N2C4  Astrophysics and Space Instrumentation

Tuesday, Nov. 3  14:00-16:00  Pacific Salon 1&2

Session Chair:  Daniel Haas, SRON Netherlands Institute for Space Research, Netherlands; Peter Bloser, University of New Hampshire, United States

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(14:00) N2C4-1, The JEM-EUSO Pathfinders Status and Results

F. S. Cafagna

INFN, Bari section, Bari, Italy

On behalf of the JEM-EUSO Collaboration
The JEM-EUSO mission, on board of the International Space Station (ISS), has the primary scientific objective of doing astronomy and astrophysics detecting extreme energy cosmic rays (EECRs), above 3x10^19eV. This Extreme Universe Space Observatory (EUSO), will be the first space mission to be devoted to the study of this extreme energy range with the aim of extending the knowledge on sources, spectra and composition of cosmic rays in this energy range. This mission is a collaborative effort of about 353 Researchers of 89 Institutions, from 16 Countries. The instrument has been designed to detect the UV photons emitted in the shower produced by the EECR interaction with the atmosphere and reconstruct the arrival direction, the energy and, possibly, the nature of the EECR. This will be possible thanks to a telescope looking downward, from the ISS into the night sky, composed by an optical module that focuses the UV photons onto a focal surface, housing a matrix of multi anode photomultipliers. An infrared camera and a LIDAR will monitor the atmosphere in the telescope field of view, while an onboard and ground base systems will calibrate it. To validate this technique, the construction of three pathfinders and one precursor has been approved. EUSO-Balloon, flew on board of a stratospheric balloon, in collaboration with the French Space Agency CNES, from a Canadian Space Agency base. EUSO-TA, is taking data on ground at the Telescope Array experiment site in Utah, US. Mini-EUSO, approved by the Russian Space Agency, will be installed in the ISS. Moreover, the modified K-EUSO, using the EUSO technology, is in the stage of final definition; it will be attached at the Russian module of the ISS, as an improvement of KLYPVE experiment. Besides the actual status of the mission and precursors, details will be given on the results from the pathfinders along with plans for their consolidation and programs for other short and long duration flights.

(14:20) N2C4-2, POLAR: Gamma-Ray Burst Polarimetry on-Board the Chinese Spacelab

M. Kole

DPNC, University of Geneva, Geneva, Switzerland

On behalf of the Polar Collaboration
Polarimetry has the potential to open up a new window in the high energy astrophysics. It can be used for the study of emission processes involved in astrophysical events such as Gamma-Ray Bursts (GRBs). Despite the wealth of information which can be extracted from polarimetry measurements few have been performed successfully thus far. POLAR is a novel joint European-Chinese space-borne Compton polarimeter foreseen to be launched in 2016 on the Chinese spacelab TG-2. The instrument is designed for dedicated measurements of the hard X-ray polarisation of the prompt emission of GRBs in the energy range 50-500 keV. The polarisation degree and angle of a photon flux can be extracted by measuring the Compton scattering angles when the photons interact in a detector. The Compton scattering angles of the incoming photons are measured in POLAR using a finely segmented plastic scintillator array consisting of 1600 bars. The bars have a surface area of 6 by 6 mm and a length of 176 mm and are read out in groups of 64 by 25 flat-panel multi-anode photomultipliers. Due to its large granularity POLAR can measure the photon interaction locations, and therefore the scattering angles, with a high precision resulting in a relatively high modulation factor. The instrument furthermore has a relatively large effective area and a field of view of 1/3 of the sky thereby optimising it for studying GRBs. The instrument was shown through Geant4 simulations to be capable of performing measurements with a minimum detectable polarization below 10% for several GRBs per year. The flight model has recently been constructed and was tested extensively in recent months. The results from the instrument calibration measurements, performed using both radioactive sources and synchrotron facilities, and the results from the flight qualification tests will be presented along with the future prospects.

