Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session B11: New Instruments and Techniques for Astrophysics |
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Sponsoring Units: DAP Chair: Dan McCammon, University of Wisconsin--Madison Room: Garden 2 |
Saturday, April 30, 2011 10:45AM - 10:57AM |
B11.00001: X-ray Polarimetry with a Negative Ion TPC Zachary Prieskorn, J. Kevin Black, Joanne Hill, Keith Jahoda, Philip Kaaret A nitromethane (CH$_{3}$NO$_{2})$ based negative ion time projection chamber (NITPC) X-ray polarimeter has been developed for measuring the polarization of energetic transients in the 2 -- 10 keV energy range. A NITPC X-ray polarimeter combines a large area detector with large modulation factors and high quantum efficiency. The primary goal is to measure the polarization of the prompt X-ray emission from gamma-ray bursts (GRBs). We detail recent improvements made to the detector design. Changes were made in the design of the GEM mounting setup, strip mounting setup, drift field cage and material selection. With a gas mixture of 197.5 Torr of CO$_{2}$ and 15 Torr of CH$_{3}$NO$_{2}$ a modulation factor of 39.3 $\pm $ 0.8{\%} was measured for 4.5 keV X-rays at the Brookhaven National Laboratory NSLS. Modulation factors at multiple energies between 3.5 and 8 keV will be reported. [Preview Abstract] |
Saturday, April 30, 2011 10:57AM - 11:09AM |
B11.00002: Simulation and Testbed Studies Aimed at Detecting Earth-Like Exoplanets with NASA's Next-Generation Space-based SIM-Lite Astrometric Observatory Benjamin Draper, Akhtar Mahmood, Bijan Nemati This research project was undertaken in conjunction with the Jet Propulsion Lab (JPL) involving a future NASA mission, called the SIM-Lite Astrometric Observatory. SIM-Lite's primary mission goal is to search for Earth-sized terrestrial planets in the habitable zone orbiting the nearby stars using astrometric techniques and to measure the precise positions of these stars to enable accurate mass determinations of the planets that orbit them with a precision equal to 1 microarcsecond. A simulation to evaluate wavefront error caused by lens aberrations in stellar interferometry was developed based on an algorithm for electron scattering proposed by D.H. Misell. This new technique could be used for any optical system to determine the distortions caused by imperfections in the lenses. We modified the Misell algorithm to evaluate the phase distortions produced by a parabolic mirror with aberrations using a HeNe Laser. The modified Misell algorithm employs Fourier transform to supply the phase information. We studied the lens aberrations and analyzed the actual data from taken from the SCDU (Spectral Calibration Development Unit) vacuum testbed at JPL. The simulation results obtained from the Misell algorithm will be presented. [Preview Abstract] |
Saturday, April 30, 2011 11:09AM - 11:21AM |
B11.00003: Status of the VERITAS gamma-ray telescope upgrade David Kieda The VERITAS gamma-ray observatory (Amado, AZ, veritas.sao.arizona.edu) is currently the world most sensitive VHE gamma-ray observatory. Key science results from the first three years of observation include the detection of VHE emission from new classes of AGN, SNR, HMXB as well as stringent upper limit on the emission of VHE gamma-rays from dark matter annihilation in Dwarf galaxies. In April 2010, VERITAS received funding to upgrade the photomultiplier tube cameras, pattern triggers, and networking systems in order to improve sensitivity and improve detector livetime. In this talk, I will describe the status of the VERITAS upgrade, and the expected improvements in sensitivity when it is completed in summer 2012. [Preview Abstract] |
Saturday, April 30, 2011 11:21AM - 11:33AM |
B11.00004: The High Altitude Water Cherenkov Instrument John Pretz The High Altitude Water Cherenkov (HAWC) experiment, under construction at Sierra Negra, Mexico, consists of a 22500 square meter area of water tanks instrumented with light-sensitive photo-multiplier tubes. The experiment detects energetic secondary particles reaching the ground when a high-energy cosmic ray or gamma ray interacts in the atmosphere above the instrument. By timing the arrival of particles on the ground, the direction of the original primary particle may be resolved with an error of between 1.0 and 0.1 degrees. Sensitive to gamma ray primaries between 50 GeV and 100 TeV, the experiment will observe Galactic sources as well as diffuse emission from the Galactic plane. The wide field of view enables long term monitoring of extra-Galactic sources and searches for flaring active galaxies and gamma ray bursts. I will describe the instrument and its anticipated sensitivity to gamma ray sources, focusing on design options to increase the effective area to gamma rays below 100 GeV. [Preview Abstract] |
Saturday, April 30, 2011 11:33AM - 11:45AM |
