Atomistic Simulations of Ultra-Relativistic Particles Channeling and Radiation in Crystalline Structures

该项目旨在通过晶体波动器（CU）对高能（从~100 keV到GeV范围，相应波长小于0.1埃）单色电磁辐射的新型光源（LS）进行原子级细节的先进计算探索。后者代表定向周期性弯曲晶体（PBC）暴露在超相对论性（高达数百GeV）电子或正电子的光束下。在高能光射体（数十GeV或更高）的极限下，为了保持高辐射损耗率下CUR的稳定性，可以采用一种更复杂的晶体结构-准PBC (qPBC)，其弯曲幅度和周期随穿透距离的变化而变化。该项目的一个研究项目结合了晶体结构（理想和不完美）的理论，计算建模和设计，超相对论粒子动力学与晶体原子的相互作用和辐射阻尼力的作用，以及带电抛射体的光子发射过程。将开发一种先进的多尺度建模算法，使粒子通过宏观尺寸的真实晶体结构传播的有效模拟以及发射辐射的光谱角分布的计算成为可能。结合现代数值算法、先进的计算设备和计算技术，对真实（不完美）晶体中粒子的传播和辐射进行多尺度全原子MD模拟，将使所得结果的预测能力达到与实验相当甚至更高的精度水平。它将把计算建模变成一种工具，可以替代（或成为替代）昂贵的实验室实验，从而降低实验和技术成本。在这个项目过程中获得的理论和计算结果将与现有的实验数据进行比较，并将刺激LSs的进一步技术发展。从长远来看，基于cu的伽马射线LS有可能产生波长小于1埃数量级的相干辐射（FEL类型），即在基于磁波动器的现有LS无法达到的波长范围内。这种LSs将在基础科学中有许多应用，包括核物理和固体物理以及生命科学。

The project aims at the advanced computational exploration, carried out at the atomistic level of details, of a novel Light Source (LS) of high energy (from ~100 keV up to GeV range, the corresponding wavelength less than 0.1 Angstrom) monochromatic electromagnetic radiation by means of a Crystalline Undulator (CU). The latter stands for an oriented periodically bent crystal (PBC) exposed to the beam of ultrarelativistic (up to hundreds of GeV) electrons or positrons. In the limit of highly energetic light projectiles (tens of GeV and higher), to maintain the stability of CUR against high rate of radiative losses, a more complex crystalline structure, - quasi PBC (qPBC), can be used in which bending amplitude and period are varied with the penetration distance. A research programme within the project combines theory, computational modeling and design of the crystalline structures (both ideal and imperfect), of the ultra-relativistic particles dynamics with account for the interaction with crystal atoms and for the action of the radiation damping force, and of the photon emission processes by charged projectiles. An advanced algorithm for multiscale modeling will be developed which enables efficient simulation of particles propagation through realistic crystalline structures of macroscopic sizes as well as calculation of the spectral-angular distribution of the emitted radiation. The multiscale all-atom MD simulations of the particle propagation and radiation in realistic (imperfect) crystals combined with modern numerical algorithms, advanced computational facilities and computing technologies will bring the predictive power of the results obtained up to the accuracy level comparable or even higher than achievable experimentally. It will turn computational modeling into the instrumental tool that could substitute (or become an alternative to) expensive laboratory experiments, and thus reduce the experimental and technological costs. Theoretical and computational results obtained in the course of this project will be compared with available experimental data and will stimulate further technological developments of the LSs. In a longer term, a CU-based gamma-ray LS has a potential to generate coherent radiation (the FEL type) with wavelengths orders of magnitudes less than 1 Angstrom, i.e. within the wavelength range that cannot be reached in existing LSs based on magnetic undulators. Such LSs will have many applications in the basic sciences including nuclear and solid-state physics and the life sciences.