Design and initial performance of the Askaryan Radio Array prototype EeV neutrino detector at the South Pole

Abstract

We report on studies of the viability and sensitivity of the Askaryan Radio Array (ARA), a new initiative to develop a Teraton-scale ultra-high energy neutrino detector in deep, radio-transparent ice near Amundsen-Scott station at the South Pole. An initial prototype ARA detector system was installed in January 2011, and has been operating continuously since then. We report on studies of the background radio noise levels, the radio clarity of the ice, and the estimated sensitivity of the planned ARA array given these results, based on the first five months of operation. Anthropogenic radio interference in the vicinity of the South Pole currently leads to a few-percent loss of data, but no overall effect on the background noise levels, which are dominated by the thermal noise floor of the cold polar ice, and galactic noise at lower frequencies. We have also successfully detected signals originating from a 2.5 km deep impulse generator at a distance of over 3 km from our prototype detector, confirming prior estimates of kilometer-scale attenuation lengths for cold polar ice. These are also the first such measurements for propagation over such large slant distances in ice. Based on these data, ARA-37, the 200 km 2 array now under construction, will achieve the highest sensitivity of any planned or existing neutrino detector in the 10 16 − 10 19 eV energy range.

First results from two deep Askaryan Radio Array stations

“…The above effect has been verified in beam tests for various materials including ice [6]. In radio-transparent media like South Pole ice, radio waves have an attenuation length of more than 800 m which allows for the survey of a large volume with a relatively small number of sensors and thus for the cost effective construction of a neutrino detector [7].…”

“…To minimize overlap between stations and, thus, maximize the effective area of the full detector the stations are distributed in a hexagonal structure with a spacing of 2 km. More details about the ARA stations and their performance can be found in [7,9]. Currently, 3 ARA stations and a prototype are deployed at the South Pole.…”

Ultra High Energy Cosmic Rays and Neutrinos

“…In figure 7 we also plot the experimental data of Auger (red points) and TA (black points) and the expected sensitivities of ARA (thick solid blu line), a future neutrino observatory based on the Askarian effect [40], and JEM-EUSO (thick solid red line), an UHECR detector planned onboard the international space station [41]. The fluxes of UHECR produced by SHDM decay are plotted as solid lines (red for neutrinos, blu for gamma-rays and green from protons), these fluxes are obtained in the case of an inflationary potential β = 2 and a ratio of tensor to scalar modes r = 0.05 that corresponds to a SHDM mass M X = 4.5 × 10 13 GeV (as labeled in the plot).…”

Invited Article: miniTimeCube

“…The IRS has been used in a variety of projects that require fast sampling and deep buffering. [29][30][31] The IRS ASIC architecture is shown schematically in Fig. 17, and a list of operating parameters can be found in Table III.…”