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Title: The Influence of the Off Center of BPM on the Damper System

Abstract

In reference 1, the motion of the beam center and the required parameters of the damper system has been studied. In that study, we assume that the center of the BPM is just on the rerference orbit. Now, the influence of the BPM displacement will be studied.

Authors:
 [1];  [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1119334
Report Number(s):
BNL-101992-2013-IR
DOE Contract Number:
AC02-98CH10886
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS

Citation Formats

Xu, J., and Claus, J. The Influence of the Off Center of BPM on the Damper System. United States: N. p., 1990. Web. doi:10.2172/1119334.
Xu, J., & Claus, J. The Influence of the Off Center of BPM on the Damper System. United States. doi:10.2172/1119334.
Xu, J., and Claus, J. Sat . "The Influence of the Off Center of BPM on the Damper System". United States. doi:10.2172/1119334. https://www.osti.gov/servlets/purl/1119334.
@article{osti_1119334,
title = {The Influence of the Off Center of BPM on the Damper System},
author = {Xu, J. and Claus, J.},
abstractNote = {In reference 1, the motion of the beam center and the required parameters of the damper system has been studied. In that study, we assume that the center of the BPM is just on the rerference orbit. Now, the influence of the BPM displacement will be studied.},
doi = {10.2172/1119334},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Sep 01 00:00:00 EDT 1990},
month = {Sat Sep 01 00:00:00 EDT 1990}
}

Technical Report:

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  • During the accelerator studies period of 12/90 through 1/91 the Accumulator BPM system was investigated in some detail in an effort to improve its reliability and accuracy in making closed orbit measurements. The motivation for this is to try and improve the beam energy resolution for E760. The relativistic {beta} of the {bar p} is given by {beta} = f{sub R}L/c where f{sub R} is the revolution frequency, L is the orbit length ({approx} 474050mm), and c is the speed of light. Hence, the error in {beta} is given by d{beta}/{beta} = df{sub R}/f{sub R} + dL/L. Since df{sub R}/f{submore » R} is {approx} 2 x 10{sup -7}, the main contribution to the error comes from dL. During the E760 run of 5/90 to 9/90 dL was estimated to be {approx} 1mm. It is thought that this can be reduced to {approx} .25mm with proper use of the present BPM system. L is given by L = L{sub 0} + {delta}L where L{sub 0} is the accurately known orbit length of a reference orbit (extracted from an energy scan of the J/{Psi} or {Psi}{prime}), and {delta}L is the difference orbit between the current orbit and the reference orbit. SL is calculated in the 1st approximation by {delta}L = {Sigma}{sub i}C{sub i}{Sigma}{sub j}{Delta}BPM{sub ij} where {Delta}BPM{sub ij} is the horizontal difference orbit at the ith BPM in the jth sector and C{sub i} are constants depending upon the location of the BPM pickup and the strength of the quadrupoles. Table I lists the constants C{sub i}, and Fig. 1 shows a typical difference orbit, {Delta}BPM{sub ij}. These studies were all done with 'reverse protons' and concentrated on closed orbit measurements with the Accumulator horizontal BPMs. The low frequency (H=2) mode of the BPM system is used in all cases, therefore it is required that the beam be bunched with ARF3 at some level. The low frequency RF module in the BPM system had previously been modified to track the H=2 frequency.« less
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