Session G8: Cosmogenic and Astrophysical Neutrinos

Observation of PeV Neutrinos in IceCube

Neutrinos provide a unique window into cosmic-ray acceleration processes: they are produced almost exclusively in hadronic interactions and travel without absorption or deflection from their place of production. This talk will discuss the recent observation by IceCube of neutrinos at energies above 1 PeV, somewhat above what is expected from atmospheric neutrino backgrounds, as well as prospects for future searches and studies of additional lower-energy data (100 TeV) to determine whether they are of astrophysical or atmospheric origin.   

Point source searches with the IceCube Neutrino Observatory

Observing a point source of astrophysical neutrinos would be a ``smoking gun'' signature of a cosmic ray accelerator. Here we discuss past and future searches for point sources using IceCube, a cubic kilometer Cherenkov detector at the South Pole. Results from three years of partial-detector data will be shown. I will then describe how upcoming analyses will improve IceCube's sensitivity to point sources by including two years of full-detector data and incorporating new event reconstruction techniques.   

Recent IceCube Results for Diffuse Neutrinos and Future Outlook

The IceCube Neutrino Observatory has recently seen high energy neutrino events not consistent with conventional atmospheric neutrino predictions and which may derive from a prompt atmospheric component or from astrophysical sources (although they appear unconnected to a GZK spectrum). In this talk I will discuss how these results may be extended with newly available data from the detector in both its complete and almost complete configurations to better evaluate the key spectral region of muon neutrinos around 100 TeV.   

Performance study of Cascade Reconstruction at the Glashow Resonance in IceCube

The IceCube observatory is a $1\,\mbox{km}^3$ neutrino detector located at the South Pole. Of particular interest are electromagnetic and/or hadronic particle showers (cascades) induced by electron anti-neutrinos that scatter of atomic electrons in ice, the so-called Glashow Resonance, i.e. $W^-$ production at $E_\nu=6.3\,\mbox{PeV}$. We present performance studies of likelihood based cascade reconstruction algorithms using Monte Carlo simulations and demonstrate IceCube's capabilities to reconstruct position, direction and the energy of cascades from the in-situ laser light sources in this energy regime.   

Overview of newly installed surface antennas in the Askaryan Radio Array

The Askaryan Radio Array (ARA) located at the South Pole is in a period of expansion. This season eight surface antennas located at two sites were added to the existing array. These surface antennas are copper dipole antennas with nominal frequency response from 30-1000 MHz that will be sensitive to Askaryan effect neutrino signals as well as cosmic ray produced extensive air shower signals and will allow for coincident detection with in-ice antenna channels. A review of these surface antennas will be presented.   

Monte Carlo studies of ARA detector optimization

The Askaryan Radio Array (ARA) is a neutrino detector deployed in the Antarctic ice sheet near the South Pole. The array is designed to detect ultra high energy neutrinos in the range of 0.1-10 EeV. Detector optimization is studied using Monte Carlo simulations.   

ARA TestBed background data analysis and neutrino sensitivity limit study.

Askaryan Radio Array (ARA) is a ultra-high energy (UHE) cosmic neutrino detector located at the south pole. The cosmic ray flux cut off above primary energies of $10^{19.5}$eV lead us to expect an UHE neutrino flux due to the GZK effect. The detection of these UHE cosmic neutrinos will add to the understanding of the sources and physics of UHE cosmic rays. The radio Cherenkov technique is one of the most promising technologies for the detection of UHE cosmic neutrinos. ARA uses the radio Cherenkov technique by deploying radio frequency antennas at 200m depth in the Antarctic ice. A prototype ARA TestBed station was deployed in the 2010-2011 season and the first ARA station was deployed in the 2011-2012 and 2012-2013 seasons. We present the results of the first neutrino search with ARA, using data taken from 2011-2012 with the ARA TestBed.   

Trigger developments for ARA

The Askaryan Radio Array (ARA) is a planned large-scale neutrino detector at the South Pole aiming at observing ultra-high-energy cosmogenic neutrinos via detecting radio Cherenkov radiation from neutrinos' interaction with Antarctic ice. By the end of the austral summer of 2012/13 three detector stations have been deployed at depths of up to 200 m. A prototype detector station has been taking data for two years. The final array is planned to consist of 37 stations with a 200 km$^{2}$ coverage, and provide high sensitivity in the range of 10 PeV to 10 EeV. In order to increase the discover potential of the stations, advanced triggering schemes are in development which take into account the topology of signal events. Here a brief status and the triggering schemes in development will be presented, and based on simulations their improvements to ARA neutrino sensitivity will be discussed.   

Performance and Status of the ARIANNA Experiment for Detection of GZK Neutrinos

Dedicated high-energy neutrino telescopes based on optical Cherenkov techniques have been scanning the cosmos for about a decade. Consequently, neutrino flux limits have improved by several orders of magnitude in the TeV-PeV energy interval. At higher energies, detectors using radio Cherenkov techniques have produced aggressive limits on the neutrino flux. An experiment called ARIANNA is a novel concept for the next generation of astrophysical neutrino detection, which takes advantage of unique geophysical features of the Ross Ice Shelf in Antarctica will be described. Utilizing the radio Cherenkov technique, ARIANNA is designed to improve sensitivity to neutrinos with energies in excess of 100 TeV by at least a factor of 10 relative to current limits. It consists of a scalable array of autonomous stations with an inner-station spacing of 1 kilometer. The physics motivation for ARIANNA, which includes a measurement of the GZK neutrino flux, whose existence is relatively secure but frustratingly small, and the search for nonstandard particle physics will be presented. The progress toward completion of the hexagonal radio array, initial analysis results and performance of three new stations deployed in December of 2012 will be reported.