In situ radioglaciological measurements near Taylor Dome, Antarctica and implications for ultra-high energy (UHE) neutrino astronomy

Abstract

Radiowave detection of the Cherenkov radiation produced by neutrino-ice collisions requires an understanding of the radiofrequency (RF) response of cold polar ice. We herein report on a series of radioglaciological measurements performed approximately 10 km north of Taylor Dome Station, Antarctica from Dec. 6, 2006 -Dec. 16, 2006. Using RF signals broadcast from: a) an englacial discone, submerged to a depth of 100 meters and broadcasting to a surface dual-polarization horn receiver, and b) a dual-polarization horn antenna on the surface transmitting signals which reflect off the underlying bed and back up to the surface receiver, we have made time-domain estimates of both the real (index-of-refraction "n") and imaginary (attenuation length "Latten") components of the complex ice dielectric constant. We have also measured the uniformity of ice response along two orthogonal axes in the horizontal plane. We observe an apparent wavespeed asymmetry of order 0.1% between two orthogonal linear polarizations projected into the horizontal plane, consistent with some previous measurements, but somewhat lower than others.

Radio-frequency probes of Antarctic ice at South Pole

“…www.the-cryosphere.net/7/855/2013/ (Fujita et al, 1996) Alaska single crystals (1.2 ± 0.2) % 9.7 GHz (Matsuoka et al, 1997) Alaska single crystals ∼ 1.1 % 1 MHz -39 GHz (Matsuoka et al, 1998) Dome Fuji core (0.33 ± 0.0.01)% 33 GHz (Doake et al, 2002) Brunt Ice Shelf (>0.14-0.47) % (Doake et al, 2003) George VI Ice Shelf (>0.05-0.15) % Mizuho measurable 60 MHz and 179 MHz (Fujita et al, 2006) Mizuho (0.5-1.2)% 60 MHz and 179 MHz (Besson et al, 2008) Taylor Dome 0.24 % time-domain (Kravchenko et al, 2010) South Pole 0.31 % time-domain Pulse generator output signal used for the primary measurements described herein. As seen in the figure, the total time delay through the associated cables has been measured to be 194 ns.…”

An in situ measurement of the radio-frequency attenuation in ice at Summit Station, Greenland

“…In this paper, we report an in situ measurement of the radio attenuation length of the bulk glacial ice at Summit Station made using methods similar to those used in previous work (Barwick and others, 2005;Besson and others, 2008;Barrella and others, 2011;Allison and others, 2012;Hanson and others, 2015).…”

“…Attenuation length corresponds to the rate of neutrino detection, so in situ measurements at specific sites are essential. Previous measurements have been made of the radio properties of ice at sites in Antarctica (Taylor Dome, South Pole and the Ross Ice Shelf) to determine the best southern sites for UHE neutrino detection (Barwick and others, 2005;Besson and others, 2008;Barrella and others, 2011;Allison and others, 2012;Hanson and others, 2015), and have found a depth-averaged field attenuation length hL � i at 300 MHz of 1660 þ255 À 120 m over the top 1500 m of ice at South Pole (Allison and others, 2012).…”

Measurement of sound speed vs. depth in South Pole ice for neutrino astronomy

“…The AMANDA [2] and IceCube [3] detectors have been developed to exploit this for optical neutrino detection. Antarctic ice is even more transparent in radio wavelengths [4], [5], and the Radio Ice Cherenkov Experiment (RICE) [6] was operated to search for radio signals from astrophysical neutrinos. In situ measurements of the acoustic attenuation length in South Pole ice are underway [7].…”