T. Meures

Performance of two Askaryan Radio Array stations and first results in the search for ultrahigh energy neutrinos

Ultrahigh energy neutrinos are interesting messenger particles since, if detected, they can transmit exclusive information about ultrahigh energy processes in the Universe. These particles, with energies above 1016 eV, interact very rarely. Therefore, detectors that instrument several gigatons of matter are needed to discover them. The ARA detector is currently being constructed at the South Pole. It is designed to use the Askaryan effect, the emission of radio waves from neutrino-induced cascades in the South Pole ice, to detect neutrino interactions at very high energies. With antennas distributed among 37 widely separated stations in the ice, such interactions can be observed in a volume of several hundred cubic kilometers. Currently three deep ARA stations are deployed in the ice, of which two have been taking data since the beginning of 2013. In this article, the ARA detector “as built” and calibrations are described. Data reduction methods used to distinguish the rare radio signals from overwhelming backgrounds of thermal and anthropogenic origin are presented. Using data from only two stations over a short exposure time of 10 months, a neutrino flux limit of 1.5 × 10−6 GeV=cm2=s=sr is calculated for a particle energy of 1018 eV, which offers promise for the full ARA detector.

Design and performance of the South Pole Acoustic Test Setup

The South Pole Acoustic Test Setup (SPATS) was built to evaluate the acoustic characteristics of the South Pole ice in the 10-100 kHz frequency range, for the purpose of assessing the feasibility o ...

The cosmic-ray air-shower signal in Askaryan radio detectors

We discuss the radio emission from high-energy cosmic-ray induced air showers hitting Earths surface before the cascade has died out in the atmosphere. The induced emission gives rise to a radio signal which should be detectable in the currently operating Askaryan radio detectors built to search for the GZK neutrino flux in ice. The in-air emission, the in-ice emission, as well as a new component, the coherent transition radiation when the particle bunch crosses the air-ice boundary, are included in the calculations.

An extended-range Ethernet and clock distribution circuit for distributed sensor networks

This paper describes a high-speed Ethernet-based data and clock network for applications which require an array of multiple sensor nodes distributed over distances of up to 250 m from a central hub. Speeds of up to 100 Mbit/sec and clock skew at the level of 50 ps are achievable using commercially available network-grade twisted pair cables and low-power Ethernet transceiver circuits. No fiber optic components are necessary. A specific application of this technology is presented: the ARA neutrino telescope located at the South Pole.

Research and calibration of acoustic sensors in ice within the SPATS (South Pole Acoustic Test Setup) project

We present development work aiming towards a large scale ice-based hybrid detector including acoustic sensors for the detection of neutrinos in the GZK range. A facility for characterization and calibration of acoustic sensors in clear (bubble-free) ice has been developed and the first measurements done at this facility are presented. Further, a resonant sensor intended primarily for characterization of the ambient noise in the ice at the South Pole has been developed and some data from its performance are given

Measurement of the multi-TeV neutrino interaction cross-section with IceCube using Earth absorption

Neutrinos interact only very weakly, so they are extremely penetrating. The theoretical neutrino–nucleon interaction cross-section, however, increases with increasing neutrino energy, and neutrinos with energies above 40 teraelectronvolts (TeV) are expected to be absorbed as they pass through the Earth. Experimentally, the cross-section has been determined only at the relatively low energies (below 0.4 TeV) that are available at neutrino beams from accelerators. Here we report a measurement of neutrino absorption by the Earth using a sample of 10,784 energetic upward-going neutrino-induced muons. The flux of high-energy neutrinos transiting long paths through the Earth is attenuated compared to a reference sample that follows shorter trajectories. Using a fit to the two-dimensional distribution of muon energy and zenith angle, we determine the neutrino–nucleon interaction cross-section for neutrino energies 6.3–980 TeV, more than an order of magnitude higher than previous measurements. The measured cross-section is about 1.3 times the prediction of the standard model, consistent with the expectations for charged- and neutral-current interactions. We do not observe a large increase in the cross-section with neutrino energy, in contrast with the predictions of some theoretical models, including those invoking more compact spatial dimensions or the production of leptoquarks. This cross-section measurement can be used to set limits on the existence of some hypothesized beyond-standard-model particles, including leptoquarks.

Probing the radar scattering cross-section for high-energy particle cascades in ice

Recently the radar scattering technique to probe neutrino induced particle cascades above PeV energies in ice was investigated. The feasibility of the radar detection method was shown to crucially depend on several up to now unknown plasma properties, such as the plasma lifetime and the free charge collision rate. To determine these parameters, a radar scattering experiment was performed at the Telescope Array Electron Light Source facility, where a beam of high-energy electrons was directed in a block of ice. The induced ionization plasma was consequently probed using a radar detection set-up detecting over a wide frequency range from 200 MHz up to 2 GHz. First qualitative results of this experiment will be presented.

Coherent radio emission from the electron beam sudden appearance

We report on radio frequency measurements of the electron beam sudden appearance signal from the Telescope Array Electron Light Source (TA-ELS). The TA-ELS is constructed to calibrate the Telescope Array fluorescence telescope, and as such it can be used to mimic a cosmic-ray or neutrino induced particle cascade. This makes the TA-ELS the perfect facility to study new detection techniques such as the radio detection method. We report on the data obtained by four independent radio detection set-ups. Originally searching for either the direct Askaryan radio emission, or a radar echo from the induced plasma, all these experiments measured a very strong transient signal when the beam exits the accelerator. Due to the different scope of the individual experiments, we have detected the beam sudden appearance signal at different frequencies, ranging between 50 MHz and 12.5 GHz. The direct application in nature for this signal is found in cosmic-ray or neutrino induced particle cascades traversing through different media, such as air, ice, and rock. These measurements are compared to the theoretical predictions for this signal, where it follows that theory and experiment match very well over the full spectrum.

Constraints on the ultra-high-energy neutrino flux from Gamma-Ray bursts from a prototype station of the Askaryan radio array

Abstract We report on a search for ultra-high-energy (UHE) neutrinos from gamma-ray bursts (GRBs) in the data set collected by the Testbed station of the Askaryan Radio Array (ARA) in 2011 and 2012. From 57 selected GRBs, we observed no events that survive our cuts, which is consistent with 0.12 expected background events. Using NeuCosmA as a numerical GRB reference emission model, we estimate upper limits on the prompt UHE GRB neutrino fluence and quasi-diffuse flux from 10 7 to 10 10 GeV. This is the first limit on the prompt UHE GRB neutrino quasi-diffuse flux above 10 7 GeV.

On the feasibility of RADAR detection of high-energy cosmic neutrinos

We discuss the radar detection technique as a probe for high-energy cosmic neutrino induced particle cascades in a dense medium like ice. With the recent detection of high-energy cosmic neutrinos by the IceCube neutrino observatory the window to neutrino astronomy has been opened. We discuss a new technique to detect cosmic neutrinos at even higher energies than those covered by IceCube, but with an energy threshold below the currently operating Askaryan radio detectors. A calculation for the radar return power, as well as first experimental results will be presented.