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 L10: Cosmic Ray Spectrum and CompositionLive
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Sponsoring Units: DAP Chair: Dave Kieda, Univ. Utah |
Sunday, April 18, 2021 3:45PM - 3:57PM Live |
L10.00001: Deployment of an Auger micro-array within Telescope Array for cross-calibration studies (Auger@TA – phase II) Frederic Sarazin Auger@TA is a joint working group of the Telescope Array (TA) and the Pierre Auger Observatory (Auger), the two leading Ultra-High Energy Cosmic-Ray (UHECR) experiments located respectively in the northern and southern hemispheres. The aim of the program is to achieve a cross-calibration of the Surface Detector (SD) from both experiments. The Auger and TA SD stations are based on different detection media and respond differently to the electromagnetic and muonic components of the shower. In the first phase of the effort, we performed a comparative response study using a pair of co-located Auger and TA SD stations deployed within TA for a small collection of showers. In this presentation, we will focus on our plan for the second phase of Auger@TA, which consists in deploying an independently-operated Auger hexagon (7 stations) inside TA to perform event-level comparisons for relatively low-energy UHECR showers. [Preview Abstract] |
Sunday, April 18, 2021 3:57PM - 4:09PM Live |
L10.00002: Performance of the Cosmic Ray Energetics and Mass Instrument for the International Space Station (ISS-CREAM) Kenichi Sakai, Jason Link, Tyler Anderson, Yu Chen, Stephanie Coutu, Tyler LaBree, John Mitchell, Isaac Mognet, Scott Nutter, Jacob Smith, Monong Yu The Cosmic Ray Energetics and Mass Instrument for the International Space Station (ISS-CREAM) was built by an international collaboration from the US, Republic of Korea, France, and Mexico. The scientific objective of the program is to measure the elemental spectra of cosmic rays from Z=1 to Z=26 over the energy range of 10$^{12}$-10$^{15}$ eV. The instrument was installed on the international space station on August 22, 2017 with operations terminated on February 12, 2019 resulting in approximately 1.5 years of operation. In this talk, we discuss the performance of the instrument and detectors during its period of operation. We will compare GEANT-4 simulations to instrument data, demonstrate how we determine the appropriate energy scale for the instrument, and show some preliminary results. [Preview Abstract] |
Sunday, April 18, 2021 4:09PM - 4:21PM Live |
L10.00003: Radio Detection of Cosmic-Ray Air Showers at the Pierre Auger Observatory Frank Schroeder The Pierre Auger Observatory in Argentina features the world-largest array of surface detectors for ultra-high-energy cosmic rays. It consists of 1660 water-Cherenkov detectors spread with 1.5 km spacing over an area of 3000 km$^2$ for the detection of cosmic-ray air showers. As part of the AugerPrime upgrade, a scintillation panel and a radio antenna will enhance each of these surface detectors in order to increase the sensitivity to the mass of the primary cosmic-ray nuclei initiating the showers. Together with the muon measurements provided by the water-Cherenkov detectors, the antennas will enable a per-event discrimination of showers initiated by heavy and light nuclei and further tests of hadronic interactions models for very inclined air showers. The design builds on the expertise with the Auger Engineering Radio Array (AERA) covering 17 km$^2$ with about 150 antenna stations. The SALLA antenna used for the upgrade has been successfully tested in prototype stations in AERA as well as in the Tunka-Rex experiment. Among the many achievements of AERA is the demonstration of an accurate calorimetric measurement of the shower energy and of the feasibility to detect very inclined air showers. [Preview Abstract] |
Sunday, April 18, 2021 4:21PM - 4:33PM Live |
L10.00004: IceAct an Imaging Air Cherenkov Telescope upgrade for the IceCube Neutrino Observatory Larissa Paul, Matthias Plum, Karen Andeen IceAct is a proposed array of small and cost effective Imaging Air Cherenkov Telescopes situated at the IceCube Observatory at the South Pole. A single Imaging Air Cherenkov Telescope is capable of measuring the whole electromagnetic component of an air shower by measuring the Cherenkov light emitted within the atmosphere. This gives IceAct the unique opportunity to complement the coincident detection of air showers already capable with the IceCube Neutrino Observatory. Currently the electromagnetic footprint is measured by the surface array, IceTop, in coincidence with the high energetic muonic component measured by the in-ice detector, IceCube. Since January 2019, two prototype IceAct telescopes with 61 SiPM pixels apiece are taking data during the austral winter. These two telescopes provide the opportunity to study detector performance of Imaging Air Cherenkov Telescopes in the harsh conditions at the South Pole, and to study hybrid events with the existing detector components. We will present the current status and the future plans for this novel detector component. [Preview Abstract] |
Sunday, April 18, 2021 4:33PM - 4:45PM Live |
L10.00005: Overview of CALET Results from Five Years of Observations on the ISS Nicholas Cannady The Calorimetric Electron Telescope (CALET) is a high-energy cosmic ray and gamma ray detector on the International Space Station. CALET was launched in August 2015 and installed on the Japanese Experiment Module Exposed Facility and has continued stable data acquisition since soon thereafter. The main instrument is an electromagnetic calorimeter with normal-incidence depth of 30 radiation lengths, comprising a plastic scintillating paddle charge detector, an alternating plastic scintillating fiber-tungsten sheet imaging calorimeter, and a lead tungstate total absorption calorimeter. The calorimeter is sensitive to cosmic-ray electrons (and positrons) and gamma rays from 1 GeV to beyond 10 TeV and cosmic-ray hadrons up to PeV total energies. Using data obtained over 5 years of operation, we will briefly summarize results from CALET observations, including the all-electron (electron$+$positron) energy spectrum, energy spectra of cosmic-ray nuclei, abundances of ultra-heavy cosmic-ray nuclei, and observations of transient and persistent sources of gamma rays. [Preview Abstract] |
