni during LS3.
Stephane asks if the extraction of hardware limitations for the LHC can used to match a squeeze including an optimization of the ramp rate. Riccardo replies that current and voltage information can be extracted and used to estimate the ramp rate. Tobias says not everything is in LSA and that some information like getting under-voltage errors is only seen when actually playing the settings in the machine.
Rogelio asks about Wise tables stored on afs. Riccardo says loading them should not be difficult, but requires some extra code to be written. The dipolar b2 errors along with their MQT corrections have revealed very relevant for optics with high ATS factors. This point should be included in the optics design phase.
HL MD optics corrections, Yannis Angelis, slides
Yannis presents his analysis and correction strategy for the high luminosity LHC optics recorded in a recent machine development session. Arcs 45, 81 need more correction. He re-created the phase part of the Segment by Segment (SbS) analysis in Xsuite and uses and optimizes orbit bumps in sextupoles to correct and minimize phase errors. He shows the expected results for beam 1. Model creation is done using the Beta-Beat.src scripts using various sets of orbit correctors to generate and match bumps and evaluate phases. The best and simplest options have similar bumps on the right side of the problematic arcs.
Ion optics corrections, Tobias Persson, slides
Tobias discusses optics corrections relevant for the upcoming heavy ion (HI) run. The global beta-beat and dispersion look fine throughout the cycle and the optics is as expected in IP1,5. More significant deviations with a waist shift are observed in the beta* measurement with K-modulation for IP2 and no global correction was found to correct IP2 beam 2 conserving the good overall agreement. Tobias proposes a new set of local IP2 triplet corrections for implementation and a re-measurement in the HI commissioning,
Rogelio proposes to also check the single pass dispersion.
Tobias said it is also planned to re-measure soon the optics for the proton-proton reference run.
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