First Simultaneous Detection of Electron and Positron Bunches at the Positron Capture Section of the SuperKEKB Factory

Abstract

The direct simultaneous detection of electron and positron bunch signals was successfully performed for the first time with wideband pickups and a detection system at the positron capture section of the SuperKEKB factory. The time interval between the electron and positron bunches, their bunch lengths, and bunch intensities depending on the phase of accelerating structures were measured to investigate their capture process and to maximally optimize the positron intensity. The results show that the time intervals were measured in the range of 135–265 ps, and the line-order switch of the electron and positron bunches in the axial direction was clearly observed as a function of the phase. The positron (electron) intensity was maximized at the optimal phase (180 deg shifted from the optimum). These series of measurements have never been experimentally conducted so far. It is demonstrated that the positron intensity can be systematically optimized with this system as functions of beam parameters in multidimensional spaces for any positron capture section.

Positron Sources for Future High Energy Physics Colliders

“…The main limit in conventional sources is the heat load on the target which limits the power of the primary beam. The SuperKEKB positron source is the highest intensity positron source in operation, thanks to improvements on the drive beam parameters, the flux concentrator used to capture the beam and improvements in the positron line diagnostics [20,21].…”

Positron sources: from conventional to advanced accelerator concepts-based colliders

“…• Development of the very fast response BPM [50]. It allowed monitoring the positron beam in the beginning of the capture section.…”