Ambient beam motion and its excitation by ghost lines in the Tevatron

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Transverse betatron motion of the Tevatron proton beam is measured and analyzed. It is shown that the motion is coherent and excited by external sources of unknown origins. Observations of the time-varying 'ghost lines' in the betatron spectrum are reported. The direct measurement of the rms betatron oscillations amplitude estimates it at about 110 nm at {beta}{sub y} {approx} 900 m. Correspondingly, at the amplitudes at the average beta function location with {beta}{sub y} {approx} 50 m is about 25 nm. Given that such direct measurements with clearly observable betatron peak were not repeatedly reproducible, one can conclude that well ... continued below

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3 pages

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Shiltsev, V. March 1, 2011.

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Transverse betatron motion of the Tevatron proton beam is measured and analyzed. It is shown that the motion is coherent and excited by external sources of unknown origins. Observations of the time-varying 'ghost lines' in the betatron spectrum are reported. The direct measurement of the rms betatron oscillations amplitude estimates it at about 110 nm at {beta}{sub y} {approx} 900 m. Correspondingly, at the amplitudes at the average beta function location with {beta}{sub y} {approx} 50 m is about 25 nm. Given that such direct measurements with clearly observable betatron peak were not repeatedly reproducible, one can conclude that well know 'ghost lines' are the reason for that - as they are come and go without any obvious regularity. Our analysis of these 'ghost lines' shows that (a) besides slow motion across frequencies, they also exhibit oscillatory movements with period varying from 15-20 min to few hours; (b) for the stores analysed, the lines add about factor of 2 to average - over colliding store duration - Schottky power in the betatron bands. The latter allows to estimate that they contribute about half to the previously determined the rms normalized emittance growth rate of some 0.06 {pi} mm mrad/hr. The Tevatron 'ghost lines' look very similar to infamous 'humps' recently observed in the LHC. Those 'humps' are unwanted oscillations seen repeatedly in the LHC beams (mostly in the vertical plane) and also believed to be caused by external excitations.

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3 pages

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  • Presented at 2011 Particle Accelerator Conference (PAC'11), New York, NY, 28 Mar - 1 Apr 2011

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  • Report No.: FERMILAB-CONF-11-070-APC
  • Grant Number: AC02-07CH11359
  • Office of Scientific & Technical Information Report Number: 1012681
  • Archival Resource Key: ark:/67531/metadc840851

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • March 1, 2011

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  • May 19, 2016, 3:16 p.m.

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  • Aug. 30, 2016, 3:45 p.m.

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Shiltsev, V. Ambient beam motion and its excitation by ghost lines in the Tevatron, article, March 1, 2011; Batavia, Illinois. (digital.library.unt.edu/ark:/67531/metadc840851/: accessed August 15, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.