Coherent bremsstrahlung in a bent crystal

Abstract

Radiation spectrum from high energy $e^\pm$ in a bent crystal with arbitrary curvature distribution along the longitudinal coordinate is evaluated, based on the stationary phase approximation. For a uniformly bent crystal a closed-form expression for the spectrum is derived. Features such as sharp end of spectrum and volume reflection turnover at beginning of the spectrum are discussed. The coherence length in a bent crystal appears to depend only on the crystal geometry and not on the electron or photon energies, which is essential for interpretation of the results. Estimates of non-dipole radiation and multiple scattering effects are given. The value for the crystal bending angle at which the dipole coherent bremsstrahlung theory holds best appears to be $\sim 10^{-4}\mathrm{rad}$.Comment: 15 pages, 10 figures; published versio

Channeling and Radiation in Periodically Bent Crystals

“…Thus, it is meaningful to discuss a novel source of electromagnetic radiation in hard X and gamma range,-a Crystalline Undulator Laser (CUL) [3,4,6,19,53,74,[76][77][78][79][80] The emitted radiation can be very powerful if the probability density of the particles in the beam is 1. Peak brilliance of the spontaneous CUR was calculated [17,18] for the KEKB positron beam and for the SLAC beam [73] (see also Sect. Peak brilliance of the spontaneous CUR was calculated [17,18] for the KEKB positron beam and for the SLAC beam [73] (see also Sect.…”

“…Peak brilliance of the spontaneous CUR was calculated [17,18] for the KEKB positron beam and for the SLAC beam [73] (see also Sect. The dashed area marks the estimation of the CUL brilliance [74] done with the parameters of the electron beam from the FLASH FEL [7] modulated in the longitudinal direction with the period equal to the wavelength of the emitted radiation (see, e.g., [73]). The dashed area marks the estimation of the CUL brilliance [74] done with the parameters of the electron beam from the FLASH FEL [7] modulated in the longitudinal direction with the period equal to the wavelength of the emitted radiation (see, e.g., [73]).…”

“…These peaks will lead to the non-monotonous structure of the cross section dσ c = dσ c /dω integrated over the emission and scattering angles. 3b and 2a in [216] To conclude this section, we mention that coherent BrS from high energy electrons and positrons in a bent crystal was recently considered in [73], where analytical expressions for the spectrum of emitted radiation were derived. 2.15 (left) which presents the experimental results on the enhancement factor, i.e.…”

Limiting energy loss distributions for multiphoton channeling radiation

“…Dashed green curve, prediction for the singlephoton spectrum of coherent bremsstrahlung in a bent crystal [15].…”

Mean volume reflection angle

“…Another kind of inelastic processes is emission of electromagnetic radiation, which can be intense for ultrarelativistic electrons and positrons passing through crystals [8,11,25]. For radiation at VR, the deviation of the spectrum from the kinematically formed coherent bremsstrahlung in a bent crystal (generated away from the intrinsic VR region) is concentrated in the low-ω region [44]. The infrared limit ω → 0 itself is rather trivial, corresponding to factorization of the radiation and scattering probabilities [44].…”