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The Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER) is a radio interferometer funded by the National Science Foundation〔(【引用サイトリンク】url=http://www.nsf.gov/awardsearch/showAward?AWD_ID=1129258 )〕 to detect 21 cm Hydrogen (HI) fluctuations occurring when the first galaxies ionized intergalactic gas at around 500 Million years after the Big Bang. PAPER is a focused experiment aimed toward making the first statistical detection of the 21 cm reionization signal. Given the stringent dynamic range requirements for detecting reionization in the face of foregrounds that are five orders of magnitude brighter, the PAPER project is taking a carefully staged engineering approach, optimizing each component in the array to mitigate, at the outset, any potentially debilitating problems in subsequent data calibration and analysis. This staged approach addresses the observational challenges that arise from very-wide-field, high-dynamic-range imaging over wide bandwidths in the presence of transient terrestrial interference. PAPER began as a collaboration between Don Backer of the UC Berkeley Radio Astronomy Laboratory and Richard Bradley of the National Radio Astronomy Observatory. With Backer's passing in 2010, Aaron Parsons has assumed leadership of PAPER on the side of UC Berkeley. The two fundamental concerns that most influence the design of any HI reionization detection instrument are removing foregrounds and achieving the requisite sensitivity. The PAPER approach heavily emphasizes the former; the level of instrumental calibration and foreground characterization that will be required to model and remove polarized galactic synchrotron emission, continuum point-sources, and galactic/extra-galactic free-free emission is unprecedented in the 100-200 MHz band expected to encompass reionization. PAPER consists of two distinct arrays: one located at the NRAO site in Green Bank, WV, which is used primarily for engineering investigations and field testing, and another located at the South African SKA site in the Karoo desert of the Northern Cape, South Africa.,〔(【引用サイトリンク】url=http://www.ska.ac.za/newsletter/issues/15/05.php )〕 which is used for science observations. ==PAPER in Green Bank, West Virginia, USA== PAPER in Green Bank has evolved over a few years from exploring basic systematics in a rudimentary four-element array to the more comprehensive system performance testing with the thirty-two element array that is currently deployed there. PAPER activities at the NRAO site near Green Bank, WV began in 2005 with the deployment of a 4-antenna, single-polarization interferometer. After substantial testing and improvement of the PAPER design, we deployed eight antennas in a nearby field in April, 2008. This new system incorporated antenna elements with ground-screen flaps and a digital correlator based on CASPER hardware. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Precision Array for Probing the Epoch of Reionization」の詳細全文を読む スポンサード リンク
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