Study of electromagnetic backgrounds in the 25-300 MHz frequency band at the South Pole

TL;DR

This study measures electromagnetic backgrounds at 25-300 MHz at the South Pole to assess the feasibility of radio detection of air showers and background noise for neutrino detection.

Contribution

It provides the first detailed electromagnetic background measurements at the South Pole for radio air shower detection and tests a self-trigger strategy with multiple antennas.

Findings

Low electromagnetic background promising for radio air shower detection

Identification of pulsed radio interferences that mimic real signals

Implementation of a multi-antenna self-trigger system planned

Abstract

Extensive air showers are detectable by radio signals with a radio surface detector. A promising theory of the dominant emission process is the coherent synchrotron radiation emitted by e+ e- shower particles in the Earth's magnetic field (geosynchrotron effect). A radio air shower detector can extend IceTop, the air shower detector on top of IceCube. This could increase the sensitivity of IceTop to higher shower energies and for inclined showers significantly. Muons from air showers are a major part of the background of the neutrino telescope IceCube. Thus a surface radio air shower detector could act as a veto detector for this muonic background. Initial radio background measurements with a single antenna in 2007 revealed a continuous electromagnetic background promising a low energy threshold of radio air shower detection. However, short pulsed radio interferences can mimic real signals and have to be identified in the frequency range of interest. These properties of the electromagnetic background was being measured at the South Pole during the Antarctic winter 2009 with two different types of surface antennas. In total four antennas are placed at distances ranging up to 400m from each other. In 2010 a small eight channel surface detector will test an amplitude threshold self trigger strategy with large dipole antennas on the South Pole snow ground. The installation will be described.