Report on Modifications to the BX12 and BX13 BC1 Dipoles

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Description

Emittance growth seen during the last commissioning run in the bunch compressor optics section, BC1, was blamed on inadequate dipole field quality. The significant linear and nonlinear field non-uniformities generated large horizontal dispersion errors beyond BC1. The linear dispersion after BC1 was corrected using two small 'corrector' quadrupoles placed in BC1 for this purpose, but the remaining nonlinear field caused growth of the normalized horizontal emittance of 40% or more. At best {gamma}{epsilon}{sub x} went from 1.2 {micro}m before BC1 up to 1.7 {micro}m after BC1. The problem was magnified by the larger-than-design energy spread in BC1 due to a ... continued below

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18 pages

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Welch, James; DeBarge, S.; Emma, P.; Fisher, A.; Li, N.; Wu, J. et al. November 23, 2010.

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Description

Emittance growth seen during the last commissioning run in the bunch compressor optics section, BC1, was blamed on inadequate dipole field quality. The significant linear and nonlinear field non-uniformities generated large horizontal dispersion errors beyond BC1. The linear dispersion after BC1 was corrected using two small 'corrector' quadrupoles placed in BC1 for this purpose, but the remaining nonlinear field caused growth of the normalized horizontal emittance of 40% or more. At best {gamma}{epsilon}{sub x} went from 1.2 {micro}m before BC1 up to 1.7 {micro}m after BC1. The problem was magnified by the larger-than-design energy spread in BC1 due to a long initial bunch length. To improve the field quality we decided to modify the two 'inner dipoles', BX12 and BX13, of the four magnet chicane during the four month down time in the Fall of 2007. Only the two inner dipoles were chosen because of the limited time available and the fact that the beam is particularly sensitive to field quality of the inner dipoles due to its very large transverse size when going through them. The modifications were completed in November and included new poles and a new pinning scheme. The outer dipoles were left unchanged.

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18 pages

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  • Report No.: SLAC-R-962
  • Grant Number: AC02-76SF00515
  • DOI: 10.2172/993418 | External Link
  • Office of Scientific & Technical Information Report Number: 993418
  • Archival Resource Key: ark:/67531/metadc1015429

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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.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • November 23, 2010

Added to The UNT Digital Library

  • Oct. 14, 2017, 8:36 a.m.

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  • Nov. 3, 2017, 1:48 p.m.

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Welch, James; DeBarge, S.; Emma, P.; Fisher, A.; Li, N.; Wu, J. et al. Report on Modifications to the BX12 and BX13 BC1 Dipoles, report, November 23, 2010; [California]. (digital.library.unt.edu/ark:/67531/metadc1015429/: accessed January 22, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.