Small air showers in IceTop

TL;DR

This paper describes a method to detect lower-energy cosmic ray air showers using IceTop by selecting events triggering exactly three or four adjacent stations, lowering the energy threshold to 150 TeV for better overlap with direct measurements.

Contribution

It introduces a new selection technique for IceTop data that reduces the energy threshold to 150 TeV, enabling studies in an energy region previously less accessible.

Findings

Extended the energy threshold down to 150 TeV.

Demonstrated the effectiveness of selecting contained events.

Improved overlap with direct cosmic ray measurements.

Abstract

IceTop is an air shower array that is part of the IceCube Observatory currently under construction at the geographic South Pole. When completed, it will consist of 80 stations covering an area of 1 km2. Previous analyzes done with IceTop studied the events that triggered five or more stations, leading to an effective energy threshold of about 0.5 PeV. The goal of this study is to push this threshold lower, into the region where it will overlap with direct measurements of cosmic rays which currently have an upper limit around 300TeV.We select showers that trigger exactly three or exactly four adjacent surface stations that are not on the periphery of the detector (contained events). This extends the energy threshold down to 150TeV.