Design of synchrotron radiation interferometer (SRI) for beam size measurement at visible diagnostics beamline in Indus-2 SRS

The measurement of transverse beam size in new generation synchrotron radiation sources (SRSs) is a challenging task due to their small beam emittance and low couplings. Beam size measurement by imaging of visible synchrotron radiation (SR) is limited by diffraction. Nowadays, advanced accelerators are opting for synchrotron radiation interferometer (SRI) to measure the beam size through the analysis of the spatial coherence of the visible SR light. It has a superior spatial resolution and can measure transversal beam size down to few microns with visible light. Transverse emittance can also be evaluated from the measured beam size by using Twiss parameters of machine. In this paper, we have described the design details of the proposed double-slit SRI in Indus-2, system simulation using synchrotron Radiation Workshop (SRW) and visibility analysis of interferogram by horizontal and vertical curve fittings. This work will be useful during low emittance operations of Indus-2 and for future high brightness SRS in India. SRI can provide measurement of very small beam sizes and full reconstruction of the beam profile. This technique also provides bunch resolved measurement with detector gating, which are useful for studies of injection dynamics, transverse instabilities, intra beam scattering etc.