Sunday, April 18, 2021 4:45PM - 4:57PM Live |
L10.00006: CALET Ultra-Heavy Cosmic-Ray Analysis Wolfgang Zober, Brian Rauch, Nicholas Cannady, Anthony Ficklin The Calorimetric Electron Telescope (CALET), launched to the ISS in August 2015, utilizes its main calorimeter charge detector to measure CR nuclei from $_{1}$H to $_{40}$Zr. In order to maximize the acceptance of the rare ultra-heavy (UH) CR above $_{30}$Zn, a special high duty cycle ($\sim90\%$) UH trigger is used that does not require passage through the 27 radiation length deep total absorption calorimeter. This provides a $\sim6\times$ increase in geometry factor, although reduced by ISS obstructions, allowing CALET to collect in 5 years a UHCR data set with statistics comparable to those from the first flight of the balloon-borne SuperTIGER instrument but without the need for atmospheric corrections. Previous CALET UHCR analyses using time and position corrections based on $_{26}$Fe and a geomagnetic vertical cutoff rigidity selection have shown abundances of even nuclei in agreement with SuperTIGER. To further improve resolution and maximize statistics a trajectory dependent geomagnetic rigidity selection is employed here as well as a novel independent analysis with L-shells. We present new results from the extended analysis of the UH spectra measured by CALET. [Preview Abstract] |
Sunday, April 18, 2021 4:57PM - 5:09PM Live |
L10.00007: The Surface Enhancement of IceCube Alan Coleman IceTop is a cosmic ray (CR) air shower detector, located at the South Pole, and is part of the IceCube Neutrino Observatory. The current array consists of ice-Cherenkov tanks and covers roughly 1 km$^2$. Currently, IceTop is undergoing an enhancement to include new detector types, scintillator panels and radio antennas. This addition will increase the science capabilities of the IceCube surface array. The scintillator panels will allow for the calibration of the snow overburden on the tanks. The accumulation of snow is a source of systematic uncertainty and reduces the detection efficiency of CRs with energies below $\sim$1 PeV. The new array will be sensitive to CR primaries above a few hundred TeV, extending the energy range of the Observatory. With the observation of Xmax by the antennas and the additional information from the scintillators, the multi-detector method will also improve the energy resolution and the CR-mass discrimination, a requirement for the field to make significant progress. I will present the first results from the prototype station and the plans and outlook for the full-scale array. [Preview Abstract] |
Sunday, April 18, 2021 5:09PM - 5:21PM Live |
L10.00008: Reconstruction of Nearly Horizontal Muons in the HAWC Observatory Robert Wayne Springer A Hough transform algorithm is used to identify muons traversing the HAWC observatory by finding a line in the 3d point cloud of PMT hits (x\textunderscore i,y\textunderscore i, and ct\textunderscore i). The arrival direction of the muon can be estimated from this line. Background Extensive Air Shower (EAS) fragments are identified by the presence of a lateral extension of PMT hits in a plane normal to the muon candidate trajectory. A geometry-based simulation has been developed to improve and estimate arrival direction reconstruction resolution and effective area. HAWC is surrounded by volcanoes that provide a variation of material depths from open sky to over 15 km of rock, thereby providing a means to measure muon flux as a function of material depth. A description of the reconstruction techniques and estimates of detector resolution, backgrounds, and effective area as a function of arrival direction, will be provided. [Preview Abstract] |
Sunday, April 18, 2021 5:21PM - 5:33PM Live |
L10.00009: Geomagnetic and Askaryan Contributions to the Radio Emission from Cosmic-Ray Air Showers at the South Pole Ek Narayan Paudel, Frank Schroeder Ultra-high energy cosmic rays are emitted by yet unknown extreme astrophysical sources in the Universe. Due to their very low flux, such cosmic rays can only be studied indirectly using extensive air showers generated by them in the Earth’s atmosphere. Among several techniques, radio antennas can measure the radio emission from these showers which can be utilized for the reconstruction of the mass, energy, and arrival direction of the cosmic rays. Geomagnetic emission is the dominant mechanism of radio emission from air showers. It occurs due to a time-dependent transverse current in the shower front which is caused by the charge separation of air shower particles in the Earth’s magnetic field. Geomagnetic emission is linearly polarized along the direction of the geomagnetic Lorentz force. The less dominant Askaryan emission occurs due to time-dependent negative charge excess developed at the shower front and is radially polarized. CORSIKA/CoREAS air-shower simulations were used to simulate the radio emission from air showers at the location of the South Pole. In this talk, we are presenting our study on the relative fraction of the Askaryan contribution in the radio emission of these air showers and its dependence on parameters such as the arrival direction. [Preview Abstract] |
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