134 research outputs found
A First Search for Cosmogenic Neutrinos with the ARIANNA Hexagonal Radio Array
The ARIANNA experiment seeks to observe the diffuse flux of neutrinos in the
10^8 - 10^10 GeV energy range using a grid of radio detectors at the surface of
the Ross Ice Shelf of Antarctica. The detector measures the coherent Cherenkov
radiation produced at radio frequencies, from about 100 MHz to 1 GHz, by
charged particle showers generated by neutrino interactions in the ice. The
ARIANNA Hexagonal Radio Array (HRA) is being constructed as a prototype for the
full array. During the 2013-14 austral summer, three HRA stations collected
radio data which was wirelessly transmitted off site in nearly real-time. The
performance of these stations is described and a simple analysis to search for
neutrino signals is presented. The analysis employs a set of three cuts that
reject background triggers while preserving 90% of simulated cosmogenic
neutrino triggers. No neutrino candidates are found in the data and a
model-independent 90% confidence level Neyman upper limit is placed on the all
flavor neutrino+antineutrino flux in a sliding decade-wide energy bin. The
limit reaches a minimum of 1.9x10^-23 GeV^-1 cm^-2 s^-1 sr^-1 in the 10^8.5 -
10^9.5 GeV energy bin. Simulations of the performance of the full detector are
also described. The sensitivity of the full ARIANNA experiment is presented and
compared with current neutrino flux models.Comment: 22 pages, 22 figures. Published in Astroparticle Physic
Using the Hottest Particles in the Universe to Probe Icy Solar System Worlds
We present results of our Phase 1 NIAC Study to determine the feasibility of developing a competitive, low cost, low power, low mass passive instrument to measure ice depth on outer planet ice moons, such as Europa, Ganymede, Callisto, and Enceladus. Indirect measurements indicate that liquid water oceans are likely present beneath the icy shells of such moons (see e.g.,the JPL press release "The Solar System and Beyond is Awash in Water"), which has important astrobiological implications. Determining the thickness of these ice shells is challenging given spacecraft SWaP (Size, Weight and Power) resources. The current approach uses a suite of instruments, including a high power, massive ice penetrating radar. The instrument under study, called PRIDE (Passive Radio Ice Depth Experiment) exploits a remarkable confluence between methods from the high energy particle physics and the search for extraterrestrial life within the solar system. PRIDE is a passive receiver of a naturally occurring radio frequency (RF) signal generated by interactions of deep penetrating Extremely High Energy (> 10^18 eV) cosmic ray neutrinos. It could measure ice thickness directly, and at a significant savings to spacecraft resources. At RF frequencies the transparency of modeled Europan ice is up to many km, so an RF sensor in orbit can observe neutrino interactions to great depths, and thereby probe the thickness of the ice layer
Design and Performance of the ARIANNA Hexagonal Radio Array Systems
We report on the development, installation and operation of the first three
of seven stations deployed at the ARIANNA site's pilot Hexagonal Radio Array in
Antarctica. The primary goal of the ARIANNA project is to observe ultra-high
energy (>100 PeV) cosmogenic neutrino signatures using a large array of
autonomous stations each dispersed 1 km apart on the surface of the Ross Ice
Shelf. Sensing radio emissions of 100 MHz to 1 GHz, each station in the array
contains RF antennas, amplifiers, 1.92 G-sample/s, 850 MHz bandwidth signal
acquisition circuitry, pattern-matching trigger capabilities, an embedded CPU,
32 GB of solid-state data storage, and long-distance wireless and satellite
communications. Power is provided by the sun and LiFePO4 storage batteries, and
the stations consume an average of 7W of power. Operation on solar power has
resulted in >=58% per calendar-year live-time. The station's pattern-trigger
capabilities reduce the trigger rates to a few milli-Hertz with 4-sigma
thresholds while retaining good stability and high efficiency for neutrino
signals. The timing resolution of the station has been found to be 0.049 ps,
RMS, and the angular precision of event reconstructions of signals bounced off
of the sea-ice interface of the Ross Ice Shelf ranged from 0.14 to 0.17
degrees. A new fully-synchronous 2+ G-sample/s, 1.5 GHz bandwidth 4-channel
signal acquisition chip with deeper memory and flexible >600 MHz, <1 mV RMS
sensitivity triggering has been designed and incorporated into a single-board
data acquisition and control system that uses an average of only 1.7W of power.
Along with updated amplifiers, these new systems are expected to be deployed
during the 2014-2015 Austral summer to complete the Hexagonal Radio Array.Comment: 17 Page, 27 Figures, 1 Tabl
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