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.

跃迁辐射（TR）是指当带电粒子穿过光学不均匀区域（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、束流诊断等方面有着广泛的应用。随着材料科学和纳米技术的发展，近年来有一些人工工程材料来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轮廓和纵向平面中的束电荷或电流监测，是加速器操作和优化的基本诊断要求。有几个既定的方法，如二次电子监测器（SEM）网格以及束诱导荧光（BIF）的横向束流剖面测量，然而，随着加速器和束流动力学的快速发展，这些方法的适用性受到质疑的快速辐射硬诊断的背景下，重离子束。它们受到测量轮廓的分辨率、信号产生过程的基本限制以及测量装置对光束轮廓的影响的限制。基于光学跃迁辐射（OTR，即可见光范围内的TR）的光束诊断于1973年被提出，并且在大约50年的时间里，由于具有诸如高光产额、简单的实验装置、可以与不同波长一起工作的可能性等优点而引起了很多关注。过渡辐射的辐射产额和偏振度对入射角和观察角、射束能量和射束轮廓、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继续是许多研究的主题，并且这些发现被利用来改进基于OTR的射束诊断技术。了解跃迁辐射的形成机制、其性质以及灵活塑造其形状的方法，为未来的加速器和对撞机提供了光束诊断仪器以及粒子计数器的新可能性。OTR在重离子束诊断中的应用带来了一系列机遇和挑战。过渡辐射的主要特征之一是在观察平面内的高度偏振。有趣的是，总体产量和极化程度是显着不同的粗糙目标。除了预期的线性极化过渡辐射在观察平面，非极化辐射的一个重要组成部分的报告与粗糙表面和非相对论离子束。理论模型和更深入的理解OTR从粗糙表面看起来是一个很有前途的方式前进到新的光束诊断技术。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共同资助。这项工作将在英国的Cockcroft研究所和德国的GSI进行。