First Array-Wide Search for Diffuse UHE Neutrinos with the Askaryan Radio Array

Muzio, Marco; ARA Collaboration,; Alden, N.; Ali, S.; Allison, P.; Archambault, S.; Beatty, J.J.; Besson, D.Z.; Bishop, A.; Chen, P.; Chen, Y.C.; Chen, Y.-C.; Chiche, S.; Clark, B.A.; Connolly, A.; Couberly, K.; Cremonesi, L.; Cummings, A. C.; Dasgupta, P.; Debolt, R.; De Kockere, S.; de Vries, K.D.; Deaconu, C.; DuVernois, M.A.; Flaherty, J.; Friedman, E.; Gaior, R.; Giri, P.; Hanson, J.; Harty, N.; Hoffman, K.D.; Huang, M.-H. A.; Hughes, K.; Ishihara, A.; Karle, A.; Kelley, J.L.; Kim, K.-C.; Kim, M.-C.; Kravchenko, I.; Krebs, R.; Kuo, C.Y.; Kurusu, K.; Latif, U.A.; Liu, C.H.; Liu, T.C.; Luszczak, W.; Machtay, A.; Mase, K.; Muzio, M.S.; Nam, J.; Nichol, R.J.; Novikov, A.; Nozdrina, A.; Oberla, E.; Pai, C.W.; Pan, Y.; Pfendner, C.; Punsuebsay, N.; Roth, J.; Salcedo-Gomez, A.; Seckel, D.; Seikh, M.F.H.; Shiao, Y.-S.; Su, S.C.; Toscano, S.; Torres, J.; Touart, J.; van Eijndhoven, N.; Vieregg, A.; Vilarino Fostier, M.; Wang, M.-Z.; Wang, S.-H.; Windischhofer, P.; Wissel, S.A.; Xie, C.; Yoshida, S.; Young, R.

doi:10.22323/1.501.1126

Abstract

The Askaryan Radio Array (ARA) is an ultrahigh energy (UHE) neutrino detector at the South Pole, designed to search for radio pulses emitted by neutrino-initiated particle showers in ice. ARA consists of an array of five autonomous stations with 2 km spacing. Each station consists of 16 radio antennas embedded ${\sim}200$ m deep in the ice that are sensitive to either vertically- or horizontally-polarized signals. Radio arrays like ARA represent a cost-efficient means of achieving the enormous detection $O(10~\text{km}^3)$ volumes necessary for UHE neutrino detection. This contribution presents the current status of the first-ever array-wide search for UHE neutrinos, leveraging ARA’s unprecedented ${\sim}28$ station-years of livetime. This search will have the best sensitivity of any neutrino detector above $3$ EeV, sufficient to probe the $220$ PeV flux inferred from KM3NeT's observation of KM3-230213A. Importantly, this study demonstrates the feasibility of array-wide neutrino searches, which are necessary for next-generation detectors, like RNO-G (35 stations planned) and IceCube-Gen2 Radio (361 stations proposed), to achieve their design sensitivity. We discuss the progress towards a fully analyzed sample and improvements to ARA’s detector characterization and analysis sensitivity.