Towards a Measurement of the $e^+e^-$ Flux above 1 TeV with HAWC

TL;DR

This paper discusses how the HAWC observatory can measure the flux of high-energy electrons and positrons above 1 TeV, using topological cuts to distinguish electromagnetic showers from hadronic cosmic rays.

Contribution

It presents the sensitivity of HAWC to leptonic cosmic rays and explores methods for measuring the combined $e^+e^-$ flux and separating electron and positron signals.

Findings

HAWC can detect electron and positron showers above 1 TeV from two-thirds of the sky daily.

Topological cuts effectively suppress hadronic cosmic ray background.

Potential for charge separation of electrons and positrons with HAWC is discussed.

Abstract

The High-Altitude Water Cherenkov (HAWC) Observatory records the air showers produced by cosmic rays and gamma rays at a rate of about 20 kHz. While the events observed by HAWC are 99.9% hadronic cosmic rays, this background can be strongly suppressed using topological cuts that preferentially select electromagnetic air showers. Using this capability of HAWC, we can create a sample of air showers dominated by gamma rays and cosmic electrons and positrons. HAWC is one of the few operating observatories capable of measuring showers produced by electron and positron primaries above 1 TeV, and can record these showers from two-thirds of the sky each day. We describe the sensitivity of HAWC to leptonic cosmic rays, and discuss prospects for the measurement of the combined $e^+e^-$ flux and possible approaches for positron and electron charge separation with the HAWC detector.