(14:40) N2C4-3, The Calibration of the Compton Spectrometer and Imager for the 2014 Balloon Campaign

C. A. Kierans1, S. E. Boggs1, J.-L. Chiu1, A. Lowell1, C. Sleator1, J. Tomsick1, A. Zoglauer1, M. Amman2, H.-K. Chang3, C.-H. Lin4, P. Jean5, P. von Ballmoos5, C.-Y. Yang3, C.-H. Tseng3

1Space Sciences Laboratory, UC Berkeley, Berkeley, CA, USA
2Lawrence Berkeley National Laboratory, Berkeley, CA, USA
3Institute of Astronomy, National Tsing Hua University, Hsinchu, Taiwan
4Institute of Physics, Academia Sinica, Taipei, Taiwan
5Institut de Recherche en Astrophysique et Planetologie Toulouse, Toulouse, Midi-Pyrénées, France
The Compton Spectrometer and Imager (COSI) is a balloon-borne soft gamma-ray (0.2-5 MeV) telescope designed to perform wide-field imaging, high-resolution spectroscopy, and novel polarization measurements of astrophysical sources. COSI employs a compact Compton telescope design, utilizing 12 cross-strip germanium detectors to track the trajectory of incident photons, where position and energy deposits from Compton interactions allow for a reconstruction of the source sky position, an inherent measure of the linear polarization, and significant background reduction. COSI was launched from the Long Duration Balloon site near McMurdo Station, Antarctica, in December 2014 where the primary science goal was to measure gamma-ray burst polarizations; however, the flight was cut unexpectedly short due to a leak in the balloon. We will present instrument calibrations of the energy and 3D-position of interactions within the detector that were taken in preparation for the 2014 campaign. We will discuss the integrated instrument and system testing to determine the angular resolution and detector efficiency, for comparison to simulations.

(15:00) N2C4-4, Modeling of the Probing in Situ with Neutrons and Gamma Rays (PING) Instrument Sensitivities for Planetary Landed Missions

S. F. Nowicki1, L. G. Evans2, R. D. Starr3, J. S. Schweitzer4, S. Karunatillake5, T. P. McClanahan6, J. E. Moersch7, A. M. Parsons6, C. G. Tate8

1Lujan Center, Los Alamos National Laboratory, Los Alamos, NM, USA
2Computer Sciences Corporation, Lanham-Seabrook, MD, USA
3The Catholic University of America, Washington, DC, USA
4Department of Physics, University of Connecticut, Storrs, CT, USA
5Department of Geology & Geophysics, Louisiana State University, Baton Rouge, LA, USA
6Solar System Exploration, NASA Goddard Space Flight Center, Greenbelt, MD, USA
7Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN, USA
8Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA
The Probing In situ with Neutrons and Gamma rays (PING) instrument is an innovative application of active neutron-induced gamma-ray technology. The objective of PING is to measure the elemental composition of the surface of planetary and small bodies. To study the feasibility of using PING on a planetary landed mission, we present PING’s sensitivities as a function of the composition of Martian regolith depth and PING’s uncertainties in the measurements as a function of observation time in passive and active mode. The modeled sensitivities show that in PING’s active mode, where both a Pulsed Neutron Generator (PNG) and a Gamma-Ray Spectrometer (GRS) are used, PING can interrogate the material below the rover to about 20 cm due to the penetrating nature of the high-energy neutrons and the resulting secondary gamma rays observed with the GRS. PING is capable of identifying most major and minor rock-forming elements, including H, O, Na, Mn, Mg, Al, Si, P, S, Cl, Cr, K, Ca, Ti, Fe and Th. The modeled uncertainties show that PING’s use of a PNG reduces the required observation times by an order of magnitude over a passive operating mode where the PNG is turned off and Galactic Cosmic Rays (GCR) are the excitation source. Although the uncertainties are higher in passive mode than in active mode, we show that PING can measure gamma-ray spectra in passive mode that can be used to detect changes in key marker elements and make thermal neutron measurements in about 1 minute that are sensitive to H and Cl. While the active mode allows for more complete elemental inventories with higher sensitivity, the gamma-ray signatures of some elements are strong enough to detect in passive mode.

