Vacuum requirements for RHIC

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In this note the lifetime due to inelastic scattering of beam and residual gas ions is calculated in units of pressure (Torr). In addition, the transverse emittance growth due to elastic scattering is expressed in units of pressure. The definition of inelastic scattering includes both capture of an electron from a residual gas ion and central nuclear collisions between beam ion and gas atom. Emittance growth via elastic scattering is a simple consequence of multiple Coulomb scattering. Is is important to note that in an accelerator only the density of residual gas atoms is relevant to the machine operation. The ... continued below

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Pages: (11 p)

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Rhoades-Brown, M.J. & Harrison, M. December 1, 1991.

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Description

In this note the lifetime due to inelastic scattering of beam and residual gas ions is calculated in units of pressure (Torr). In addition, the transverse emittance growth due to elastic scattering is expressed in units of pressure. The definition of inelastic scattering includes both capture of an electron from a residual gas ion and central nuclear collisions between beam ion and gas atom. Emittance growth via elastic scattering is a simple consequence of multiple Coulomb scattering. Is is important to note that in an accelerator only the density of residual gas atoms is relevant to the machine operation. The measure of this density is the vacuum gauge, where this gauge is calibrated in pressure units at some known temperature T{sub G}. The vacuum unit or pressure is of course temperature dependent, and thus when quoting vacuum requirements for RHIC it is vital to state the temperature at which the pressure is computed. It might be necessary to scale any computed gas density to the pressure appropriate for the measurement with the vacuum gauge. Typically, the vacuum gauge operates at room temperature {approximately}300{degree}K. An explanation on how to rescale pressure as a function of temperature is given in the text. This note assumes the residual gas density in the so-called warm section (300{degree}K) of RHIC to be composed of 90% H{sub 2}, 5% CH{sub 4} and 5% CO. The gas in the cold section (5{degree}K) is assumed to be 100% He. The beam ions are taken to be {sup 197}Au{sup 79+}.

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Pages: (11 p)

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  • Other: DE92007187
  • Report No.: BNL-47070
  • Report No.: AD/RHIC--106
  • Grant Number: AC02-76CH00016
  • DOI: 10.2172/5918014 | External Link
  • Office of Scientific & Technical Information Report Number: 5918014
  • Archival Resource Key: ark:/67531/metadc1097760

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  • December 1, 1991

Added to The UNT Digital Library

  • Feb. 18, 2018, 3:59 p.m.

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  • April 23, 2018, 12:52 p.m.

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Rhoades-Brown, M.J. & Harrison, M. Vacuum requirements for RHIC, report, December 1, 1991; Upton, New York. (digital.library.unt.edu/ark:/67531/metadc1097760/: accessed October 18, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.