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Title: Beam dumping ghost signals in electric sweep scanners

Abstract

Over the last 20 years many labs started to use Allison scanners to measure low-energy ion beam emittances. We show that large trajectory angles produce ghost signals due to the impact of the beamlet on the electric deflection plates. The strength of the ghost signal is proportional to the amount of beam entering the scanner. Depending on the ions and their velocity, ghost signals can have the opposite polarity as the main beam signals or the same polarity. These ghost signals are easily overlooked because they partly overlap the real signals, they are mostly below the 1% level, and they are often hidden in the noise. However, they cause significant errors in emittance estimates because they are associated with large trajectory angles. The strength of ghost signals, and the associated errors, can be drastically reduced with a simple modification of the deflection plates.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
15011755
Report Number(s):
FERMILAB-CONF-04-514-AD
TRN: US200606%%440
DOE Contract Number:  
AC02-76CH03000
Resource Type:
Conference
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ION BEAMS; MODIFICATIONS; VELOCITY; Experiment-HEP, Instrumentation

Citation Formats

Stockli, M P, /SNS Project, Oak Ridge /Tennessee U., Leitner, M, /LBL, Berkeley, Moehs, D P, /Fermilab, Keller, R, /LBL, Berkeley, Welton, R F, and /SNS Project, Oak Ridge. Beam dumping ghost signals in electric sweep scanners. United States: N. p., 2004. Web.
Stockli, M P, /SNS Project, Oak Ridge /Tennessee U., Leitner, M, /LBL, Berkeley, Moehs, D P, /Fermilab, Keller, R, /LBL, Berkeley, Welton, R F, & /SNS Project, Oak Ridge. Beam dumping ghost signals in electric sweep scanners. United States.
Stockli, M P, /SNS Project, Oak Ridge /Tennessee U., Leitner, M, /LBL, Berkeley, Moehs, D P, /Fermilab, Keller, R, /LBL, Berkeley, Welton, R F, and /SNS Project, Oak Ridge. Wed . "Beam dumping ghost signals in electric sweep scanners". United States. https://www.osti.gov/servlets/purl/15011755.
@article{osti_15011755,
title = {Beam dumping ghost signals in electric sweep scanners},
author = {Stockli, M P and /SNS Project, Oak Ridge /Tennessee U. and Leitner, M and /LBL, Berkeley and Moehs, D P and /Fermilab and Keller, R and /LBL, Berkeley and Welton, R F and /SNS Project, Oak Ridge},
abstractNote = {Over the last 20 years many labs started to use Allison scanners to measure low-energy ion beam emittances. We show that large trajectory angles produce ghost signals due to the impact of the beamlet on the electric deflection plates. The strength of the ghost signal is proportional to the amount of beam entering the scanner. Depending on the ions and their velocity, ghost signals can have the opposite polarity as the main beam signals or the same polarity. These ghost signals are easily overlooked because they partly overlap the real signals, they are mostly below the 1% level, and they are often hidden in the noise. However, they cause significant errors in emittance estimates because they are associated with large trajectory angles. The strength of ghost signals, and the associated errors, can be drastically reduced with a simple modification of the deflection plates.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2004},
month = {12}
}

Conference:
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