Author/Authors :
Alarcon، نويسنده , , R. and Balascuta، نويسنده , , S. and Benson، نويسنده , , S.V. and Bertozzi، نويسنده , , W. and Boyce، نويسنده , , J.R. and Cowan، نويسنده , , R. and Douglas، نويسنده , , D. and Evtushenko، نويسنده , , P. and Fisher، نويسنده , , P. and Ihloff، نويسنده , , E. and Kalantarians، نويسنده , , N. and Kelleher، نويسنده , , A. and Kossler، نويسنده , , W.J. and Legg، نويسنده , , R. and Long، نويسنده , , E. and Milner، نويسنده , , R.G. and Neil، نويسنده , , G.R. and Ou، نويسنده , , L. and Schmookler، نويسنده , , B. and Tennant، نويسنده , , C. and Tschalنr، نويسنده , , C. and Williams، نويسنده , , G.P. and Zhang، نويسنده , , S.، نويسنده ,
Abstract :
We report measurements of photon and neutron radiation levels observed while transmitting a 0.43 MW electron beam through millimeter-sized apertures and during beam-off, but accelerating gradient RF-on, operation. These measurements were conducted at the Free-Electron Laser (FEL) facility of the Jefferson National Accelerator Laboratory (JLab) using a 100 mev electron beam from an energy-recovery linear accelerator. The beam was directed successively through 6 mm, 4 mm, and 2 mm diameter apertures of length 127 mm in aluminum at a maximum current of 4.3 mA (430 kW beam power). This study was conducted to characterize radiation levels for experiments that need to operate in this environment, such as the proposed DarkLight Experiment. We find that sustained transmission of a 430 kW continuous-wave (CW) beam through a 2 mm aperture is feasible with manageable beam-related backgrounds. We also find that during beam-off, RF-on operation, multipactoring inside the niobium cavities of the accelerator cryomodules is the primary source of ambient radiation when the machine is tuned for 130 mev operation.
Keywords :
Background radiation , Energy recovery linac , Millimeter aperture , Megawatt electron beam , Multipactoring , Beam transmission
