• Hwang, J.-G.; Schiwietz, G.; Goslawski, P.; Ries, M.: Beam halo measurements for specialbunches in a storage ring by using a coronagraph. Review of Scientific Instruments 92 (2021), p. 123302/1-9

Open Accesn Version

We demonstrate an experimental methodology for measuring the halo distribution of special bunches in a storage ring using a synchrotronradiation coronagraph composed of the objective lens and a re-diffraction system. The optimum parameters for the coronagraph were inves-tigated within several boundary conditions by applying a paraxial Fourier transformation sequentially from one plane to the next plane. Inaddition, the effect of Mie-scattering was estimated for different polishing-quality lenses and it shows that a high-quality lens is capable ofachieving a dynamic range of the monitor of about 104. The capability of the halo monitor has been demonstrated by measuring the hori-zontal particle distribution of special bunches in beam experiments at the BESSY II storage ring. This monitor offers a new opportunity forcontinuous monitoring of special bunches in the storage ring such as transverse resonance island buckets and pulse-picking by resonant excitation, which open new horizons for storage rings that are capable of sophisticated experiments using a single bunch signal as well as servinghigh-flux users simultaneously.