Time profile monitor for femtosecond-long electron bunches

自由电子激光器（下一代光源）和高梯度粒子加速器领域的快速发展决定了对能够精确测量飞秒单个和调制电子束的纵向轮廓和特征的纵向聚束轮廓、单次激发、检测器的需求。加速器和自由电子激光器性能的监测和理解需要时间剖面，这决定了其产生相干X射线的能力以及在粒子对撞机和医学用途上的适用性。这是特别重要的新型加速器的基础上唤醒场相互作用的初始条件和环境对电子束参数，包括其形状和长度的影响的理解仍处于起步阶段。因此，飞秒电子束轮廓的能力对于这些新技术的发展至关重要。该提案将通过提供基于史密斯-珀塞尔辐射的单发监测器的概念设计，巩固英国在高梯度粒子加速器领域的科学和技术领导地位。这将使未来的研究在钻石，欧洲核子研究中心和DESY受益的能力，设计和建造的探测器能够监测飞秒电子束的纵向轮廓。这项工作将是基于以前非常令人鼓舞的结果，多拍摄（电子束团平均形状）探测器的发展，由牛津大学的小组FACET，SLAC。该项目旨在逐步从技术开发阶段过渡到技术示范阶段。该拟议项目的基础是已经开展的大量基础研究（部分由STFC在LC-ABD项目下提供支持）以及仍在美国SLAC FACET进行的E203实验（部分由STFC UK（JAI赠款）和能源部（美国）根据（合同DE-AC 02 - 76 SF 00515）提供支持）。目前安装在FACET（SLAC）的E203监视器是一种多点设备。在其操作期间，光栅和空白被顺序地插入，即一个接一个地插入，因此，频谱不能在单次发射中被覆盖。监护仪的设计（即光栅改变力学，信号采集光学）的局限性，使项目的目标不能通过表面的修改来实现，需要进一步的研究和开发，才能设想设计单次拍摄设备。建议项目的最终目标是产生单次拍摄监视器的概念设计，以便从“技术开发”阶段过渡到“技术演示”阶段。.概念设计将适应于满足任何能够产生飞秒（fs）和亚fs电子束的加速器的需求，允许测量带电粒子长束（微聚束）的精细fs结构，特别是我们对支持实验感兴趣：SLAC的FACET，CERN的AWAKE和FlashForward（DESY）。我们将解决的关键问题是：1。新颖的光栅设计，以改善cSPr和背景信号的区分2.监护仪各组成部分的设计3.单次cSPr监测器的概念设计这些也将定义项目的工作包。数据采集（DAQ）将不是本项目的一部分，因为DAQ已在SLAC（美国）为E203实验开发。鉴于该项目的成功完成，长期战略是与商业伙伴合作建造监测器，用于未来的实验。

The need for a longitudinal bunch profile, single shot, detector capable of measuring accurately the longitudinal profile and features of femtosecond single and modulated electron beam is dictated by the rapid developments in the fields of Free Electron Lasers (next generation light sources) and high-gradient particle accelerators. The temporal profiling is needed for an accelerator and FEL performance monitoring and understanding, which determine its ability of coherent x-ray generation and applicability for particle colliders and medical purpose. It is especially important for novel accelerators based on wake-field interactions where understanding of the effect of the initial conditions and environment on electron beam parameters including its shape and length are still in its infancy. Therefore the capability of a femtosecond electron beam profiling is crucial for development of these novel techniques. This proposal will underpin UK science and technology leadership in the area of high gradient particle accelerators by delivering conceptual design of a single shot monitor based on Smith-Purcell radiation. This will enable future research at DIAMOND, CERN and DESY benefit from ability to design and construct the detector capable to monitor the longitudinal profile of femtosecond electron bunches. This work will be based on the previous very encouraging results of multi-shot (electron bunch average shape) detector development by Oxford team for FACET, SLAC. The project aims to gradually move from technology development phase to technology demonstration. The proposed project is underpinned by a considerable amount of basic research already carried out (partially supported by STFC under the LC-ABD project) and still on-going E203 experiment at FACET, SLAC, USA (partially supported by STFC UK (JAI grant) and Department of Energy (USA) under (contract DE-AC02-76SF00515)). The E203 monitor, which is currently installed at FACET (SLAC), is multi-shot device. During its operation the gratings and blank are inserted sequentially i.e. one after another and, hence, the frequency spectrum cannot be covered in a single shot. The design of the monitor (i.e. gratings change mechanics, signal collection optics) is such that project's goal cannot be achieved via superficial modifications and further R&D is necessary before the design of a single-shot device can be envisioned.The ultimate goal of the project proposed is to produce a conceptual design of a single-shot monitor enabling the transition from the "technology development" stage to "technology demonstration". The conceptual design will be adaptable to meet the demands of any accelerator capable generating femtosecond (fs) and sub-fs electron bunches allowing to measure fine fs-structures of long bunches (micro-bunching) of charged particles and in particular we are interested in supporting experiments: FACET at SLAC, AWAKE at CERN and FlashForward (DESY). The key issues which we will address are:1. Novel grating design to improve cSPr and background signals discrimination2. Design of monitor's individual components 3. Conceptual design of the single-shot cSPr monitorThese will also define the work packages of the project. The data acquisition (DAQ) will not be a part of this project as the DAQ has been already developed for E203 experiment at SLAC (USA). Given a successful completion of this project it is the long term strategy to engage with commercial partners in the construction of the monitors for future experiments.