Constraints on the Diffuse Flux of Ultra-High Energy Neutrinos from Four Years of Askaryan Radio Array Data in Two Stations

• Main Authors: ARA Collaboration, Allison, P., Archambault, S., Beatty, J. J., Beheler-Amass, M., Besson, D. Z., Beydler, M., Chen, C. C., Chen, C. H., Chen, P., Clark, B. A., Clay, W., Connolly, A., Cremonesi, L., Davies, J., de Kockere, S., de Vries, K. D., Deaconu, C., Duvernois, M., Friedman, E., Gaior, R., Hanson, J., Hanson, K., Hoffman, K. D., Hokanson-Fasig, B., Hong, E., Hsu, S. Y., Hu, L., Huang, J. J., Huang, M. -H., Hughes, K., Ishihara, A., Karle, A., Kelley, J. L., Khandelwal, R., Kim, K. -C., Kim, M. -C., Kravchenko, I., Kurusu, K., Landsman, H., Latif, U. A., Laundrie, A., Li, C. -J., Liu, T. -C., Lu, M. -Y., Madison, B., Mase, K., Meures, T., Nam, J., Nichol, R. J., Nir, G., Novikov, A., Nozdrina, A., Oberla, E., O'Murchadha, A., Osborn, J., Pan, Y., Pfendner, C., Roth, J., Sandstrom, P., Seckel, D., Shiao, Y. -S., Shultz, A., Smith, D., Torres, J., Touart, J., van Eijndhoven, N., Varner, G. S., Vieregg, A. G., Wang, M. -Z., Wang, S. -H., Wissel, S. A., Yoshida, S., Young, R.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: arXiv 2019
• Subjects: High Energy Astrophysical Phenomena astro-ph.HE; Instrumentation and Methods for Astrophysics astro-ph.IM; FOS Physical sciences; Antarctic; Antarc*
• Online Access: https://dx.doi.org/10.48550/arxiv.1912.00987; https://arxiv.org/abs/1912.00987

The Askaryan Radio Array (ARA) is an ultra-high energy (UHE, $>10^{17}$ eV) neutrino detector designed to observe neutrinos by searching for the radio waves emitted by the relativistic products of neutrino-nucleon interactions in Antarctic ice. In this paper, we present constraints on the diffuse flux of ultra-high energy neutrinos between $10^{16}-10^{21}$ eV resulting from a search for neutrinos in two complementary analyses, both analyzing four years of data (2013-2016) from the two deep stations (A2, A3) operating at that time. We place a 90 % CL upper limit on the diffuse all flavor neutrino flux at $10^{18}$ eV of $EF(E)=5.6\times10^{-16}$ $\textrm{cm}^{-2}$$\textrm{s}^{-1}$$\textrm{sr}^{-1}$. This analysis includes four times the exposure of the previous ARA result, and represents approximately 1/5 the exposure expected from operating ARA until the end of 2022. : 12 pages, 7 figures; Accepted to PRD