Spectral brilliance of channeling radiation at the ASTA photoinjector

Abstract

We study channeling radiation from electron beams with energies under 100 MeV. We introduce a phenomenological model of dechanneling, correct non-radiative transition rates from thermal scattering, and discuss in detail the population dynamics in low order bound states. These are used to revisit the X-ray properties measured at the ELBE facility in Forschungszentrum Dresden-Rosenstock (FZDR), extract parameters for dechanneling states, and obtain satisfactory agreement with measured photon yields. The importance of rechanneling phenomena in thick crystals is emphasized. The model is then used to calculate the expected X-ray energies, linewidths and brilliance for forthcoming channeling radiation experiments at Fermilab's ASTA photoinjector. * tsen@fnal.gov

Optics and bremsstrahlung estimates for channeling radiation experiments at FAST

“…The crystal is oriented so that the electron beam propagates parallel to the (110) plane of the crystal. The expected spectra of CR at FAST were reported earlier [6,8]. In this report, we present detailed calculations of the beam optics, background to CR from bremsstrahlung, electron beam distributions after the diamond crystal with and without channeling, and the X-ray detector system for the CR experiments.…”

“…However, the beam divergence for a channeled electron has been shown to be about 0.2 -0.6 times smaller than that obtained from Eq. (6-1) [8]. Using recently added modules in Geant4 [16,9], we estimated the scattering angles and energy spreads of the electron beam passing through the crystal under both channeling and non-channeling conditions.…”

“…. The CR spectrum calculations reported here were done using a Mathematica notebook which was significantly corrected and modified from the published version [11], this modified version was used to successfully compare simulations with experimental results from a previous channeling experiment [8]. The CR…”

Experience with crystals at Fermilab accelerators

“…Recently constructed Fermilab Accelerators Science and Technology (FAST) facility 12 hosted series of studies aimed to produce high brightness X-rays using a low-emittance 50 MeV electron beam, and to demonstrate that CR can be used as a compact high-brightness X-rays source 13,14 . The FAST injector 15 (see main parameters in Table 1) which consists of a CsTe photocathode located in a 1+1/2-cell RF gun followed by two L-band (1.3 GHz) superconducting accelerating structures can generate a low emittance electron beam.…”

Compact and intense parametric x-ray radiation source based on a linear accelerator with cryogenic accelerating and decelerating copper structures

“…The energy spread of PXR is approximately 1% [7]. It is much narrower than what is available from other x-ray generation methods with a crystal and charged particles, for example, channeling radiation [8][9][10] and transition radiation [11]. The yield of PXR, which depends on a Fourier expansion of electric susceptibility, is at most 10 −5 -10 −6 photons=electron [12][13][14].…”