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Title: Turn-by-Turn Imaging of the Transverse Beam Profile in PEP-II

Abstract

During injection or instability, the transverse profile of an individual bunch in a storage ring can change significantly in a few turns. However, most synchrotron-light imaging techniques are not designed for this time scale. We have developed a novel diagnostic that enhances the utility of a fast gated camera by adding, inexpensively, some features of a dual-axis streak camera, in order to watch the turn-by-turn evolution of the transverse profile, in both x and y. The beam's elliptical profile is reshaped using cylindrical lenses to form a tall and narrow ellipse--essentially the projection of the full ellipse onto one transverse axis. We do this projection twice, by splitting the beam into two paths at different heights, and rotating the ellipse by 90{sup o} on one path. A rapidly rotating mirror scans these vertical ''pencils'' of light horizontally across the photocathode of the camera, which is gated for 3 ns on every Nth ring turn. A single readout of the camera captures 100 images, looking like a stroboscopic photograph of a moving object. We have observed the capture of injected charge into a bunch and the rapid change of beam size at the onset of a fast instability.

Authors:
; ;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
896414
Report Number(s):
SLAC-PUB-11851
TRN: US0700838
DOE Contract Number:
AC02-76SF00515
Resource Type:
Conference
Resource Relation:
Conference: Presented at 12th Beam Instrumentation Workshop (BIW06), Fermilab, Batavia, Illinois, 1-4 May 2006
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEAM PROFILES; CAMERAS; IMAGES; INSTABILITY; LENSES; MIRRORS; PHOTOCATHODES; STORAGE RINGS; STREAK CAMERAS; Accelerators, Instrumentation,ACCPHY, INST

Citation Formats

Fisher, Alan A., Petree, Mark, and /SLAC. Turn-by-Turn Imaging of the Transverse Beam Profile in PEP-II. United States: N. p., 2006. Web.
Fisher, Alan A., Petree, Mark, & /SLAC. Turn-by-Turn Imaging of the Transverse Beam Profile in PEP-II. United States.
Fisher, Alan A., Petree, Mark, and /SLAC. Mon . "Turn-by-Turn Imaging of the Transverse Beam Profile in PEP-II". United States. doi:. https://www.osti.gov/servlets/purl/896414.
@article{osti_896414,
title = {Turn-by-Turn Imaging of the Transverse Beam Profile in PEP-II},
author = {Fisher, Alan A. and Petree, Mark and /SLAC},
abstractNote = {During injection or instability, the transverse profile of an individual bunch in a storage ring can change significantly in a few turns. However, most synchrotron-light imaging techniques are not designed for this time scale. We have developed a novel diagnostic that enhances the utility of a fast gated camera by adding, inexpensively, some features of a dual-axis streak camera, in order to watch the turn-by-turn evolution of the transverse profile, in both x and y. The beam's elliptical profile is reshaped using cylindrical lenses to form a tall and narrow ellipse--essentially the projection of the full ellipse onto one transverse axis. We do this projection twice, by splitting the beam into two paths at different heights, and rotating the ellipse by 90{sup o} on one path. A rapidly rotating mirror scans these vertical ''pencils'' of light horizontally across the photocathode of the camera, which is gated for 3 ns on every Nth ring turn. A single readout of the camera captures 100 images, looking like a stroboscopic photograph of a moving object. We have observed the capture of injected charge into a bunch and the rapid change of beam size at the onset of a fast instability.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Dec 18 00:00:00 EST 2006},
month = {Mon Dec 18 00:00:00 EST 2006}
}

Conference:
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  • During injection or instability, the transverse profile of an individual bunch in a storage ring can change significantly in a few turns. However, most synchrotron-light imaging techniques are not designed for this time scale. We have developed a novel diagnostic that enhances the utility of a fast gated camera by adding, inexpensively, some features of a dual-axis streak camera, in order to watch the turn-by-turn evolution of the transverse profile, in both x and y. The beam's elliptical profile is reshaped using cylindrical lenses to form a tall and narrow ellipse - essentially the projection of the full ellipse ontomore » one transverse axis. We do this projection twice, by splitting the beam into two paths at different heights, and rotating the ellipse by 90 deg. on one path. A rapidly rotating mirror scans these vertical 'pencils' of light horizontally across the photocathode of the camera, which is gated for 3 ns on every Nth ring turn. A single readout of the camera captures 100 images, looking like a stroboscopic photograph of a moving object. We have observed the capture of injected charge into a bunch and the rapid change of beam size at the onset of a fast instability.« less
  • No abstract prepared.
  • A new apparatus is designed to measure the beam profile turn-by-turn using synchrotron light. The apparatus consists of optical fibers, photo multiplier tubes and digitizers. It is cost efficient and easy to operate. Monte Carlo simulations have shown that the apparatus has an acceptable resolution. The concept has been tested preliminarily at the SLC damping ring, and a full equipment is being set up at CESR to observe coherent beam-beam phenomenon.
  • No abstract prepared.
  • For optics measurement and modeling of the PEP-II electron (HER) and position (LER) storage rings, we have been doing well with MIA [1] which requires analyzing turn-by-turn Beam Position Monitor (BPM) data that are resonantly excited at the horizontal, vertical, and longitudinal tunes. However, in anticipation that certain BPM buttons and even pins in the PEP-II IR region would be missing for the run starting in January 2007, we had been developing a data validation process to reduce the effect due to the reduced BPM data accuracy on PEP-II optics measurement and modeling. Besides the routine process for ranking BPMmore » noise level through data correlation among BPMs with a singular-value decomposition (SVD), we could also check BPM data symplecticity by comparing the invariant ratios. Results from PEP-II measurement will be presented.« less