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Title: Calibration And Simulation of the LCLS Undulator Beam Loss Monitors Using APS Accelerators

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1278188
Report Number(s):
SLAC-PUB-16678
DOE Contract Number:
AC02-76SF00515
Resource Type:
Conference
Resource Relation:
Journal Name: Conf.Proc.C110328:618-620,2011; Conference: Particle Accelerator, 24th Conference (PAC'11) 28 Mar - 1 Apr 2011, New York, USA
Country of Publication:
United States
Language:
English
Subject:
Accelerators,ACCPHY

Citation Formats

Dooling, J.C., Berg, W., Brill, A., Erwin, L., Yang, B.-X., /Argonne, Fisher, A.S., Nuhn, H.-D., Santana-Leitner, M., and /SLAC. Calibration And Simulation of the LCLS Undulator Beam Loss Monitors Using APS Accelerators. United States: N. p., 2016. Web. doi:10.2172/1278188.
Dooling, J.C., Berg, W., Brill, A., Erwin, L., Yang, B.-X., /Argonne, Fisher, A.S., Nuhn, H.-D., Santana-Leitner, M., & /SLAC. Calibration And Simulation of the LCLS Undulator Beam Loss Monitors Using APS Accelerators. United States. doi:10.2172/1278188.
Dooling, J.C., Berg, W., Brill, A., Erwin, L., Yang, B.-X., /Argonne, Fisher, A.S., Nuhn, H.-D., Santana-Leitner, M., and /SLAC. 2016. "Calibration And Simulation of the LCLS Undulator Beam Loss Monitors Using APS Accelerators". United States. doi:10.2172/1278188. https://www.osti.gov/servlets/purl/1278188.
@article{osti_1278188,
title = {Calibration And Simulation of the LCLS Undulator Beam Loss Monitors Using APS Accelerators},
author = {Dooling, J.C. and Berg, W. and Brill, A. and Erwin, L. and Yang, B.-X. and /Argonne and Fisher, A.S. and Nuhn, H.-D. and Santana-Leitner, M. and /SLAC},
abstractNote = {},
doi = {10.2172/1278188},
journal = {Conf.Proc.C110328:618-620,2011},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 7
}

Conference:
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  • The LCLS Undulator Beam Loss Monitor System is required to detect any loss radiation seen by the FEL undulators. The undulator segments consist of permanent magnets which are very sensitive to radiation damage. The operational goal is to keep demagnetization below 0.01% over the life of the LCLS. The BLM system is designed to help achieve this goal by detecting any loss radiation and indicating a fault condition if the radiation level exceeds a certain threshold. Upon reception of this fault signal, the LCLS Machine Protection System takes appropriate action by either halting or rate limiting the beam. The BLMmore » detector consists of a PMT coupled to a Cherenkov radiator located near the upstream end of each undulator segment. There are 33 BLMs in the system, one per segment. The detectors are read out by a dedicated system that is integrated directly into the LCLS MPS. The BLM readout system provides monitoring of radiation levels, computation of integrated doses, detection of radiation excursions beyond set thresholds, fault reporting and control of BLM system functions. This paper describes the design, construction and operational performance of the BLM readout system.« less
  • We report on the calibration and use of fast fiber-optic (FO) beam loss monitors (BLMs) in the Advanced Photon Source storage ring (SR). A superconducting undulator prototype (SCU0) has been operating in SR Sector 6 (“ID6”) since the beginning of CY2013, and another undulator SCU1 (a 1.1-m length undulator that is three times the length of SCU0) is scheduled for installation in Sector 1 (“ID1”) in 2015. The SCU0 main coil often quenches during beam dumps. MARS simulations have shown that relatively small beam loss (<1 nC) can lead to temperature excursions sufficient to cause quenchingwhen the SCU0windings are nearmore » critical current. To characterize local beam losses, high-purity fused-silica FO cables were installed in ID6 on the SCU0 chamber transitions and in ID1 where SCU1 will be installed. These BLMs aid in the search for operating modes that protect the SCU structures from beam-loss-induced quenching. In this paper, we describe the BLM calibration process that included deliberate beam dumps at locations of BLMs. We also compare beam dump events where SCU0 did and did not quench.« less
  • No abstract prepared.
  • To maintain gain in the 100 m long linac-driven Linac Coherent Light Source (LCLS) FEL undulator, the electron and photon beams must propagate colinearly to within -5 {micro}m rms over distances comparable to the 11.7 m FEL gain length in the 6 mm diameter undulator vacuum chamber. The authors have considered a variety of intercepting and non-intercepting position monitor technologies to establish and maintain this beam alignment. They present a summary discussion of the applicability and estimated performance of monitors detecting synchrotron radiation, transition and diffraction radiation, fluorescence, photoemission or bremsstrahlung from thin wires, Compton scattering from laser beams, andmore » image currents from the electron beam. They conclude that: (1) non-intercepting RF cavity electron BPMs, together with a beam based alignment system, the best suited for this application; and (2) insertable intercepting wire monitors are valuable for rough alignment, for beam size measurements, and for simultaneous measurement of electron and photon beam position by detecting bremsstrahlung from electrons and diffracted x-rays from the photo beam.« less