UHE particle detection using the lunar Cherenkov technique aims to detect
nanosecond pulses of Cherenkov emission which are produced during UHE cosmic
ray and neutrino interactions in the Moon's regolith. These pulses will reach
Earth-based telescopes dispersed, and therefore reduced in amplitude, due to
their propagation through the Earth's ionosphere. To maximise the received
signal to noise ratio and subsequent chances of pulse detection, ionospheric
dispersion must therefore be corrected, and since the high time resolution
would require excessive data storage this correction must be made in real time.
This requires an accurate knowledge of the dispersion characteristic which is
parameterised by the instantaneous Total Electron Content (TEC) of the
ionosphere. A new method to calibrate the dispersive effect of the ionosphere
on lunar Cherenkov pulses has been developed for the LUNASKA lunar Cherenkov
experiments. This method exploits radial symmetries in the distribution of the
Moon's polarised emission to make Faraday rotation measurements in the
visibility domain of synthesis array data (i. e. instantaneously). Faraday
rotation measurements are then combined with geomagnetic field models to
estimate the ionospheric TEC. This method of ionospheric calibration is
particularly attractive for the lunar Cherenkov technique as it may be used in
real time to estimate the ionospheric TEC along a line-of-sight to the Moon and
using the same radio telescope.Comment: 4 pages, 2 figures, Proceedings of ARENA 2010, Nantes, France;
doi:10.1016/j.nima.2010.10.12
