A Method for Measuring Emittance in $e^+ e^-$ Colliding Beams

TL;DR

This paper presents a technique to measure beam emittance and size in electron-positron colliders using collision event data, enabling detailed analysis of beam properties and dynamic effects.

Contribution

The paper introduces a novel method for simultaneous measurement of beam size and angular spread using collision events, improving accuracy at the CESR facility.

Findings

Successful measurement of beam size and angular spread

Extraction of horizontal and vertical emittance values

Detection of dynamic effects in beam behavior

Abstract

We have developed techniques that allow simultaneous measurement of the spatial size of the luminous colliding beam region and the angular spread of beams in collision using e+e- --> mu+mu- events. These are demonstrated at the CLEO interaction point of the Cornell Electron-Positron Storage Ring, CESR, taking advantage of the small and well understood resolution of the CLEO tracking system. These measurements are then used to extract the horizontal beta, horizontal emittance and the vertical emittance and search for dynamic effects at CESR.