Electron beam characterization with beam loss monitors in AWAKE

TL;DR

This paper introduces a method using beam loss monitors to measure the transverse size and position of electron or proton beams near plasma wakefield injection points, aiding in beam optimization.

Contribution

The paper presents a novel diagnostic technique with less than 10% uncertainty for beam size measurement in plasma wakefield experiments at CERN.

Findings

Transverse beam size measurements agree with beam optics predictions.

Confirmed Earth's magnetic field deflects 18 MeV electron beams.

Method improves beam injection accuracy in AWAKE.

Abstract

We present a method to measure transverse size and position of an electron or proton beam, close to the injection point in plasma wakefields, where other diagnostics are not available. We show that transverse size measurements are in agreement with values expected from the beam optics with a $< 10\%$ uncertainty. We confirm the deflection of the low-energy 18 MeV electron beam trajectory by the Earth's magnetic field. This measurement can be used to correct for this effect and set proper electron bunch injection parameters. The advanced wakefield experiment at CERN (AWAKE) relies on these measurements for optimizing electron injection.