Calculation of the effect of slit size on emittance measurements made by a two-slit scanner

TL;DR

This paper analyzes how finite slit sizes in two-slit scanners affect emittance measurements of particle beams, providing formulas to correct measured values for more accurate results.

Contribution

It derives a formula to recover true emittance from measurements affected by finite slit sizes in Gaussian beam conditions.

Findings

Finite slit sizes cause measurable deviations in emittance readings.

A correction formula enables accurate emittance estimation from measured data.

The approach improves precision in beam diagnostics.

Abstract

Parallel slit-slit devices are commonly used to measure the transverse emittance of a particle beam, selecting a portion of the beam with the front slit and measuring the angular distribution with the rear. This paper calculates the effect of finite slit sizes on measured emittance and Twiss functions in the case of Gaussian spatial and angular distributions of the oncoming beam. A formula for recovering the true emittance from the measured values is derived.