Updated results from the RICE experiment and future prospects for ultra-high energy neutrino detection at the south pole

Authors

Ilya Kravchenko, University of Nebraska-LincolnFollow
S. Hussain, University of DelawareFollow
D. Seckel, University of DelawareFollow
Dave Z. Besson, University of Kansas - LawrenceFollow
E. Fensholt, University of Kansas
John P. Ralston, University of KansasFollow
J. Taylor, University of Kansas
Kenneth L. Ratzlaff, University of KansasFollow
R. Young, University of Kansas

Document Type

Article

Date of this Version

2012

Citation

PHYSICAL REVIEW D 85, 062004 (2012); DOI: 10.1103/PhysRevD.85.062004

Comments

Copyright 2012 American Physical Society. Used by permission.

Abstract

The RICE experiment seeks observation of ultra-high energy (UHE; E_v > 10¹⁷ eV) neutrinos interacting in Antarctic ice, by measurement of the radio frequency (RF) Cherenkov radiation resulting from the collision of a neutrino with an ice molecule. RICE was initiated in 1999 as a first-generation prototype for an eventual, large-scale in-ice UHE neutrino detector. Herein, we present updated limits on the diffuse UHE neutrino flux, based on 12 years of data taken between 1999 and 2010. We find no convincing neutrino candidates, resulting in 95% confidence-level model-dependent limits on the flux E²_v dϕ/ dE_v < 0.5 X 10^-6 GeV/(cm² s-sr) in the energy range 10¹⁷ < E_v < 10²⁰ eV, or approximately a twofold improvement over our previously published results. Recently, the focus of RICE science has shifted to studies of radio frequency ice properties as the RICE experimental hardware has been absorbed into a new experimental initiative (the Askaryan Radio Array, or ‘‘ARA’’) at the south pole. ARA seeks to improve on the RICE sensitivity by approximately 2 orders of magnitude by 2017 and thereby establish the cosmogenic neutrino flux. As detailed herein, RICE studies of Antarctic ice demonstrate that both birefringence and internal layer RF scattering result in no significant loss of ARA neutrino sensitivity, and, for the first time, verify in situ the decrease in attenuation length with depth into the Antarctic ice sheet.