B11.00005: HAWC Timing Calibration Nathan Kelley-Hoskins, Petra Huentemeyer, John Matthews, Brenda Dingus The High-Altitude Water Cherenkov (HAWC) Experiment is a second-generation high sensitivity gamma-ray and cosmic-ray detector that builds on the experience and technology of the Milagro observatory. HAWC utilizes the water Cherenkov technique to measure extensive air showers. Instead of a pond filled with water (as in Milagro), an array of closely packed water tanks with 3 PMTs each is used. The cosmic ray's direction will be reconstructed using the times when the PMTs in each tank are triggered. Therefore, the timing calibration will be crucial for reaching an angular resolution as low as 0.1 degrees. We propose to use a laser calibration system, patterned after the calibration system in Milagro. The HAWC optical calibration system uses less than 1 ns laser light pulses, directed into two optical fiber networks. Each network will use optical fan-outs and switches to direct light to specific tanks. The first network is used to measure the light transit time out to each pair of tanks, and the second network sends light to each tank, calibrating each tank's 3 PMTs. Time slewing corrections will be made using neutral density filters to control the light intensity over 4 orders of magnitude. This system is envisioned to run both continuously at a low rate, or at a high rate with many intensity levels. In this presentation, we present the design of the calibration system and first measurements of its performance. [Preview Abstract] |
Saturday, April 30, 2011 11:45AM - 11:57AM |
B11.00006: The Development of Hybrid Analyses at Telescope Array Elliott Barcikowski, Monica Allen Telescope Array is the largest cosmic ray observatory in the Northern Hemisphere and is sensitive to Ultra High Energy Cosmic Rays (UHECR) with energies above $10^{18}$~eV. The flux of UHECR is too low to detect the cosmic rays directly, so UHECR observatories must rely on the extensive air shower (EAS) produced as a cosmic ray interacts in the atmosphere. Traditionally, UHECR have been detected either by using an array of Surface Detectors (SD) spread over hundreds of kilometers or by detecting photons from nitrogen fluorescence emitted as the EAS develops in the atmosphere (FD). Hybrid reconstruction incorporates both FD and SD data, giving good geometrical resolution as well as measuring the longitudinal development of the EAS produced as the primary cosmic ray propagates through the atmosphere. Hybrid reconstruction methods are presented, and development of hybrid Monte Carlo techniques are discussed. We will show that in hybrid mode the resolution of reconstructed pointing directions, the depth of shower maximum and energy are sufficient for composition studies and will allow for the calculation of a cosmic ray energy spectrum with much improved reconstruction systematics when compared to analyses using only SD or FD independently. [Preview Abstract] |
Saturday, April 30, 2011 11:57AM - 12:09PM |
B11.00007: Expansion Plans for the Telescope Array cosmic ray observatory Benjamin Stokes The Telescope Array (TA) cosmic ray observatory has now been operational for nearly three years and will be the largest cosmic ray observatory in the Northern Hemisphere for the foreseeable future. Two major expansions are currently being planned. The first expansion, TA Low Energy Extension, will increase the dynamic range of TA in order to enable seamless observation from $10^{16.5}$ to $10^{20}$~eV in primary cosmic ray energy. The second expansion, TA Next, will dramatically increase the aperture of TA above $10^{19.8}$~eV with the aim of searching for anisotropies inarrival directions for these highest energy events. Current efforts and future plans will be discussed. [Preview Abstract] |
Saturday, April 30, 2011 12:09PM - 12:21PM |
B11.00008: Detecting EHE Cosmic Rays Using Cherenkov Light Douglas Bergman Cherenkov light has been used to detect gamma rays in the TeV energy range using an imaging technique and cosmic rays in the PeV energy range using a non-imaging technique. We would like to extend the use of the non-imaging technique up to nearly 1 EeV. At these energies the technique can be used in conjunction with fluorescence detection of cosmic rays, allowing for hybrid reconstruction of shower geometries and cross calibration of energy scales. We envision using an array of Cherenkov detectors as part of the Telescope Array (TA) Low Energy extension (TALE), extending the energy range of the detector down to the Knee of the cosmic ray energy spectrum. [Preview Abstract] |
Saturday, April 30, 2011 12:21PM - 12:33PM |
B11.00009: Super atmospheric test beam for the Pierre Auger Observatory Lawrence Wiencke, Michael Coco, David Starbuck, Vincenzo Rizi, Martin Will The Pierre Auger Observatory uses the atmosphere as a giant calorimeter to measure the highest energy particles known to exist. Atmospheric clarity is the largest and most variable calibration term, especially for the highest energy air showers because they tend to land farthest from the fluorescence detectors and are consequently viewed through the most atmosphere. To refine measurements of aerosol optical depth, an R{\&}D program in south east Colorado has developed a ``super atmospheric test beam system.'' This new instrument combines a Raman LIDAR receiver with a calibrated UV laser system. This system and first comparisons between measurements of the laser light by the Raman receiver and by a simplified optical cosmic ray detector located 39 km away will be presented. This new instrument is intended for a major upgrade of the Pierre Auger Central Laser Facility in Argentina. [Preview Abstract] |
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