129 research outputs found
Cerenkov Events Seen by The TALE Air Fluorescence Detector
The Telescope Array Low-Energy Extension (TALE) is a hybrid, Air Fluorescence
Detector (FD) / Scintillator Array, designed to study cosmic ray initiated
showers at energies above eV. Located in the western Utah
desert, the TALE FD is comprised of 10 telescopes which cover the elevation
range 31-58 in addition to 14 telescopes with elevation coverage of
3-31.
As with all other FD's, a subset of the shower events recorded by TALE are
ones for which the Cerenkov light produced by the shower particles dominates
the total observed light signal. In fact, for the telescopes with higher
elevation coverage, low energy Cerenkov events form the vast majority of
triggered cosmic ray events. In the typical FD data analysis procedure, this
subset of events is discarded and only events for which the majority of signal
photons come from air fluorescence are kept.
In this talk, I will report on a study to reconstruct the "Cerenkov Events"
seen by the high elevation viewing telescopes of TALE. Monte Carlo studies and
a first look at real events observed by TALE look very promising. Even as a
monocular detector, the geometrical reconstruction method employed in this
analysis allows for a pointing accuracy on the order of a degree. Preliminary
Monte Carlo studies indicate that, the expected energy resolution is better
than 25. It may be possible to extend the low energy reach of TALE to below
eV. This would be the first time a detector designed specifically as
an air fluorescence detector is used as an imaging Cerenkov detector.Comment: Presentation at the DPF 2013 Meeting of the American Physical Society
Division of Particles and Fields, Santa Cruz, California, August 13-17, 2013.
5 pages, 2 figure
Studies of the nature of the low-energy, gamma-like background for Cherenkov Telescope Array
The upcoming Cherenkov Telescope Array (CTA) project is expected to provide
unprecedented sensitivity in the low-energy ( <~100 GeV) range for Cherenkov
telescopes. In order to exploit fully the potential of the telescopes the
standard analysis methods for gamma/hadron separation might need to be revised.
We study the composition of the background by identifying events composed
mostly of a single electromagnetic subcascade or double subcascade from a
{\pi}0 (or another neutral meson) decay. We apply the standard simulation and
analysis chain of CTA to evaluate the potential of the standard analysis to
reject such events.Comment: All CTA contributions at arXiv:1709.03483. Proc. of the 35th
International Cosmic Ray Conference, Busan, Kore
Prototype 9.7 m Schwarzschild-Couder telescope for the Cherenkov Telescope Array: status of the optical system
The Cherenkov Telescope Array (CTA) is an international project for a
next-generation ground-based gamma ray observatory, aiming to improve on the
sensitivity of current-generation experiments by an order of magnitude and
provide energy coverage from 30 GeV to more than 300 TeV. The 9.7m
Schwarzschild-Couder (SC) candidate medium-size telescope for CTA exploits a
novel aplanatic two-mirror optical design that provides a large field of view
of 8 degrees and substantially improves the off-axis performance giving better
angular resolution across all of the field of view with respect to
single-mirror telescopes. The realization of the SC optical design implies the
challenging production of large aspherical mirrors accompanied by a
submillimeter-precision custom alignment system. In this contribution we report
on the status of the implementation of the optical system on a prototype 9.7 m
SC telescope located at the Fred Lawrence Whipple Observatory in southern
Arizona.Comment: Proceedings of the 35th International Cosmic Ray Conference (ICRC
2017), Busan, Korea. All CTA contributions at arXiv:1709.0348
CPT and Lorentz violation in the electroweak sector
Long ago, Carroll, Field and Jackiw introduced CPT-violation in the photon sector by adding a dimension-3 gauge-invariant term parametrized by a constant four-vector parameter k(AF) to the usual (Maxwell) Lagrangian, deriving an ultra-tight bound from astrophysical data. Here, we will discuss recent work studying the extension of this term to the full electroweak gauge sector of the Standard Model. In the context of the Standard Model Extension, CPT and Lorentz violation arises from two gauge-invariant terms parametrized by the four vectors k(1) and k(2). First we will show how upon spontaneous breaking of the electroweak gauge symmetry these two terms yield Lorentz-violating terms for the photon and the W and Z bosons. As it turns out, the resulting modified dispersion relations for the W bosons yield spacelike momentum for one of its propagating modes at sufficiently large energy. This in turn allows for the possibility of Cherenkov-like W-boson emission by high-energy fermions such as protons, provoking their decay. Analysis of ultra-high-energy cosmic ray data allows for bounding the previously unbound parameter k(2), and, by combination with the ultra-tight bound on k(AF), the parameter k(1).Portuguese Fundacao para a Ciencia e a Tecnologia (FCT) - SFRH/BPD/101403/2014program POPH/FSE
New College of Floridainfo:eu-repo/semantics/publishedVersio
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