Transverse Beam Size Diagnostics using Brownian Nanoparticles

概要

A novel beam diagnostic method based on coherence characterization of synchrotron radiation through the Heterodyne Near Field Scattering (HNFS) technique is presented. HNFS is a self-referencing optical technique based on the interference between the transmitted beam and the spherical waves scattered by an ensemble of nanoparticles suspended in a liquid. The resulting single-particle interferogram shows circular fringes modulated by the spatio-temporal Complex Coherence Factor (CCF) of the radiation. Superposition of a number of these patterns results in a stochastic speckle field, from which spatial and temporal coherence information of the source can be retrieved in near field conditions.
I will describe the basics of this technique and a review of the (few) experimental results available in literature. I will also describe the experimental setup mounted along the hard X-ray pinhole at the ALBA synchrotron light source, and the possibility of transverse electron beam size retrieval from the spatial coherence function of the emitted dipole radiation. I also show preliminary results concerning power spectral density of visible synchrotron radiation as obtained from temporal coherence.