(15:20) N2C4-5, Design of the Second-Generation ARIANNA HRA Ultra-High-Energy Neutrino Detector Systems

S. Kleinfelder

University of California, Irvine, USA

On behalf of the ARIANNA Collaboration
We report on the development of the seven station ARIANNA Hexagonal Radio Array neutrino detector systems in Antarctica. The primary goal of the ARIANNA project is to observe ultra-high energy (>100 PeV) cosmogenic neutrino signatures using a large array of autonomous stations each dispersed 1 km apart on the surface of the Ross Ice Shelf. Sensing radio emissions of 100 MHz to 1 GHz, each station in the array contains RF antennas, amplifiers, a 2 G-sample/s signal acquisition and trigger circuit I.C. (the "SST"), an embedded CPU, 32 GB of solid-state data storage, a 20 Ah LiFePO4 battery with associated battery management unit, Iridium short-burst messaging satellite and long-distance WiFi communications. The new SST chip is completely synchronous, contains 4 channels of 256 samples per channel, obtains 6 orders of magnitude sample rate range up to 2 GHz acquisition speeds. It achieves 1.5 GHz bandwidth, 12 bits RMS of dynamic range, ~1 mV RMS trigger sensitivity at >600 MHz trigger bandwidth and ps-level timing accuracy. Power is provided by the sun and LiFePO4 storage batteries, and the second-generation stations consume an average of 4W of power. The station's trigger capabilities reduce the trigger rates to a few milli-Hertz with ≤4-sigma thresholds while retaining high efficiency for neutrino signals.

(15:40) N2C4-6, Focussing Crystals for Use in Broad Band Hard X/soft Gamma-Ray Laue Lenses

E. Caroli1, E. Virgilli2, N. Auricchio1, J. B. Stephen1, F. Frontera2, A. Basili1, E. Bonnini3, E. Buffagni3, S. Del Sordo4, C. Ferrari3, P. Rosati2, S. Silvestri1

1IASF-Bologna, INAF, Bologna, Italy
2Dept. of Physics and Earth Science, University of Ferrara, Ferrara, Italy
3IMEM, CNR, Parma, Italy
4IASF-Palermo, INAF, Palermo, Italy
Hard X-/soft gamma-ray astronomy is a crucial window for the study of the most energetic and violent events in the Universe. To date the gamma- and X-ray sky has been studied extensively through imaging, spectral and timing variability analysis. However, in order to take full advantage of these results, a new generation of telescopes with a broad operational band extending from tens up to several hundreds of keV and exploiting unprecedented sensitivity (50-100 times better that current instruments) is required. We describe the results of the measurement of the focusing effect from diffractive bent crystals made of Gallium Arsenide (GaAs) that can be used successfully in the Laue configuration for the construction of high sensitivity X-/?-ray space. Laue lenses, based on diffraction from crystals in a transmission configuration, offer one possibility, albeit technically challenging, with which to fulfil these requirements and allow the construction of focusing telescopes that can extend the energy band far beyond the 80 keV limit for current multilayer concentrators. Herein, we present the results obtained from the characterization of the crystals that will be used to realise a broad band Laue demonstrator. They have been studied in terms of focusing capability and diffraction efficiency by using a flat X-ray panel imager and an HPGe spectrometer as the focal plane detectors. The GaAs tiles, bent via a surface lapping procedure, have been developed at the IMEM/CNR in Parma (Italy) in the framework of the LAUE project funded by the Italian Space Agency. The goal of this project was to build a broad band Laue lens for hard X-/soft ?-rays (80-600 keV) with unprecedented performances in terms of detection sensitivity.