The scheme for accurate quantitative treatment of the radiation from a crystalline undulator in presence of the dechanneling and the photon attenuation is presented. The number of emitted photons and the brilliance of electromagnetic radiation generated by ultra-relativistic positrons channeling in a crystalline undulator are calculated for various crystals, positron energies and different bending parameters. It is demonstrated that with the use of high-energy positron beams available at present in modern colliders it is possible to generate the crystalline undulator radiation with energies from hundreds of keV up to tens of MeV region. The brilliance of the undulator radiation within this energy range is comparable to that of conventional light sources of the third generation but for much lower photon energies.
A dielectric laser accelerator, operating at optical frequencies and GHz pulse rate, is expected to produce attosec electron bunches with a moderate beam current at high energy. For relativistic electrons, the attosec bunch has a spatial length of a few nanometers, which is well suited for generating high-brightness superradiance in the VUV, EUV, and x-ray spectra. Our study shows that the brilliance of coherent undulator radiation driven by a short-bunch beam with 1~10 fC bunch charge from a dielectric laser accelerator is comparable to or higher than that of a synchrotron in the 0.1 ~ 3 keV …
The scattering of fast charged particles in a thin crystalline undulator is considered under conditions when all particles of the beam undergo above-barrier motion with respect to the bent crystalline atomic planes. The consideration is based on the analysis of the particles motion in the continuous potential field of the bent crystal atomic planes and on the simulation of the scattering process taking into account the influence of incoherent effects in scattering on the particles motion. The possibility of manifestation of the effect of multiple volume reflection from bent crystalline atomic …
Parameters of the crystalline undulator and its radiation for particular experimental conditions
我们报告了计划用于实验的晶体波荡器的理论和数值分析结果，这些实验是正在进行的PECU项目的一部分[1]。这样的分析的目的是定义的参数（不同于那些预先设定的实验装置）的波荡器，确保最高产量的光子的指定能量。计算了0.6和10 GeV正电子在周期性弯曲Si和Si $_{1-x}$ Ge $_x$晶体中的沟道效应。
From Simulation to Fabrication: Realizing Silicon Crystalline Undulators with Silicon Nitride Stressor Layer Patterning
INFN, Sezione di Ferrara（意大利国家核物理研究所费拉拉分部）；CNR - IMM, Bologna（意大利国家研究委员会材料研究所博洛尼亚分部）；Università degli Studi di Padova（帕多瓦大学）；INFN, Laboratori Nazionali di Legnaro（意大利国家核物理研究所莱尼亚罗国家实验室）；Università degli Studi di Ferrara（费拉拉大学）；MBN Research Center, Frankfurt（MBN研究中心）
We predict peculiar changes in spectral distributions of radiation emitted by ultra-relativistic positrons and electrons in periodically bent crystals with variation of the bending amplitude. It is shown that the changes, being sensitive to the projectile energy, manifest themselves differently for negatively and positively charged projectiles. We demonstrate that the features observed are due to the interplay of different radiation mechanisms occurring in periodically bent crystals. The observations are important for design, practical realization and channeling experiments with periodically b…
The impact of experimental conditions on the observation of channeling and crystalline undulator radiation
Instituto Superior de Tecnologías y Ciencias Aplicadas, University of Havana (InSTEC-UH)（哈瓦那大学应用技术和高等科学研究院）；European Synchrotron Radiation Facility（欧洲同步辐射装置）；MBN Research Center（MBN研究中心）
When a high-energy electrons move in a crystal along one of the crystallographic planes the phenomenon of planar channeling is possible, in which the particles move in channels formed by the continuous potential of crystalline planes. Such particle motion in a crystal is conserved for most particles even for weak bending of crystalline planes of atoms. In [1-3] the process of channeled electrons radiation in such a device was considered. It was shown that the radiation spectrum of particles in the crystal in this case contains maxima associated with the period of oscillation of the channeled p…
Ultrarelativistic charged particles are predicted to emit hard electromagnetic radiation of undulator type while being channeled in a crystal with periodically bent crystallographic planes. The recently proposed crystalline undulator with the bending amplitude smaller than the distance between the bent planes and the bending period shorter than the period of channeling oscillations is far superior to what was proposed previously. In the same time, it is more challenging from the technical point of view because its bending period has to be in the sub-micron range. It is shown that a mixed cryst…
We discuss design and practical realization of novel gamma-ray Crystal-based Light Sources (CLS) that can be constructed through exposure of oriented crystals (linear, bent, periodically bent) to beams of ultrarelativistic charged particles. In an exemplary case study, we estimate brilliance of radiation emitted in a Crystalline Undulator (CU) LS by available positron beams. Intensity of CU radiation in the photon energy range $10^0-10^1$ MeV, which is inaccessible to conventional synchrotrons, undulators and XFELs, greatly exceeds that of laser-Compton scattering LSs and can be higher than pr…
