Constraints on the diffuse flux of ultrahigh energy neutrinos from four years of Askaryan Radio Array data in two stations

• Main Authors: Allison, P, Archambault, S, Beatty, JJ, Beheler-Amass, M, Besson, DZ, Beydler, M, Chen, CC, Chen, CH, Chen, P, Clark, BA, Clay, W, Connolly, A, Cremonesi, L, Davies, J, de Kockere, S, de Vries, KD, Deaconu, C, DuVernois, MA, Friedman, E, Gaior, R, Hanson, J, Hanson, K, Hoffman, KD, Hokanson-Fasig, B, Hong, E, Hsu, SY, Hu, L, Huang, JJ, Huang, M-H, Hughes, K, Ishihara, A, Karle, A, Kelley, JL, Khandelwal, R, Kim, K-C, Kim, M-C, Kravchenko, I, Kurusu, K, Landsman, H, Latif, UA, Laundrie, A, Li, C-J, Liu, T-C, Lu, M-Y, Madison, B, Mase, K, Meures, T, Nam, J, Nichol, RJ, 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, GS, Vieregg, AG, Wang, M-Z, Wang, S-H, Wissel, SA, Yoshida, S, Young, R
• Format: Article in Journal/Newspaper
• Language: English
• Published: AMER PHYSICAL SOC 2020
• Subjects: Antarctic; Antarc*
• Online Access: https://discovery.ucl.ac.uk/id/eprint/10109785/1/PhysRevD.102.043021.pdf; https://discovery.ucl.ac.uk/id/eprint/10109785/

The Askaryan Radio Array (ARA) is an ultrahigh 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 ultrahigh energy neutrinos between 10^{16} and 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 x 10^{-16} cm^{-2}s^{-1}sr^{-1}. This analysis includes four times the exposure of the previous ARA result and represents approximately 1/5th he exposure expected from operating ARA until the end of 2022.