Bulletin of the American Physical Society
APS April Meeting 2017
Volume 62, Number 1
Saturday–Tuesday, January 28–31, 2017; Washington, DC
Session H4: Cosmic-rays: Anisotropy and Ground Based Observations |
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Sponsoring Units: DAP Chair: Amy Connolly, The Ohio State University Room: Virginia A |
Sunday, January 29, 2017 8:30AM - 8:42AM |
H4.00001: A Search for Cosmic-ray Proton Anisotropies with Fermi LAT Matthew Meehan, Justin Vandenbroucke In eight years of operation, the Fermi Large Area Telescope (LAT) has detected a large sample of cosmic-ray protons. The LAT's wide field of view and full-sky coverage make it an excellent instrument for studying anisotropies in the arrival directions of protons at all angular scales. These capabilities enable the LAT to make a full-sky 2D measurement of cosmic-ray proton anisotropy complementary to many recent TeV measurements, which are performed by projecting onto right ascension. Any detected anisotropies probe the structure of the local interstellar magnetic field and could indicate the presence of a nearby source [Preview Abstract] |
Sunday, January 29, 2017 8:42AM - 8:54AM |
H4.00002: Systematic Study of the Time-Dependence of the Sidereal Cosmic-Ray Anisotropy and Solar Dipole with IceCube Michael Lukasik Between 2009 and 2016, the IceCube Detector located deep within the ice at the South Pole has detected nearly 380 billion cosmic rays. The large statistics of the data set allows us to observe the large- and small-scale anisotropy in their arrival direction distribution and the solar dipole caused by the orbital motion of the Earth. In this talk, we present a detailed systematic study of the sidereal anisotropy and the solar dipole. In particular, we search for a possible seasonal modulation in amplitude. Any statistically significant seasonal variation of the amplitude over the course of one orbital rotation could indicate the presence of a directional dependence, for example the Compton-Getting effect. To study the time dependence, the effect of the sidereal anisotropy on the solar dipole and vice versa need to be carefully studied and simulated. [Preview Abstract] |
Sunday, January 29, 2017 8:54AM - 9:06AM |
H4.00003: Analysis of Near Horizontal Muons at HAWC Ahron Barber The HAWC (High Altitude Water Cherenkov) gamma ray observatory observes muons with nearly horizontal trajectories. HAWC is located at an altitude of 4100 meters a.s.l. on Sierra Negra in Mexico. The Gamma and Cosmic Ray detector is composed of 300 water tanks, 7.3 m in diameter and 4.5 m tall, spread over a physical area of 22,000 m2. Due to its thickness of 4.5 m, HAWC acts as a hodoscope capable of observing muons with trajectories at zenith angles greater than 75 degrees to just over 90 degrees. These muon trajectories have a unique signal in that they are linear and travel at nearly the speed of light. CORSIKA simulations indicate that these muons originate from high zenith angle cosmic ray events, where the air shower core is located at great distance from HAWC. I will present the angular distribution and rate at which HAWC observes these muon events. [Preview Abstract] |
Sunday, January 29, 2017 9:06AM - 9:18AM |
H4.00004: Using GALPROP to Study H and He Spectra Hardening in Cosmic-Ray Data Yuxi Lu, Mathew Chung, Xinying Ding, Nicolas Picot-Clemente, Eun-Suk Seo Recent measurements from CREAM, then PAMELA and AMS-02, showed a hardening in cosmic-ray spectra at high energies. GALPROP is a numerical code that calculates cosmic-ray propagation in the Galaxy. Using GALPROP, we added rigidity breaks in cosmic-ray diffusion and source spectra to reproduce the latest data. We present results of this study and give ranges of parameter values that are allowed with current measurements. [Preview Abstract] |
Sunday, January 29, 2017 9:18AM - 9:30AM |
H4.00005: Field Testing the EUSO-SPB instrument Johannes Eser, Austin Cummings, Rachel Gregg, Harry Krantz, Zach Polonsky, Lawrence Wiencke In September of 2016 the the Extreme Universe Space Observatory on a super pressure balloon (EUSO-SPB) instrument was tested in the west Utah desert with a laser "test beam" system. Laser tracks were measured at distances of 24 km with the laser tilted away from the detector. This geometry is similar to the expected geometry of downward going cosmic ray air showers during the planned balloon flight. We describe the test beam system and the tests. [Preview Abstract] |
Sunday, January 29, 2017 9:30AM - 9:42AM |
H4.00006: The Non-Imaging CHErenkov (NICHE) Array: A TA/TALE extension using Cherenkov radiation to measure Cosmic Ray Composition to sub-PeV energies John Krizmanic, Douglas Bergman, Yoshiki Tsunesada, Tareq Abu-Zayyad, John Belz, Gordon Thomson Co-sited with the Telescope Array (TA) Low Energy (TALE) extension, the Non-Imaging CHErenkov (NICHE) Array will measure the flux and nuclear composition evolution of cosmic rays (CRs) from below 1 PeV to 1 EeV in its eventual full deployment. NICHE will co-measure CR air showers with TA/TALE and will initially be deployed to observe events simultaneously with the TALE telescopes acting in imaging-Cherenkov mode, providing the first hybrid-Cherenkov (simultaneous imaging and non-imaging Cherenkov) measurements of CRs in the Knee region of the CR energy spectrum. NICHE uses easily deployable detectors to measure the amplitude and time-spread of the air-shower Cherenkov signal to achieve an event-by-event measurement of X$_{\rm max}$ and energy, each with excellent resolution. First generation detectors are under construction and will form an initial prototype array (jNICHE) that will be deployed in early 2017 at the TA/TALE site. In this talk, the NICHE design, array performance, jNICHE development, and status will be discussed as well as NICHE's ability to measure the cosmic ray nuclear composition as a function of energy. [Preview Abstract] |
Sunday, January 29, 2017 9:42AM - 9:54AM |
H4.00007: Safely Transporting the assembled EUSO-SPB instrument 1000 miles for field testing Austin Cummings, Rachael Gregg, Zach Polonsky The EUSO-SPB instrument assembled and tested at Colorado School of Mines and then transported in this state to the Telescope Array site in Delta Utah for field tests. 6 hours after arrival the instrument recorded first light from a laser 20 km distant. We describe the structures and methods that we developed drive this instrument to the test site. The vibration data collected during the 1000 mile round trip and the lessons learned will also be presented. In our experience, there is relatively little quantitative information available about this type of critical operation. [Preview Abstract] |
Sunday, January 29, 2017 9:54AM - 10:06AM |
H4.00008: Monitoring the TeV sky on short timescales with HAWC Israel Martinez-Castellanos The High-Altitude Water Cherenkov is a large field of view ($\sim$2sr) observatory sensitive to very-high energy gamma rays ($\sim$0.5-100TeV). It is located in central Mexico ($\sim$19$^\circ$N) and has a high duty cycle ($>$95\%). These characteristics allow it to continuously survey the northern sky, looking for flares, bursts and possibly other unknown transient phenomena. Presented here is an unbiased search on the order of hours and performed online, which allow us to provide alerts and useful information to other experiments. In particular, it can trigger follow-ups from small FOV instruments, enabling deep observations of sources during their high state activity in the TeV range, which are valuable measurements than can constrain acceleration mechanisms. [Preview Abstract] |
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