43 research outputs found
Coherent radar reflections from an electron-beam induced particle cascade
Experiment T-576 ran at SLAC in 2018, in development of a new radar-based detection scheme for ultra-high energy neutrinos. In this experiment, the electron beam (N∼109e−
at ∼10
GeV) was directed into a plastic target to simulate a 1019
eV neutrino-induced shower in ice. This shower was interrogated with radio frequency (RF) radiation, in an attempt to measure a radar-like reflection from the ionization produced in the target during the particle shower. This technique could be employed to detect the rare interactions of ultra-high-energy neutrinos in dense material, such as polar ice sheets, extending the extant energy range of detected neutrinos up to EeV and beyond. In this proceeding, we detail the experiment and present results from the analysis and the observation of a signal consistent with a radar signal
Antarctic Surface Reflectivity Measurements from the ANITA-3 and HiCal-1 Experiments
The primary science goal of the NASA-sponsored ANITA project is measurement
of ultra-high energy neutrinos and cosmic rays, observed via radio-frequency
signals resulting from a neutrino- or cosmic ray- interaction with terrestrial
matter (atmospheric or ice molecules, e.g.). Accurate inference of the energies
of these cosmic rays requires understanding the transmission/reflection of
radio wave signals across the ice-air boundary. Satellite-based measurements of
Antarctic surface reflectivity, using a co-located transmitter and receiver,
have been performed more-or-less continuously for the last few decades.
Satellite-based reflectivity surveys, at frequencies ranging from 2--45 GHz and
at near-normal incidence, yield generally consistent reflectivity maps across
Antarctica. Using the Sun as an RF source, and the ANITA-3 balloon borne
radio-frequency antenna array as the RF receiver, we have also measured the
surface reflectivity over the interval 200-1000 MHz, at elevation angles of
12-30 degrees, finding agreement with the Fresnel equations within systematic
errors. To probe low incidence angles, inaccessible to the Antarctic Solar
technique and not probed by previous satellite surveys, a novel experimental
approach ("HiCal-1") was devised. Unlike previous measurements, HiCal-ANITA
constitute a bi-static transmitter-receiver pair separated by hundreds of
kilometers. Data taken with HiCal, between 200--600 MHz shows a significant
departure from the Fresnel equations, constant with frequency over that band,
with the deficit increasing with obliquity of incidence, which we attribute to
the combined effects of possible surface roughness, surface grain effects,
radar clutter and/or shadowing of the reflection zone due to Earth curvature
effects.Comment: updated to match publication versio
Modeling in-ice radio propagation with parabolic equation methods
We investigate the use of parabolic equation (PE) methods for solving
radio-wave propagation in polar ice. PE methods provide an approximate solution
to Maxwell's equations, in contrast to full-field solutions such as
finite-difference-time-domain (FDTD) methods, yet provide a more complete model
of propagation than simple geometric ray-tracing (RT) methods that are the
current state of the art for simulating in-ice radio detection of
neutrino-induced cascades. PE are more computationally efficient than FDTD
methods, and more flexible than RT methods, allowing for the inclusion of
diffractive effects, and modeling of propagation in regions that cannot be
modeled with geometric methods. We present a new PE approximation suited to the
in-ice case. We conclude that current ray-tracing methods may be too simplistic
in their treatment of ice properties, and their continued use could
overestimate experimental sensitivity for in-ice neutrino detection
experiments. We discuss the implications for current in-ice Askaryan-type
detectors and for the upcoming Radar Echo Telescope; two families of
experiments for which these results are most relevant. We suggest that PE
methods be investigated further for in-ice radio applications
Application of parabolic equation methods to in-ice radiowave propagation for ultra high energy neutrino detection experiments
Many ultra-high-energy neutrino-detection experiments seek radio wave signals from neutrino interactions deep within the polar ice, and an understanding of in-ice radio wave propagation is therefore of critical importance. The parabolic equation (PE) method for modeling the propagation of radio waves is a suitable intermediate between ray tracing and finite-difference time domain (FDTD) methods in terms of accuracy and computation time. The RET collaboration has developed the first modification of the PE method for use in modeling in-ice radio wave propagation for ultra high energy cosmic ray and neutrino detection experiments. In this proceeding we will detail the motivation for the development of this technique, the process by which it was modified for in-ice use, and showcase the accuracy of its results by comparing to FDTD and ray tracing