KEKB Beam Collision Stability at the Picosecond Timing and Micron Position Resolution as observed with the Belle Detector

TL;DR

This study analyzes beam collision stability at KEKB using the Belle detector, focusing on timing and position resolution at picosecond and micron scales, revealing effects of beam loading and informing future collider improvements.

Contribution

It provides detailed measurements of collision timing and position behaviors at KEKB, highlighting the impact of beam loading effects and discussing implications for SuperKEKB.

Findings

Collision timing varies with bunch position in the beam train.

Beam loading effects influence collision stability and timing.

Results inform future collider upgrade strategies.

Abstract

Using the Belle detector we study the characteristics of beam collisions at the KEKB 3.5 GeV $e^+$ on 8 GeV $e^-$ asymmetric energy collider. We investigate the collision timing {\tip} and its $z$-coordinate along the beam axis {\zip} as a function of the position of the colliding bunch in a beam train. The various {\tip} and {\zip} behaviors observed by Belle are attributed to beam loading effects in the radio frequency cavities that accelerate the beams with a beam abort gap. We report these results in detail and discuss the prospects for the SuperKEKB collider.