1 / 12

BPMs period 13-14

BPMs period 13-14. General BPM Tasks/Projects. New single bunch BPM electronics on ALICE AR1 + ST2 They had been tested already last year by Alex and Ian Beam based calibration of AR1-BPM-03, see \Dlfiles03aliceAnalysisPeriod 14 dataAP_period13and14BPMAR1BPM1Calibration

vashon
Download Presentation

BPMs period 13-14

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. BPMs period 13-14

  2. General BPM Tasks/Projects • New single bunch BPM electronics on ALICE AR1 + ST2 • They had been tested already last year by Alex and Ian • Beam based calibration of AR1-BPM-03, see \\Dlfiles03\alice\Analysis\Period 14 data\AP_period13and14\BPM\AR1BPM1Calibration • Analysis of AR1-SEXT-01 and QUAD-01,02 misalignment • Beam position, interbunch, intertrain, transients, ripples etc • Variation of bunch position over train on several shifts • Dispersion (1st and 2nd order) measurement throughout ARC-1

  3. Summary of 2011 Tests • See \\dlfiles03\apsv4\Astec\Projects\ALICE\ALICE_Physics_Meeting\2011_09_20 • Some Key Points • Basic BPM resolution/noise is 20-30 um. • Initial train transient seen over 50 bunchers (~5 us) • Ripples seen at different frequencies. • horizontal: • period of (150 to 200) bunches, (80 to 110)kHz, two kinds: a single triangle wave for bunches 100 to 600 and a regular sine-like oscillation for bunches 600 to 1600, where the amplitude is (40 to 60)um; • period about <70 bunches, >230kHz, for bunches 100 to 600, amplitude (20 to 30)um; • vertical: • oscillations for 100 to 600 bunches are similar to that in the horizontal plane; • practically no oscillation of the second kind.

  4. First Shifts #3091-#3123 • Initial shifts #3091, #3121-3123 were used for looking at transients, droop, and ripple. • But the shifts above were problematic for several reasons • Attenuation on buttons set differently to each other • Problems with bunch charge (scope set-up problems) • However, despite problems ripples and transient evident, as in 2011. • Much of the data on these shifts is doubtful because of the problems. A separate ppt for these files … • \\Dlfiles03\alice\Analysis\Period 14 data\AP_period13and14\BPM\bpms3091-3123.pptx • … However, some of this data was valid (attenuation set correctly) and was used for input to IBIC 2012 paper.

  5. #3121 Observations 16 MHz, 100 us (1600 bunch) trains, 30 pC Lattice from a THz-like set-up AR1 probably not closed … (strong-ish AR1Q1/4=2.22 A) Knowledge of beta functions poor/non-existent. mean values subtracted

  6. #3121 Observations • General observations, from a single shot: • bunch to bunch position variation; larger in x than y • various ripples seen on x, y, sum_V • initial “transient”, always on sum_V, sometimes on x, y. • The first observation might be naively expected, since any bunch energy variation would show in x but noty • But since beta functions so poorly understood, not possible to confirm this.

  7. #3121 Analysis. A very rich pictures of ripples, for IBIC 2012! • This data was the basic for the IBIC paper • Fourier-analysed the various frequency components • In x and y • Biggest feature is a ~ 100 kHz oscillation (170 bunches, 10 us) oscillation. Magnet ripple? • Other peaks in the 20-200 kHz range not exactly the same in x and y • Smaller ~300 kHz and 6 MHz signal on both and x and y. Hard to see the 300 kHz on the x,y plots. • In sum_voltage signal • 60-80 kHz signal. Laser pulse power variation? • 300 kHz quite visible on the sum_V. DC-DC converter? • 6 MHz as in x,y • So the biggest effects are the ~100 kHz ripple seen on x,y, and the ~ 60 KHz ripple on charge. I would suggest these are the highest priority to investigate.

  8. AP ‘block’ #3133, 3136, 3141, Week 17th 23rd September • Attenuation set correctly, charge 50-60 pC, 16 MHz • AR1-BPM-01, 03, 04, 05 • Check the x,y sign convention • Varying AR1-Q1-4 to try and generate high dispersion on 1 or more bpms to look for energy transients on trains. • 150-200, 100 kHz bunch oscillation seen very obviously in both x and y, on all BPMs • And similar amplitude in x on BPM-01 as BPM-05, suggesting this is not an energy oscillation • Identical oscillation on x and y on BPM-03. • Able to manipulate amplitude of y amplitude on BPM-05 by ST1-Q2

  9. #3133 • See \\Dlfiles03\alice\Analysis\Period 14 data\AP_period13and14\BPM\3133\3133.ppt • Struck by how regular the oscillation was compared to earlier shifts

  10. #3136 • ~1/2 a shift after FELIS/SNOM problems • Not much intra-train studies on this shift • Trying to measure dispersion, crudely, on AR1-BPM-05 by varying beam energy, and study how AR1-SEXT-01 affects the dispersion here (ideally, it shouldn’t affect dispersion). • Get some decent agreement between theory and measurement • Also can see the T166 component quite easily

  11. #3141 • Some software tweaks for automatic dispersion measurements • Changed beam energy to observe effect on ripple. 100 kHz (and lower freq) enhanced significantly by reducing the energy. • Higher order dispersion T166 observations • Measuring dispersion with single bunch vswhole_train_mean doesn’t make much difference • More detailed effect of sextupole vs. bpm-05 dispersion. • AR1-quad alignment data. • Recording many (1000) trains for train-to-train jitter measurements.

  12. #3168 #3169 6th October 2012. • Strange instability seen on ST2-BPM-03, 1 every 30 refreshes • Alignment data again.

More Related