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Radar Sensing of Ultra-High Energy Cosmic Ray Showers
J. P. Lundquist, diplomsko delo

Opis: The intent of this paper is to review the history and potential importance of the use of radar techniques in detecting the ionization columns of ultra-high energy cosmic ray showers and give a short overview of a currently planned radar experiment at the Telescope Array. There is much activity in cosmic ray research to study the composition and source locations of this phenomena. Radar would be an important addition to fluorescence and scintillation detection as it theoretically could attain greater volume coverage and nearly the accuracy of fluorescence systems with less infrastructure and much longer running times. The currently estimated mean echo lifetime is on the order of 50 µs for a cosmic ray of energy 10^19 eV. It is shown that a continuous wave bi-directional radar system transmitting in the low-VHF with a large obstruction between receiver and transmitter (such as a mountain or earth curvature), which assures direct transmission is reduced, is the nominal configuration and the planned radar experiment at the Telescope Array satisfies these requirements.
Najdeno v: ključnih besedah
Ključne besede: cosmic rays, radar
Objavljeno: 24.04.2020; Ogledov: 1574; Prenosov: 0
.pdf Polno besedilo (4,71 MB)

First upper limits on the radar cross section of cosmic-ray induced extensive air showers
J. P. Lundquist, R.U. Abbasi, 2017, izvirni znanstveni članek

Opis: TARA (Telescope Array Radar) is a cosmic ray radar detection experiment colocated with Telescope Array, the conventional surface scintillation detector (SD) and fluorescence telescope detector (FD) near Delta, Utah, U.S.A. The TARA detector combines a 40 kW, 54.1 MHz VHF transmitter and high-gain transmitting antenna which broadcasts the radar carrier over the SD array and within the FD field of view, towards a 250 MS/s DAQ receiver. TARA has been collecting data since 2013 with the primary goal of observing the radar signatures of extensive air showers (EAS). Simulations indicate that echoes are expected to be short in duration (∼ 10 µs) and exhibit rapidly changing frequency, with rates on the order 1 MHz/µs. The EAS radar cross-section (RCS) is currently unknown although it is the subject of over 70 years of speculation. A novel signal search technique is described in which the expected radar echo of a particular air shower is used as a matched filter template and compared to waveforms obtained by triggering the radar DAQ using the Telescope Array fluorescence detector. No evidence for the scattering of radio frequency radiation by EAS is obtained to date. We report the first quantitative RCS upper limits using EAS that triggered the Telescope Array Fluorescence Detector.
Najdeno v: ključnih besedah
Ključne besede: Cosmic ray, Radar, Digital signal processing, Radar cross-section
Objavljeno: 27.04.2020; Ogledov: 1373; Prenosov: 0
.pdf Polno besedilo (6,16 MB)

TARA: Forward-scattered radar detection of UHECR at the telescope array
J. P. Lundquist, J. Belz, 2013, objavljeni znanstveni prispevek na konferenci

Opis: Increased event statistics will be required to definitively answer the question of the origin(s) of Ultra-High Energy Cosmic Rays (UHECR). Using current technologies however, achieving the necessary statistics may be financially and practically impossible. We describe the status and plans of the TARA project, an effort to detect Ultra-High-Energy Cosmic Rays by their forward scattered or “bistatic” radar signature. Bistatic radar holds promise as a new remote sensing technique for UHECR, without the duty cycle limitations of nitrogen fluorescence detectors. Such a technique could prove key in advancing the study of UHECR beyond the constraints of the current generation of cosmic ray observatories. TARA consists of a low-VHF television transmitter illuminating the air above the Telescope Array (TA), and a set of radio receivers on the far side of TA approximately 50 km distant from the transmitter. We have collected radar data since April 2011 using a 2 kW transmitter at 54.1 MHz. Recently, we received permission to increase our broadcast power to 40 kW and our effective radiated power (ERP) to 6 MW. On the receiver end, we are employing software-defined radio receivers and developing real-time trigger algorithms based on the expected air shower radar echo. In addition to presenting an overview of the project status and future plans, we will present the most recent results of searches for coincidences between radar echoes and Telescope Array air shower events.
Najdeno v: ključnih besedah
Ključne besede: UHECR, cosmic rays, radar detection
Objavljeno: 29.04.2020; Ogledov: 1434; Prenosov: 60
.pdf Polno besedilo (623,59 KB)

Air Shower Detection by Bistatic Radar
J. P. Lundquist, M. Abou Bakr Othman, 2011, objavljeni znanstveni prispevek na konferenci

Opis: Progress in the field of high‐energy cosmic rays is currently limited by the rarity of the most interesting rays striking the Earth. Indeed, the continuation of the field beyond the current generation of observatories may become financially and practically impossible if new ways are not found to achieve remote coverage over large portions of the Earth’s surface. We describe the development of an observatory based on such a new technique: the remote sensing via bistatic radar technology of cosmic ray induced extensive air showers. We build on pilot studies performed by MARIACHI which have demonstrated that air shower radar echoes are detectable, the opportunity afforded by the location of the Northern Hemisphere’s largest “conventional” cosmic ray observatory (The Telescope Array) in radio‐quiet western Utah, and the donation of analog television transmission equipment to this effort by a local television station.
Najdeno v: ključnih besedah
Ključne besede: UHECR, Remote sensing, Television broadcasting, Cosmic rays, General procedures and instrumentation, Radar telescopes
Objavljeno: 29.04.2020; Ogledov: 1424; Prenosov: 0
.pdf Polno besedilo (4,99 MB)

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