Author: Zhukov, A.P.
Paper Title Page
THPB012 High Resolution Emittance Measurements at SNS Front End 870
  • A.P. Zhukov, A.V. Aleksandrov
    ORNL, Oak Ridge, Tennessee, USA
  Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
Spallation Neutron Source (SNS) linac accelerates an H beam from 2.5MeV up to 1GeV. Recently the emittance scanner in the MEBT (2.5 MeV) was upgraded. In addition to the slit - harp measurement we now can use a slit installed on the same actuator as the harp. In combination with a faraday cup located downstream in DTL part of the linac it represents a classical slit-slit emittance measurement device. While a slit – slit scan takes much longer time, it is immune to harp related problems such as wire cross talk and thus looks promising for accurate halo measurements. Time resolution of the new device seems to be sufficient to estimate amount of the beam in the chopper gap (the scanner is downstream of the chopper) and probably measure its emittance. The paper describes initial measurements with new device and some model validation data.
THPB013 Diagnostics Tools for Beam Halo Investigation in SNS Linac 873
  • A.V. Aleksandrov, W. Blokland, Y. Liu, C.D. Long, A.P. Zhukov
    ORNL, Oak Ridge, Tennessee, USA
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
Uncontrolled beam loss is the major concern in operation of a high intensity hadron linac. A low density cloud of particles with large oscillation amplitudes, so called halo, can form around the dense regular beam core. This halo can be direct or indirect cause of beam loss. There is an experimental evidence of halo growing in SNS linac and limiting further reduction of beam loss. A set of tools is being developed for detecting of the halo and investigating its origin and dynamics. The set includes high resolution emittance measurements in the injector, laser based emittance measurements at 1 GeV, and high resolution profile measurements along the linac. We will present our experience with useful measurement techniques and data analysis algorithms as well as current understanding of the halo dynamics in SNS linac.