Site Characterization and Detector Development for the Greenland Neutrino Observatory

Abstract

The PeV neutrinos discovered by IceCube are of astrophysical origin, and their progenitors could be any of several source classes, including active galactic nuclei, gamma-ray bursts, or pulsars. Such high-energy accelerators would produce neutrinos up to hundreds of PeV, which motivates the development of neutrino telescopes with the sensitivity, energy resolution, and pointing resolution required to distinguish among models of the IceCube neutrinos as well as cosmogenic neutrinos. Radio detection of Askaryan radiation from neutrino showers in ice is well-suited to the detection of the highest energy neutrinos, with degree-scale pointing resolution and the ability to build sparse arrays, but the energy threshold of current experiments is currently set by the temperature of the ice. The uncorrelated thermal noise can be reduced by combining the signals from several antennas in a phased array. We report here on a June 2015 trip to Summit Station In Greenland for testing a phased array of dipoles, as well as the sensitivity of the array and background measurements of the site and discuss prospects for the Greenland Neutrino Observatory (GNO).

Design and sensitivity of the Radio Neutrino Observatory in Greenland (RNO-G)

“…[35][36][37][38][39]. First efforts at exploring the feasibility of a detector in Greenland have been conducted previously by members of the collaboration [40][41][42] and have encouraged the development of RNO-G.…”

Development toward a ground-based interferometric phased array for radio detection of high energy neutrinos

“…An instrument was deployed at Summit Station in June 2015 to characterize the site and validate the phased array technique with an array deployed in the ice, as discussed in Reference [21]. The system used analog beamforming to combine signals from multiple antennas, as shown in the schematic of the RF signal chain in Figure 11.…”

Progress in the Development of Radio-Cherenkov Neutrino Detectors

“…Undeterred, Vieregg, Bechtol, and Romero-Wolf [50] described a new idea to incorporate beam-form techniques in radio-cherenkov neutrino detectors. They and collaborators reported the first results of in situ testing at a Greenland site [16]. Researchers lowered a string of 8 dipole antennas to a depth of 115 m, and sent a pulse from a transmitter at a distance of 168 m from the borehole.…”

“…Neutrinos interact so infrequently that a realistic detector must encompass or survey an enormous number of target nuclei, and the target medium must be transparent to the electromagnetic signals generated by the interaction. Several large projects (AMANDA [10], ANITA [11], IceCube [12], and RICE [13] and new concepts under development, such as ARIANNA [14], ARA [15] , and GNO [16] ) exploit the fact that polar ice is transparent to radio and optical emission. Indirect evidence for cosmogenic neutrinos is provided by the Auger [17], HiRes [18] and Telescope Array [19] [20] collaborations, who have reported flux suppression in cosmic ray spectra at the very highest energies.…”

“…The sensitivity of Auger and Telescope Array, which detect tau-neutrinos, and IceCube will improve with continued operation, but thus far cosmogenic neutrinos have not been observed after years of operation. This paper reviews several efforts to increase the sensitivity to neutrinos above 10 17 eV: ARIANNA [14], ARA [15], GNO [16] and GRAND [31], a new concept to observe radio emission from the atmospheric cascade of tau-decay. We will address the relative merits of the frontrunners in a later section.…”