procedure%20

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Pbar tune removal MD Nov 17, 2002

• procedure schedule
• Schottky spectra with w/o TEL, response to tune
  changes
• scraping (1) intensities, (2) Schottky spectra,
  (3) emittances

XiaoLong Zhang, Vladimir Shiltsev, Frank
Zimmermann, Ops
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• Pbar tune measurements, 1610-1850
• XL had excited A36, then A1, and now A5
• scan p pbar vertical Schottky spectra versus
  noise voltage
• Scan horizontal TEL position, pbar losses up at
  3 mm,
• went up to 5 mm (1st corr at 195, was 27, set
  to 126
• close to pbar), scan TEL timing, select A12
• TEL peak current 150-250 mA (50 noise
  modulation, at 4 V)
• take Schottky data A12 almost gone
• at 1808 take A24, lower noise voltage to 2 V
• take Schottky data w w/o TEL, move QXA up 0.002,
  QYP
• -0.002, QYA down 0.002
• Scraping, 1851-2000
• follow Deans procedure until FBIANG shows zero
  current
• turning off/on TEL has no longer effect on
  Schottky except
• transient
• p chromaticity measurement (/- 10 Hz) Qx13,
  Qy16

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TEL off TEL on
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Pbar spectrum
QHA up by 0.002
proton spectrum
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QVP -0.002 QVA 0.002
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fit inverse parabola to segments to get the tune
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Pbar and proton tunes
QH QV
Pbar 0.5897/-0.0003 0.5741/-0.0002
Protons 0.5822/0.5888 /-0.0003 0.5770/-0.0003
Pbar tune 0.0029 below p in V,
0.0009-0.0075 above p in H
(depending on choice of H p peak)

Step QHA0.002 measured DQH 0.0026 /-0.004
Step QVA-0.002 measured DQV -0.0013 /-0.004
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change of spectra during after Pbar scraping
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Collimator was moved in between 19.5 and 19.8
hours. P chromaticity measured at about 20.0
hours this increased proton bunch length by
0.1-0.2 ns.
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FBIANG shows zero current after scraping, while
SBDAIS is nonzero. Effect of chromaticity
measurement on proton intensity large on
FBIANG, small on TIBEAM and SBDPIS.
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SL centroid positions and beam sizes for 3 bunches
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emittance from scraping
assume 1 step 1 mil
lost fraction exp(-a2/(2s2)), where a is
collimation amplitude
from parabolic fit s 750 mm using D3.2 m and
drms1.15x10-4 get sd373 mm subtracting in
quadrature and using b 200 m, get sb662 mm
normalized emittance 14 mm (18 mm w/o
subtraction)
note the shape does not look Gaussian
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Pbar H emittances before scraping
typical A1 A5 A8 A24
FW 25 52 48 25 40
SL 5 24 22 5? 14
scraping 14?
Pbar V emittances before scraping
typical A1 A5 A8 A24
FW 25 59 58 30 50
SL 12 30 23 12 21
scraping 40??
SL and FW bunch emittances different (factor 2?),
and SL sigmas in logbook again with different
behavior!?!
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Pbar H emittances after 60 scraping
typical A1 A5 A8 A24
FW 15 - 14 15 14
SL 3? - 6 3 8
Pbar V emittances after 60 scraping
typical A1 A5 A8 A24
FW 18 6 21 18 18
SL 9? - 11 9 11
SL and FW bunch emittances still differ by
about a factor of 2
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Pbar H emittances after scraping
typical A1 A5 A8 A24
FW 10 3 - 10 11
SL 7?? - - 7 3
Pbar V emittances after scraping
typical A1 A5 A8 A24
FW 8 7 26 8 9
SL 7?? - - 7 7
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A24 before scraping
A15 after scraping
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Preliminary Conclusions

• we measured pbar tunes at 980 GeV by exciting
• individual pbar bunches with TEL (these
• bunches blew up)
• tunes are 0.003 lower in V and 0.001-0.007
• higher in H, as compared with protons
• p chromaticities 13 and 16
• discrepancy between FBIANG and SBDAIS
• for pbar at low intensity
• differences of factor 2 in pbar beam sizes
• between FW and SL
• beam size from scraping may require more
• sophisticated analysis or refined study

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