Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session T18: Particle AstrophysicsLive
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Sponsoring Units: DPF Chair: Frank Schroeder, University of Delaware |
Monday, April 19, 2021 3:45PM - 3:57PM Live |
T18.00001: Evolution of primordial neutrino helicities in astrophysical magnetic fields Gordon Baym, Jen-Chieh Peng Primordial neutrinos decoupled in the early universe predominantly in helicity eigenstates. Their subsequent propagation through the residual cosmic and galactic magnetic fields partially flips their helicities.\footnote{G. Baym and J.-C. Peng, arXiv:2012.12421 [hep-ph].} In view of the report of a possible large effective magnetic moment for solar neutrinos from the XENON1T experiment, we estimate the magnitudes of the helicity flips for primordial Dirac neutrinos both in galactic and cosmic magnetic fields. Majorana neutrinos would not undergo such flips. The helicity flip probability is sensitive not only to the magnetic moment of neutrinos but also to the properties of galactic and cosmic fields, and thus can thus potentially probe astrophysical magnetic fields. We find that even a moment several orders of magnitude smaller than that possibly found by XENON1T could lead to significant helicity changes of Dirac neutrinos as they propagate to detectors on Earth. [Preview Abstract] |
Monday, April 19, 2021 3:57PM - 4:09PM Live |
T18.00002: Implications of helicity modifications of primordial neutrinos on their detection Jen-Chieh Peng, Gordon Baym Detection of relic neutrinos from the Big Bang, e.g., through the inverse tritium beta decay reaction (ITBD) in the PTOLEMY experiment, remains a major challenge. While the ITBD rate is insensitive to the helicity of Majorana neutrinos, helicity flips of Dirac neutrinos both via interactions with gravitational perturbations and cosmic and galactic magnetic fields does effect the ITBD detection rate for neutrino masses below\footnote{G. Baym and J.-C. Peng, arXiv:2012.12421 [hep-ph].} $\sim 10^{-2}$ eV. However, resolving relic neutrino events from the tritium beta decay background becomes increasingly difficult with lower neutrino mass, and will require advances in electron detection techniques. We also discuss the prospect of detecting the ITBD reaction for the first time using an intense $^{51}$Cr neutrino source. [Preview Abstract] |
Monday, April 19, 2021 4:09PM - 4:21PM Live |
T18.00003: The Radar Echo Telescope for Cosmic Rays Rose Stanley We present the Radar Echo Telescope for Cosmic Rays (RET-CR). Radar detection of in-ice particle cascades is of great interest for its application to explore the as yet undetected $>$10 PeV cosmic-neutrino flux. The RET-CR detector aims to show the in-situ proof-of-principle of the method by detecting the in-ice continuation of a cosmic-ray-induced particle cascade impinging on a high-elevation ice sheet. We present the foreseen RET-CR detector layout and sensitivity obtained from the RET-CR simulation framework. This framework combines a full Monte-Carlo simulation of the in-air propagation of the cosmic-ray-induced particle cascade, its detection by the surface set-up, its continuation into the ice, and its detection by the radar set-up. [Preview Abstract] |
Monday, April 19, 2021 4:21PM - 4:33PM Live |
T18.00004: The UHE-Neutrino Observatory Trinity Nepomuk Otte The detection of TeV-PeV neutrinos with IceCube has cracked open a new window in astrophysics. The revelation of a relatively hard spectrum and the unknown origin of the neutrino flux are strong motivations to extend neutrino measurements to even higher energies, namely the ultrahigh-energy (UHE) regime above 10 PeV. In this talk, I show that a system of air-shower imaging telescopes is a viable UHE neutrino detector. Based on detailed design considerations, I present Trinity, a system ofsix Cherenkov telescopes. I discuss the system's sensitivity, how it can be built, address operational constraints, and plans to test the concept. [Preview Abstract] |
Monday, April 19, 2021 4:33PM - 4:45PM Live |
