Optical transition radiation diagnostics for low energy ion beams

低能离子束的光跃迁辐射诊断

• 批准号: 2816817
• 金额: --
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2816817
• 关键词: Optical; transition; radiation; diagnostics; low

Transition radiation (TR) refers to the emission of electromagnetic radiation when a charged particle moves across an optically inhomogeneous region like the interface between two media with different dielectric properties. Transition radiation have applications in detection of high-energy particles, coherent radiation sources, beam diagnosis etc. With advances in material science and nanotechnol_24ogy, there are some recent studies on shaping the properties of Transition Radiation by artificially engineered materials. Charge distribution diagnostics, typically called beam profiling in transverse plane and beam charge or current monitoring in longitudinal plane, are fundamental diagnostic requirements for accelerator operation and optimization. There are several established methods like secondary electron monitor (SEM) grids as well as beam induced fluorescence (BIF) for transverse beam profile measurement, however, with rapid advances in accelerators and beam dynamics, the suitability of these methods is under question for fast radiation-hard diagnostics in context of heavy ion beams. They are limited by resolution of the measured profiles, fundamental limits on signal generation processes and the effect of measurement apparatus on beam profile. Optical transition radiation (OTR, i.e. TR in visible range) based beam diagnostics was proposed in 1973 and over around 50 years, have gathered a lot of attention due to some advantages like high light yield, simple experimental setup, possibility of working with different wavelengths. Dependence of the radiation yield and the degree of polarization of transition radiation on angle of incidence and angle of observation, beam energy and beam profile, target material and surface characteristics (e.g. roughness), wavelength of emitted radiation etc. continues to be the topic of numerous studies and the findings are exploited to improve OTR based beam diagnostic techniques. Understanding of mechanism of formation of the transition radiation, its properties, and ways to flexibly shape it offers novel possibilities in beam diagnostics instrumentation as well as particle counters for future accelerators and colliders. Application of OTR for heavy ion beam diagnostics comes with its own set of opportunities and challenges. One of the main characteristics of transition radiation is the high degree of polarization in the plane of observation. Interestingly, overall yield and degree of polarization is significantly different for rough targets. In addition to expected linearly polarized transition radiation in the plane of observation, a significant component of unpolarized radiation is reported with rough surface and non-relativistic ion beams. A theoretical model and deeper understanding of OTR from rough surfaces looks a promising way forward to new beam diagnostic technique. This project aims to do that with experiments and simulations to verify this understanding and develop new insights. This project is jointly funded by STFC CDT LIV.INNO and GSI-FAIR, Germany. The work will be carried out at the Cockcroft Institute, U.K and GSI, Germany.

过渡辐射 (TR) 是指当带电粒子穿过光学不均匀区域（例如具有不同介电特性的两种介质之间的界面）时发射的电磁辐射。跃迁辐射在高能粒子探测、相干辐射源、光束诊断等方面具有应用。随着材料科学和纳米技术的进步，最近有一些关于通过人工工程材料塑造跃迁辐射特性的研究。电荷分布诊断，通常称为横向平面中的束流分析和纵向平面中的束流电荷或电流监测，是加速器操作和优化的基本诊断要求。有几种既定的方法，如用于横向束剖面测量的二次电子监视器 (SEM) 网格以及束诱导荧光 (BIF)，然而，随着加速器和束动力学的快速发展，这些方法对于重离子束背景下的快速抗辐射诊断的适用性受到质疑。它们受到测量轮廓的分辨率、信号生成过程的基本限制以及测量设备对光束轮廓的影响的限制。基于光跃迁辐射（OTR，即可见光范围内的 TR）的光束诊断于 1973 年提出，大约 50 年来，由于光产量高、实验装置简单、可以使用不同波长等优点而引起了广泛关注。辐射产量和跃迁辐射的偏振度对入射角和观察角、光束能量和光束轮廓、目标材料和表面特性（例如粗糙度）、发射辐射的波长等的依赖性仍然是众多研究的主题，并且这些发现被用来改进基于 OTR 的光束诊断技术。了解跃迁辐射的形成机制、其特性以及灵活塑造它的方法，为射束诊断仪器以及未来加速器和对撞机的粒子计数器提供了新的可能性。 OTR 在重离子束诊断中的应用有其自身的机遇和挑战。跃迁辐射的主要特征之一是观察平面内的高度偏振。有趣的是，粗目标的总体产率和极化程度显着不同。除了观察平面中预期的线偏振跃迁辐射之外，还报告了粗糙表面和非相对论性离子束的非偏振辐射的重要组成部分。理论模型和对粗糙表面 OTR 的更深入理解看起来是新光束诊断技术的一条有前途的道路。该项目旨在通过实验和模拟来验证这种理解并开发新的见解。该项目由 STFC CDT LIV.INNO 和德国 GSI-FAIR 联合资助。这项工作将在英国考克罗夫特研究所和德国 GSI 进行。