Author: Falowska-Pietrzak, O.E.
Paper Title Page
TUPAB101 Monte Carlo Simulations and Neutron and Gamma Fluence Measurements to Investigate Stray Radiation in the European XFEL Undulator System 1615
 
  • O.E. Falowska-Pietrzak, A. Hedqvist, F. Hellberg
    Stockholm University, Stockholm, Sweden
  • N. Bassler
    DCPT, Aarhus N, Denmark
  • A. Leuschner, D. Nölle
    DESY, Hamburg, Germany
  • F. Wolff-Fabris
    EuXFEL, Schenefeld, Germany
  
  The Eu­ro­pean X-ray Free Elec­tron Laser (XFEL) is an user fa­cil­ity re­search cen­tre gen­er­at­ing ex­tremely bright and ul­tra-short SASE x-ray pulses. The laser flashes are gen­er­ated when elec­trons of GeV en­er­gies pass the un­du­la­tor sys­tems. Even if the dom­i­nat­ing con­tri­bu­tion of the ra­di­a­tion field in the un­du­la­tor is from spon­ta­neous un­du­la­tor ra­di­a­tion, also elec­tron losses can be ob­served, e.g. dur­ing beam steer­ing or due to beam halo, not cap­tured by the up­stream col­li­ma­tion sys­tem. The in­ter­ac­tions of those par­ti­cles with the vac­uum ves­sel wall re­sult in the emis­sion of stray ra­di­a­tion. The LB 6419 de­tec­tor al­lows to mea­sure both the neu­tron and the gamma com­po­nent in the pulsed ra­di­a­tion fields nearby the un­du­la­tors*. Usu­ally, the real-time mea­sure­ments show the dom­i­nance of the gamma sig­nals. How­ever, in case of par­ti­cle loss oc­curs, a neu­tron sig­nal is ob­served. In ad­di­tion, Monte Carlo (MC) sim­u­la­tions con­ducted using the Geant4 code in­di­cate that neu­trons are also pre­sent within the un­du­la­tor’s mag­nets vol­ume. In this work, we pre­sent the LB 6419 mea­sure­ment data and com­pare these to our MC sim­u­la­tions, to char­ac­ter­ize the ra­di­a­tion field nearby the un­du­la­tor seg­ment.
* KLETT, A., LEUSCHNER, A., TESCH, N., A dose meter for pulsed neutron fields, Radiat Meas 45 (2010) 1242-1244 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB101  
About • paper received ※ 19 May 2021       paper accepted ※ 02 June 2021       issue date ※ 18 August 2021  
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