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12th HiLumi WP2 Task Leader Meeting
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Europe/Zurich
6/R-018 (CERN)
Minutes of the 12th WP2 Task Leader Meeting held on 08/07/2013
Present: G. Arduini, R. De Maria, M. Giovannozzi, T. Pieloni, A. Valishev, A. Wolski
Minutes of the last meeting and follow-up of actions
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A review of the energy deposition data including the matching section and of the collimation protection will be organized tentatively for 13/08.
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Ezio has provided the error table for the worst case scenario (5 T and 105 mm aperture has been given) a factor 4 improvement is expected for 3.5 T and 95 mm). Massimo has passed the information to the SLAC colleagues for dynamic aperture calculations for the worst case scenario and for errors smaller by a factor 4.
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Concerning the ground motion stability of the triplets and D1 Oliver suggested reviewing the existing measurements and installing accelerometers during LS1 to get additional measurements of the amplitude and frequency spectrum of the triplets. Action: Gianluigi to contact Dominique Missiaen or Helene Mainaud Durand for that. The impact on orbit stability at the IP should be then evaluated and possible correction techniques investigated. Oliver reminded that the correction of the orbit at the IP by feedback was not easy in RHIC.
General information (Gianluigi)
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The 3rd Joint Hi-Lumi LHC-LARP Annual Meeting will take place in Daresbury from 11 to 14 November. A preliminary skeleton programme has been circulated by Lucio. Gianluigi encouraged the Task Leaders for proposals for possible topics to be presented at the meeting during the parallel sessions. Gianluigi will discuss with Andy, Ezio and Erk possible subjects upon his return from holidays.
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Oliver is organizing the session on parameters and layout (possible subjects include: IR1/5 layout update, powering and cooling considerations, RLIUP meeting outcome and update on LIU, Beam-Beam Long Range Compensation, Halo control, crab cavities space requirements and remote handling).
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Oliver suggested as a possible subject the outcome of the review on the transverse instabilities and intensity limitations that will be held on 25-26 September 2013.
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Giorgio Apollinari has been selected as the next Director of the US LHC Accelerator Research Program (LARP) starting from 1/7/2013
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The CERN Medium Term Plan including the first part of HL-LHC Project (Performance Improvement Consolidation) has been approved by Council
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Gianluigi will be on holidays form tomorrow 9/7 until 23/7 included. Next meeting will take place on Thursday 25/7 at 16:30 and it will be dedicated to the analysis made by S. Fartoukh concerning the pile-up density and possible mitigation measures. Possible scenarios will be presented and implications discussed.
Status of Weak Strong Simulations (Sasha)
Simulation tools are now well advanced both in SixTrack and Lifetrack. Preliminary simulations of the dynamic aperture have been performed for different optics configurations and for the 4D and 6D lenses. A significant reduction of the dynamic aperture is observed for *=10 cm, for the 6D lens when multipole errors are included. The reason is not fully understood. Sasha noted that the analysis of the Frequency Map Analysis plots could provide useful information on the origin of that.
On a question of Tatiana Gianluigi and Oliver replied that in the nominal scheme no separation should be assumed in LHCb while full separation should be assumed for ALICE.
Gianluigi noted that before starting a detailed campaign of simulations benchmarking of the Lifetrack and Sixtrack simulations should be performed with nominal beam parameters (see PLC table for 25 ns at https://espace.cern.ch/HiLumi/PLC/_layouts/xlviewer.aspx?id=/HiLumi/PLC/SiteAssets/Parameter%20Table.xlsx&Source=https%3A%2F%2Fespace%2Ecern%2Ech%2FHiLumi%2FPLC%2FSiteAssets%2FForms%2FAllItems%2Easpx&DefaultItemOpen=1 ):
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Without beam-beam for a given error-table to be defined by Massimo (the list of error tables is provided in the Task 2.3 webpage: https://espace.cern.ch/HiLumi/WP2/task3/SitePages/Home.aspx )
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With beam-beam (4D and 5 slices as for nominal LHC) with full crabbing, no separation and *=15 cm in IP1 and 5, with no crabbing, no separation and *=3 m in IP8, with no crabbing, full separation and *=10 m in IP2. Error Table as above.
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With beam-beam (6D) with full crabbing, no separation and *=15 cm in IP1 and 5, with no crabbing, no separation and *=3 m in IP8, with no crabbing, full separation and *=10 m in IP2. Error Table as above.
Sasha said that this should be possible in one month. Action: Sasha, Tatiana.
Gianluigi added that Daniel Schulte might join the HL-LHC beam-beam team for the continuation of the studies of the long range beam-beam compensation.
Gianluigi and Tatiana stressed that it would be important to benchmark simulations with experimental data from the 2012 LHC run. Ji Qiang would be interested to conduct strong-strong simulations to reproduce LHC data. Sasha will verify whether support from LARP exists for those studies. Action: Sasha.
Aperture in triplet - matching section (Riccardo)
The poorer field quality at the D2 might imply a reduction of the aperture that might result in a reduction of the aperture in the TAN-D2-Q4 area so that these elements might not be in the shadow of the triplet anymore.
The collimator settings have strong implications in terms of impedance therefore the settings used for the computation of the protection should be explicated. Two possible settings have been transmitted so far to the impedance team. Action: Stefano to send the list of 7 TeV settings for the collimators to Riccardo and Gianluigi for reference in the WP2 web page.
The protection in beam sigmas for the two considered collimator settings depends on the tolerances used.
The tolerances used for the LHC collimation design are rather conservative and should be reviewed in light of the 2012 experience. Furthermore according to the tolerances considered different aperture bottlenecks might stick out. Action: Massimo and Stefano to launch the critical review of the tolerances in collaboration with OP.
Reported by: Gianluigi and Riccardo
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