Longitudinal phase-space diagnostics using a stripline-type beam-timing monitor at the KEKB injector linac

Abstract

Abstract A new beam-timing monitor (BTM) has been developed to analyze the longitudinal beam dynamics and bunching characteristics at the pre-injector of the KEKB injector linear accelerator (linac). The BTM is a conventional stripline-type beam monitor with two pickup electrodes. It measures the relative time delay between the arrival time of the beam signal and 1st-zero-cross time of the fundamental accelerating radio frequency (rf) signal (2856 MHz) immediately after the detection of the beam signal. The beam tests were performed to evaluate the performance and characteristics of the BTM for primary single-bunched electron beams with high bunch charges of ∼ 8 nC for positron production. It was found that the results show that the resolution in the delay-time measurement is σ ∼ 1.2 ps in one standard deviation. This report describes the basic design of the BTM system, the beam tests, and results in detail, to investigate the sensitivity and stability of the beam timing based on the longitudinal phase-space parameters at the pre-injector and location A1 of the injector linac, along with the calibration method in the pulse-height variation of the BTM signal.