THE MEASUREMENT OF CHANNELING RADIATION FROM A LINEAR-ACCELERATOR ELECTRON-BEAM AT HIGH CURRENTS

In this paper, we describe the instrumentation used in the production and detection of channeling radiation from a linear-accelerator electron beam at high currents. Channeling-radiation spectra were measured for 30 meV electrons channeled along the (100) and (110) planes of a 15 μm thick silicon crystal. Spectra were taken for photon energies from 10 to 38 keV with a 0.2 keV resolution in 5 minutes. Using an average electron current of 3 μA, over 109 channeling photons/s were incident on the spectrometer, eliminating single-pulse counting as a means of spectral measurement, since collimation to 10-11 sr would have been necessary to avoid pileup. The bremsstrahlung radiation emitted from the channeling target crystal produced a high-energy noise background. A Bragg spectrometer, using a mosaic-spread Bragg crystal, was designed to measure the intense channeling-radiation X-rays in the noisy environment. This spectrometer provides a means to measure intense channeling-radiation spectra from any achievable electron current. © 1990.