Author: Evtushenko, P.E.
Paper Title Page
Progress Towards Transverse Beam Profile Measurements with Dynamic Range of 10+6  
  • P.E. Evtushenko, J.E. McKisson, D.W. Sexton
    JLab, Newport News, Virginia, USA
  Funding: Work supported by US DOE office of Basic Energy Sciences under the early career program; DOE award number FWP#JLAB-BES11-05
Future high average brightness FELs, operated with CW electron beams, and other high average current LINACs will require extremely good control of beam halo. Based on JLab FEL experience of operating IR FEL with average beam current of 9 mA, it was suggested that, beam diagnostics with large dynamic range (LDR) of 10+6 or higher, are necessary to improve understanding of beam halo formation, its sources and evolution. In this contribution we describe status of two LDR transverse beam profile diagnostics, which are under development at Jefferson Lab. First is beam imaging, where diffraction usually causes a strong limitation of the dynamic range. It was suggested that amplitude apodization of the imaging optics will allows to achieve much higher dynamic range. We present results of such apodized optics evaluation on an optical test bench. Wire-scanners are also capable of LDR measurements. We argue that the best dynamic range (DR) will be given by PMT based detection scheme, when a combination of counting and analog mode for PMT signal processing is used. We present designs of several PMT current measurements techniques with DR larger than 10+6 and results of their laboratory tests.