An in situ measurement of the radio-frequency attenuation in ice at Summit Station, Greenland

Avva, J. S.; Kovac, J. M.; Miki, C.; Saltzberg, D.; Vieregg, A. G.

doi:10.3189/2015jog15j057

Cited by 41 publications

(67 citation statements)

References 21 publications

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“…However, in the ∼100 m or more below the upper surface of the ice, the snow at the surface slowly transitions from loose snow to glacial ice below in a region called the firn. This firn region represents a density gradient from that of loose snow to that of ice [1,2], corresponding to an index of refraction of n ≈ 1.35 for the snow near the surface to n ¼ 1.78 for bulk ice in the radio frequency range of interest for neutrino detection [3,4]. Furthermore, annual variations in the firn mean that the gradient is not perfectly smooth-there are known layers in the firn, especially evident near the surface [5].…”

Section: Introductionmentioning

confidence: 99%

Measurements and modeling of near-surface radio propagation in glacial ice and implications for neutrino experiments

et al. 2018

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We present measurements of radio transmission in the ∼100 MHz range through a ∼100 m deep region below the surface of the ice at Summit Station, Greenland, called the firn. In the firn, the index of refraction changes due to the transition from snow at the surface to glacial ice below, affecting the propagation of radio signals in that region. We compare our observations to a finite-difference time-domain (FDTD) electromagnetic wave simulation, which supports the existence of three classes of propagation: a bulk propagation ray-bending mode that leads to so-called "shadowed" regions for certain geometries of transmission, a surface-wave mode induced by the ice/air interface, and an arbitrary-depth horizontal propagation mode that requires perturbations from a smooth density gradient. In the non-shadowed region, our measurements are consistent with the bulk propagation ray-bending mode both in timing and in amplitude. We also observe signals in the shadowed region, in conflict with a bulk-propagation-only ray-bending model, but consistent with FDTD simulations using a variety of firn models for Summit Station. The amplitude and timing of our measurements in all geometries are consistent with the predictions from FDTD simulations. In the shadowed region, the amplitude of the observed signals is consistent with a best-fit coupling fraction value of 2.4% (0.06% in power) or less to a surface or horizontal propagation mode from the bulk propagation mode. The relative amplitude of observable signals in the two regions is important for experiments that aim to detect radio emission from astrophysical high-energy neutrinos interacting in glacial ice, which rely on a radio propagation model to inform simulations and perform event reconstruction.

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Section: Introductionmentioning

confidence: 99%

Measurements and modeling of near-surface radio propagation in glacial ice and implications for neutrino experiments

et al. 2018

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“…However, this will have a minimal effect if the propagation loss of the electric field is high. The average field attenuation length of the ice at Summit Station is L α = 1022 +230 −253 m. The measured attenuation length was extrapolated to a frequency of 300 MHz from 75 MHz for comparison with other proposed radio neutrino experiments and averaged over the top 1500 m of ice relevant for neutrino telescopes [9]. The total loss in the electric field strength when combines the losses due to attenuation in the medium with the path loss is shown for three proposed sites in Fig.…”

Section: In-ice Prototype In Greenlandmentioning

confidence: 99%

“…The length and size of the antenna array may also present a challenge for deployment. To address some of these concerns, we conducted two tests in in the ice at Summit Station in Greenland in both June 2013 [9] and June 2015 [10]. With the lower trigger threshold expected from a phased array, the total visible ice volume at low energies will increase.…”

Section: In-ice Prototype In Greenlandmentioning

confidence: 99%

Phased arrays: A strategy to lower the energy threshold for neutrinos

et al. 2017

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Abstract. In-ice radio arrays are optimized for detecting the highest energy, cosmogenic neutrinos expected to be produced though cosmic ray interactions with background photons. However, there are two expected populations of high energy neutrinos: the astrophysical flux observed by IceCube (∼1 PeV) and the cosmogenic flux (∼ 10 17 eV or 100 PeV). Typical radio arrays employ a noise-riding trigger, which limits their minimum energy threshold based on the background noise temperature of the ice. Phased radio arrays could lower the energy threshold by combining the signals from several channels before triggering, thereby improving the signal-to-noise at the trigger level. Reducing the energy threshold would allow radio experiments to more efficiently overlap with optical Cherenkov neutrino telescopes as well as for more efficient searches for cosmogenic neutrinos. We discuss the proposed technique and prototypical phased arrays deployed in an anechoic chamber and at Greenland's Summit Station.

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“…In June 2013, we measured the radiation attenuation length of the ice by comparing the reflected power reflected off the bed rock to the power transmitted by an LPDA [13]. The attenuation length averaged over all depths is 947 +92 −85 m at 75 MHz.…”

Section: Gno Sitementioning

confidence: 99%

Site Characterization and Detector Development for the Greenland Neutrino Observatory

Wissel¹,

Avva²,

Bechtol³

et al. 2016

Proceedings of the 34th International Cosmic Ray Conference — PoS(ICRC2015)

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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).

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An in situ measurement of the radio-frequency attenuation in ice at Summit Station, Greenland

Cited by 41 publications

References 21 publications

Measurements and modeling of near-surface radio propagation in glacial ice and implications for neutrino experiments

Measurements and modeling of near-surface radio propagation in glacial ice and implications for neutrino experiments

Phased arrays: A strategy to lower the energy threshold for neutrinos

Site Characterization and Detector Development for the Greenland Neutrino Observatory

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