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Home > Physics > Research > Particle Physics > John Adams Institute > Investigation of electromagnetic radiation characteristics generated by charged particles
More in this section Karataev Pavel

Investigation of electromagnetic radiation characteristics generated by charged particles

Coherent Diffraction and Synchrotron Radiation as a tool for non-invasive longitudinal electron beam profile monitoring

Modern accelerator installations such as Large Hadron Collider, 3rd Generation Light Sources (Synchrotron Radiation Storage Rings), 4th Generation Light Sources (X-ray Free electron Lasers) or even modest size ones used for medical or industrial applications would never work without a set of diagnostic equipment enabling scientists to know where the particle beam is, how big, how fast or how dense it is. Modern and future accelerators imply to solve challenging scientific problems by means of very high quality beams, which implies to develop precise diagnostics to control those beams as well as experiments.

Longitudinal charged particle beam profile monitoring is one of the challenging tasks which we are trying to pursue within our group. We know that if the beam of particles emits radiation with wavelength comparable to or longer than the bunch length all particles emit radiation more or less in time, i.e. coherently. As a result the radiation spectrum bears information about longitudinal structure of the bunch. By measuring the radiation spectrum precisely we can decode the information about the bunch length and study the longitudinal dynamics of the charged particle beams.

We use two mechanisms for radiation production: Synchrotron Radiation can be easily generated in circular accelerators and Diffraction Radiation can be easily generated in linear ones.

The project aims to develop an advanced spectrometer system which will be used for longitudinal electron beam dynamics studies in one of the world's leading accelerator facilities such as CERN (Switzerland) or Diamond (UK).

Optical Diffraction Radiation as a tool for transverse beam size measurements

Diffraction Radiation (DR) appears when a charged particle moves in the vicinity of a medium, i.e. moves through a slit in a screen. Only the electric field of the particle interacts with the target medium. It minimises the energy losses experienced by the particle and allows us to keep the beam parameters almost the same as the initial ones. On the other hand the DR spatial distribution significantly depends on the transverse particle beam dimensions. By analysing the DR angular distribution in optical wavelength range one may decode information about the transverse beam parameters. Since the energy losses are minimal we can develop a non-invasive transverse beam size monitor which is required for future accelerators such as linear collider or X-ray free electron lasers where the particle losses are limited.

Development of an Ultra-fast Room Temperature Highly Sensitive THz Detection Systems for Security and Accelerator Science Applications

Detection of electromagnetic radiation is a key issue in EM radiation physics. In accelerators detectors must be fast, simple to use, robust and reliable. Fast detection gives an opportunity to quickly determine the charged particle beam parameter and develop a feedback system to improve the parameter if necessary. To measure millimetre wave radiation quickly we have launched a programme jointly with Rutherford Appleton Laboratory on the development of an ultra-fast room temperature highly-sensitive detector based on Schottky Barrier Diode. The diode is a metal-semiconductor barrier which has an extremely fast response when a far infra-red power arrives. The project will aim to design the electronics for the diode detector, manufacturing and testing it on a bench in RAL and Royal Holloway, and applying it for microbunch instability studies in Diamond Storage Ring.

Visualisation of Electromagnetic Radiation Process using Sophisticated Simulation Tools for Application in Charged Particle Beam Diagnostics.   

To be able to develop an advanced diagnostic tool for future accelerators it is necessary to optimise its performance. To choose a proper experimental hardware experimentally is impractical and expensive. Therefore it is important to be able to predict the performance of a device. Unfortunately the EM radiation theories developed so far are rather idealised. They allow us to make general estimations but not detailed simulations essential at the design stage.     

Within the group we have access to an  Advanced Simulation Suite developed at the Stanford Linear Accelerator Centre and installed at Franklin cluster in NURSC (US). We also have a GDfidl simulation package installed at a 200 core cluster at Royal Holloway. The aim of the project is to visualise the EM radiation process from a charged particle passing by different targets and extend the simulations beyond the existing theoretical approaches.


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