Suwada, T. JACoW Publishing Geneva, Switzerland 2673-5350 978-3-95450-230-1 10.18429/JACoW-IBIC2021-WEPP12 English 392-395 coupling impedance linac positron electron Contribution to a conference proceedings 2021 2021-10 https://doi.org/10.18429/JACoW-IBIC2021-WEPP12 https://jacow.org/ibic2021/papers/wepp12.pdf The direct simultaneous detection of electron (e-) and positron (e+) bunch signals was successfully performed for the first time by a wideband beam monitor at the positron capture section of the SuperKEKB factory. This monitor can measure a time interval between the e⁻ and e⁺ bunches, their bunch lengths, bunch intensities, and transverse beam positions, depending on the phase of accelerating structures. For this purpose, a new beam monitor with wideband pickups simply using SMA feedthroughs and a wideband detection system based on a fast and real-time oscilloscope was developed to investigate their capture process at the capture section and to maximally optimize the e⁺ intensity. The required specification for the new monitor is to simultaneously detect the e⁺ and e⁻ bunches generated in the capture section within the resolution of pico-second level with a sufficient dynamic range in the time-interval and bunch-length measurements. Thus, the wideband detection system is required for this purpose. In this report, the basic design and results based on a modal analysis of electromagnetic couplings between the SMA-feedthrough electrode and a beam are in detail given along with some obtained performance.