Preliminary study on detection and cleaning of parasitic bunches

To establish a nuclear resonant scattering beamline at the High Energy Photon Source (HEPS), it is essential to develop tools for detection and cleaning of parasitic bunches, for meeting the stringent demands on bunch purity. To this end, a novel time-correlated single-photon counting system was implemented at the electron storage ring of the Beijing Electron–Positron Collider II (BEPCII). The purity deterioration process over a week-long operation was recorded by the system. In this study, the mechanism of impurity growth was analyzed by numerical methods and validated on measurements. The agreement between the experimental results and the calculation was fairly good. Two main sources of parasitic bunches, pre-accelerators and the Touschek scattering were confirmed. A bunch-cleaning technique, based on a sinusoidal signal mixed with a pseudo-square wave, was also developed and implemented, and its capability to improve the bunch purity to the level of 10 –7 was experimentally demonstrated. We present the experimental setup, principle, and measurement results of a system for detection and cleaning of parasitic bunches.