Brilliance of novel gamma-ray Crystal-based Light Sources (CLS) that can be constructed through exposure of oriented crystals to beams of ultra-relativistic charged particles is calculated basing on the atomistic scale numerical modeling of the channeling process. In an exemplary case study, the brilliance of radiation emitted in a diamond-based Crystalline Undulator LS by a 10 GeV positron beam available at present at the SLAC facility is computed. Intesity of CU radiation in the photon energy range 10^0 - 10^1 MeV, which is inaccessible to conventional synchrotrons, undulators and XFELs, gre…
We analyze numerically the radiation and channeling properties of ultrarelativistic electrons and positrons propagating through a periodically bent diamond crystal grown on a straight single-crystal diamond substrate. Such systems can be called hetero-crystals and they are one of the experimentally realized samples for the implementation of crystalline undulators. We state that in such systems the channeling and radiation properties of projectiles are sensitive to the projectile particles energy as well as on the beam propagation direction, i.e. on whether the beam of particles enters the crys…
The generation of X-rays and γ-rays based on synchrotron radiation from free electrons, emitted in magnet arrays such as undulators, forms the basis of much of modern X-ray science. This approach has the drawback of requiring very high energy, up to the multi-GeV-scale, electron beams, to obtain the required photon energy. Due to the limit in accelerating gradients in conventional particle accelerators, reaching high energy typically demands use of instruments exceeding 100's of meters in length. Compact, less costly, monochromatic X-ray sources based on very high field acceleration and very s…
Simple formulas for the probability of radiation of twisted photons by scalar and Dirac particles with quantum recoil taken into account are derived. We show that the quantum recoil does not spoil the selection rule for the forward radiation of twisted photons in the planar undulator: $m+n$ is an even number, where $n$ is the harmonic number and $m$ is the projection of the total angular momentum of the radiated twisted photon. The explicit formulas for the radiation probability of twisted photons produced in the planar wiggler are obtained with account for the quantum recoil. The radiation of…
The feasibility of gamma-ray light sources based on the channeling phenomenon of ultrarelativistic electrons and positrons in oriented crystals that are periodically bent with Small Amplitude and Short Period (SASP) is demonstrated by means of rigorous numerical modelling that accounts for the interaction of a projectile with all atoms of the crystalline environment. Numerical data on the spectral distribution, brilliance, number of photons and power of radiation emitted by 10 GeV electron and positron beams passing through diamond, silicon and germanium crystals are presented and analyzed. Th…
Simulations of electron and positron channelling in a crystalline undulator with a small amplitude and a short period (A Kostyuk, Phys. Rev. Lett. 110 (2013) 115503) were repeated by V G Bezchastnov, A V Korol and A V Solov'yov (J. Phys. B: At. Mol. Opt. Phys. 47 (2014) 195401)for the same parameter set but using another computer code, MBN Explorer, which implements a different model of projectile scattering by crystal atoms. The authors of the latter paper claim that their approach, in contrast to the one of the former paper, allows them to observe short-period undulator oscillations in plots…
We report on the measurements of the spectra of gamma radiation generated by 855 MeV electrons in bent silicon and germanium crystals at MAMI (MAinzer MIkrotron). The crystals were 15 μm thick along the beam direction to ensure high deflection efficiency. Their (111) crystalline planes were bent by means of a piezo-actuated mechanical holder, which allowed to remotely change the crystal curvature. In such a way it was possible to investigate the radiation emitted under planar channeling and volume reflection as a function of the curvature of the crystalline planes. We show that using volume re…
The effect of a finite width of a particle bunch on radiation of twisted photons is studied. The general formulas connecting the radiation probability distribution of twisted photons produced by bunches of identical particles with the radiation probability distribution of twisted photons generated by one particle are obtained for axially symmetric bunches. The bunch is called axially symmetric if it is axially symmetric with respect to the detector axis at some instant of time and all the particles in the bunch move along parallel trajectories. The general sum rules for the probability of radi…
The usage of a Crystalline Undulator (CU) has been identified as a promising solution for generating powerful and monochromatic $γ$-rays. A CU was fabricated at SSL through the grooving method, i.e., by the manufacturing of a series of periodical grooves on the major surfaces of a crystal. The CU was extensively characterized both morphologically via optical interferometry at SSL and structurally via X-ray diffraction at ESRF. Then, it was finally tested for channeling with a 400 GeV/c proton beam at CERN. The experimental results were compared to Monte Carlo simulations. Evidence of planar ch…
Compact ultrafast intense LWFA-driven crystal-based source of $γ$-radiation, positrons and neutrons
INFN Ferrara Division（意大利国家核物理研究所费拉拉分部）；Ulsan National Institute of Science and Technology（蔚山科学技术院）；Gwangju Institute of Science and Technology, Institute for Basic Science（光州科学技术研究院基础科学研究院）；Université Paris-Saclay, CNRS/IN2P3, IJCLab（巴黎萨克雷大学，法国国家科学研究中心/法国国家原子能研究所）