T18.00005: Simulation of In-Ice Radio Propagation with Parabolic Equation Methods Steven Prohira Parabolic equation (PE) methods have been used for decades to study the propagation of radio frequency (RF) waves in the atmosphere, and acoustic waves under the sea. They are approximate numerical solutions to Maxwell's equations that, under certain criteria, offer accurate results at a fraction of the computational cost of more exact numerical solution methods (finite-difference time-domain, FDTD). We present a first application of PE to the problem of in-ice radiowave propagation, of critical importance to radio-based detection of ultra high energy (UHE) neutrinos. We find that PE methods are a useful tool for accurate simulation of long baseline in-ice radio propagation for two reasons: 1) they give consistent results with FDTD at a fraction of the computational cost, and 2) they model propagation effects that are not currently accounted for in widely used in-ice radio simulation codes. We present implications for current and future experiments, including the Radar Echo Telescope, an under-development, next-generation UHE neutrino observatory. [Preview Abstract] |
Monday, April 19, 2021 4:45PM - 4:57PM Live |
T18.00006: Radio Wave Propagation in Depth-Dependent Anisotropic Media, With Application to Neutrino Vertex Reconstruction Nicholas Harty, David Seckel High energy neutrinos interact with glacial ice at the South pole. These interactions produce radio frequency emissions through the Askaryan effect. The Askaryan Radio Array (ARA) studies these emissions using radio antennas placed in the ice to reconstruct individual neutrino events. The second generation IceCube (IceCube Gen-2), includes plans for an array of radio stations to enhance sensitivity at the highest neutrino energies. Past studies have suggested glacial ice sheets behave as a biaxial, depth dependent medium. Here we develop a theoretical model for radio-frequency electromagnetic propagation in South Pole ice using coupled ordinary differential equations (ODEs). We then test this model against experimental radio sounding data, using several different index of refraction profiles. Lastly, we implement a Python package to deal with general anisotropic, depth-dependent radio propagation into NuRadioMC, a monte carlo simulation package used to simulate neutrino interactions. [Preview Abstract] |
Monday, April 19, 2021 4:57PM - 5:09PM Live |
T18.00007: Searching for High Energy Neutrinos with the Askaryan Radio Array Brian Clark The Askaryan Radio Array (ARA) is an experiment deployed at the South Pole to search for ultra-high energy ($>10$ PeV) neutrinos. ARA searches for neutrinos by burying clusters of antennas deep (200m) in the glacial ice, and looking for the radio emission produced by neutrino-nucleon interactions. In this talk, I will summarize the status of the experiment. I will discuss the latest results in the ARA search for neutrinos, which produced the best limit from an in-ice radio array above 100 PeV. I will also highlight ongoing work in analysis and reconstruction, and their implications for the design of next generation experiments. [Preview Abstract] |
Monday, April 19, 2021 5:09PM - 5:21PM Live |
T18.00008: Reconstruction of UHE neutrinos with the Askaryan Radio Array (ARA) experiment Jorge Torres Searching for ultra-high energy (UHE) neutrinos ($E_\nu>100$ PeV), ARA is an experiment located at the South Pole consisting of five clusters of antennas buried at $\sim$200 m in the ice. These antennas are designed to detect radiation emitted by relativistic particle showers that are byproducts of UHE neutrino interactions with ice. In this talk, I will discuss work on reconstructing the properties of signals observed from these neutrino interactions such as signal polarization, deposited energy, and neutrino direction. I will also comment on how this will improve the sensitivity of future point-source neutrino searches with ARA. [Preview Abstract] |
Monday, April 19, 2021 5:21PM - 5:33PM Live |
T18.00009: Improving Analysis Efficiency with a Phased Array Trigger as Part of the Askaryan Radio Array Kaeli Hughes The Askaryan Radio Array (ARA) at the South Pole is designed to detect the radio emission induced by ultra-high-energy cosmic neutrinos that interact within the ice. ARA consists of five independent stations, including one station equipped with an extra string of antennas as well as a phased array trigger. This trigger design adds signals together in sets of predetermined time delays before triggering, with each set of time delays corresponding to a specific direction. Because signals add coherently, while noise largely does not, this effectively lowers the trigger threshold compared to the other ARA stations. In this talk, I will present work on the latest ARA analysis, which uses one year of data from this newest station, and show how the improvements at low thresholds at the trigger level can lead to improved analysis efficiency for weaker signals and lower energies. [Preview Abstract] |
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