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Published byViviana Larcher Modified about 1 year ago

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#3224 Sat 17 th November Restored an “AP” set-up with some measurement of Twiss. – The idea was to take some BPM data with a known twiss set-up to see how the bunch-to- bunch position variation correlates with the Twiss. Took BPM data in AR1. Scanned AR1-Q1/4 to close dispersion Scanned AR1-Q1/4 to make isochronous.

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#3224 Twiss AP set up from #3139 See \\Dlfiles03\alice\Analysis\Period 14 data\AP_period13and14\transversemodel\31 39\\Dlfiles03\alice\Analysis\Period 14 data\AP_period13and14\transversemodel\31 39 Repeated the same scans to compare Twiss repeatability. ST1-Q1 scan Q2 = 0.6 A Q3/4 = 0 A ST1-Q2 scan (0-1.4A) with Q1 = 0.40A.

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ST1-Q1 scan Q2 = 0.6 A Q3/4 = 0 A, beamsize measured on ST1-4 Yuri original meas’t on #3139 #3224. Position of minimum looks similar but curve much shallower My analysis of #3139

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ST1-Q2 scan (0-1.4A) with Q1 = 0.40A. beamsize measured on ST1-4 No plot available from Yuri’s file My analysis of #3139 My analysis of #3224

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Twiss Calculation γ.εx (μm) αx(m)βx (m)γ.εy (μm) αy(m)βy(m) #3149 YMS evaluation 8.521.077.43.1-2.3122.3 #3149 My evaluation 9.519.075.7Not done #3224 My Evaluation 6.511.440.7Not done Uses parabolic fit to σ^2 vs k.l Constrain parabola vertical offset to smallest beamsize measurement

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Twiss Conclusions NB: I didn’t go to divisor 20 like Yuri did. But I would expect the result (if any) of this would be to make my beamsizes on #3224 larger due to increased beam loading. However, my beamsizes are smaller. I set up phases “accurately” to match #3224 60pC; BC=-10/+15deg; Lc = crests. Pb=1.2kW. Comparison of the quad scan data suggests optics are not highly repeatable. Two months gap between measurements being compared. Maybe this is too long a gap.

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Model vs Measure #3224 ST1-3 AR2-1 ST2-1 ST2-2 Model/measure agreement not too bad

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Bunch intra-train variation/jitter compared with β function x-plane AR1-BPM-01 AR1-BPM-03 AR1-BPM-04AR1-BPM-06 Plot sqrt(β) (~ beamsize) vs rms x position with the train, for each BPM trace. The β at each BPM comes from model on previous slide. There does seem to be strong correlation, perhaps expected. AR1-BPM-06 AR1-BPM-01 AR1-BPM-03 AR1-BPM-04

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AR1 STUDIES After Twiss evaluation, restore the #3139 “AP” set up and study dispersion and R56 of AR1

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AR1 Dispersion Measured on AR1- BPM-06 Each plot is BPM x position vs beam energy Vary AR1-Q1/4 from 1.9 to 2.4 in 8 steps Dispersion (mm) vs AR1-Q1/4 current

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AR1 R56 measured on AR1-BPM-06 Each plot is BPM relative path length vs beam energy Vary AR1-Q1/4 from 1.9 to 2.4 in 8 steps R56 (mm) vs AR1-Q1/4 current AR1-Q1/4 current

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Summary R16 R56 Isochronous + zero dispersion condition at AR1-Q1/4 = 2.18 A AR1-Q1/4 current

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