A real-time phase-space beam emittance monitoring system

Abstract

An electron beam position and angle monitoring system, ps-BPM, has been shown to be able to measure the electron source position and angle at a single location in a beamline at a synchrotron source. This system uses a monochromator to prepare a photon beam whose energy is at that of the K-edge of an absorber filter. The divergence of the beam from the source gives an energy range that will encompass the K-edge of the filter. A measurement of the centre of the monochromatic beam and the K-edge location through the absorber filter gives the position and angle of the electron source. Here, it is shown that this system is also capable of measuring the source size and divergence at the same time. This capability is validated by measurement as the beam size in the storage ring was changed and by ray-tracing simulations. The system operates by measuring the photon beam spatial distribution as well as a K-edge filtered beam distribution. These additional measurements result in the ability to also determine the electron source size and divergence.

Optimization of a phase-space beam position and size monitor for low-emittance light sources

“…Therefore, a single ray can represent a large number of photons. From the previous studies (Samadi et al, 2019), simulation with 1 Â 10 7 rays gives the same sensitivity as the measurement of source size performed with a flux level of 1.2 Â 10 10 photons Hmrad À1 (where H means horizontal) To achieve the sensitivity shown in Fig. 9(c), simulation with 5 Â 10 8 rays indicates that a flux level of 5.9 Â 10 11 photons Hmrad À1 is needed for measuring the APS-U source size.…”

“…The simulated photon-beam profiles are then analyzed based on the same data-analysis process developed for experimental results (Samadi et al, 2019). The edge profile, f edge (y), shown in Fig.…”

“…The electron-source size, y eSource , can be extracted from the spatial width of the measured K-edge on the detector, edge , by (Samadi et al, 2019)…”

“…A pixel size of a few tens of micrometres is adequate to ensure the accuracy of the source size and divergence measurements. Previous experiments (Samadi et al, 2019) show that a detector with 100 mm pixel size is sufficient to measure third-generation synchrotron source sizes. Overall, the accuracy of the curve-fitting proce- dure is more sensitive to the integrated flux than to the pixel size of the detector.…”

“…The vertical phase-space beam position and size monitor (ps-BPM) system (Samadi et al, 2015(Samadi et al, , 2019 developed at the Canadian Light Source (CLS) has demonstrated the ability to measure the source size and divergence, as well as the source position and angle in the vertical plane, at a single location and time. In this article, we will report on the process of optimizing the ps-BPM system for ultra-small electron-source-size measurements and provide an example for the Advanced Photon Source Upgrade (APS-U) project (Borland et al, 2018).…”