Time profile monitor for femtosecond-long electron bunches

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 discrimination
2. Design of monitor's individual components
3. Conceptual design of the single-shot cSPr monitor
These 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.

At present, the UK has a strong track record in both science and engineering areas associated with laser-plasma wakefield acceleration, next generation light sources and compact particle accelerators. It is based on a rapid progress and continues effort of research communities in these fields. To maintain world leading position in the future (10+years) as well as gained over years momentum, the communities working in these area will need to be supported by the development of new monitoring tools capable addressing the challenges which these state-of-the-art devices present to the researchers. This motivated the project proposed which is dedicated to development of a non-destructive, compact and affordable femtosecond, single shot electron bunch profile monitor. The impact of the project will be brought through the support of development of compact particle accelerators and next generation light sources thus directly and indirectly stimulating the development of numerous applications that are envisaged for new charged particle (including proton, positrons, electrons etc.) accelerators and light sources.
Within the next "ten plus" years the next generation of accelerators will have a significant impact on both industry and society. These cover new equipment for cancer treatment and diagnostics, high-technology areas of industry, including communication technology (micro and nano-electronics), security, composite material development, pharmaceutical and medical R&D. The impact can be even wider, as many industrial and societal infrastructures (associated with calibration, alignment and fiducialization of instruments, NHS (medical accelerators and isotope production), security) are strongly reliant on coherent sources of radiation and particle accelerators. These areas stand to benefit from the project proposed which will boost further development of compact particle accelerators capable of producing femtosecond-long (fs-long) electron beams either to generate coherent X-ray, UV or THz radiations.
By improving the understanding of femtosecond electron bunch formation and acceleration, the bunch profile monitor described, will facilitate the development of all the opportunities through boosting the research on the next generation of accelerators, stable sources of high-intensity, coherent radiation from THz to x-ray range. There is, thus, the potential also to transform dramatically a wide area of R&D at universities and industry laboratories by creating table-top sources of coherent radiation that are affordable in terms of space, cost and maintenance. Recent advances in these areas have also created a wide range of new research areas, ranging from environment and food screening, space debris and pollution monitoring, to novel spectroscopic techniques and plasma diagnostics. There are emerging ideas on the possible use of THz radiation to treat life threatening medical conditions including some types of skin cancer.
The proposed monitor will be designed to meet the requirements of the high-gradient accelerators of the near (10+ years) and far (50+ years) future, it will be easily adaptable to meet the requirements of any existing accelerator, for any charged particle beam, provided the bunch length is shorter than a few ps. Because of its relative simplicity, low insertion length in a beam line and relatively low cost, it could be deployed at a number of locations along the beam path. The proposed project would be a significant step in nmonitor development and it fits well with one of the STFC priorities "...the development of new detectors that push technology to the limit". It will contribute to near and long term projects such as ALICE (UK), CLARA (UK) and AWAKE UK/EU (CERN,EU), FACET(SLAC, USA). It will also promote knowledge transfer with potential industrial partners such as TMD (UK), RadiaBeam Technologies (USA) and Tech-X (USA), whose collaboration will be sought by means of specially organised workshops.