Optimization of Future Accelerators – paper published

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Accurate measurements of the transverse beam properties are essential to understand and optimise particle beams. Emittance reconstruction from the 4D transverse phase space beam matrix is challenging in the presence of cross-plane coupling and measurement errors, and require the use of optimised methods. In a recent paper, co-authored by Dr Javier Resta Lopez, a senior Marie Curie Fellow in the QUASAR group and colleagues from The University of Valencia in Spain, general conditions of solvability of the systems of equations involved in the process of emittance reconstruction are analytically studied for an arbitrary number of measurement stations in diagnostics sections of linear accelerators and transfer lines.

The results described in this paper are relevant for the optimisation of the optical lattice of diagnostics sections to measure both the projected emittance (2D) and the so-called intrinsic emittance (4D). The conditions obtained can be extremely useful for the design of robust algorithms to avoid imaginary solutions in the presence of strong systematic errors and transverse cross-plane coupling. Measurements of projected and intrinsic emittances have been done at the Accelerator Test Facility 2 (ATF2) at KEK in Japan using a multi-Optical Transition Radiation system (m-OTR) made of four measurement stations, and compared with simulations for different coupling scenarios. The results and conclusions obtained in this paper are highly relevant for the design and optimisation of diagnostics sections in Future Linear Colliders, Free Electron Lasers and transfer lines in general.

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A. Faus-Golfe, J. Navarro, N. Fuster Martinez, J. Resta Lopez, J. Giner Navarro, “Emittance reconstruction from measured beam sizes in ATF2 and perspectives for ILC,” NIM A 819 (2016) 122-138.