390 research outputs found
The Offline Software Framework of the Pierre Auger Observatory
To be published in the ProceedingsInternational audienceThe Pierre Auger Observatory is designed to unveil the nature and the origins of the highest energy cosmic rays. The large and geographically dispersed collaboration of physicists and the wide-ranging collection of simulation and reconstruction tasks pose some special challenges for the offline analysis software. We have designed and implemented a general purpose framework which allows collaborators to contribute algorithms and sequencing instructions to build up the variety of applications they require. The framework includes machinery to manage these user codes, to organize the abundance of user-contributed configuration files, to facilitate multi-format file handling, and to provide access to event and time-dependent detector information which can reside in various data sources. A number of utilities are also provided, including a novel geometry package which allows manipulation of abstract geometrical objects independent of coordinate system choice. The framework is implemented in C++, and takes advantage of object oriented design and common open source tools, while keeping the user side simple enough for C++ novices to learn in a reasonable time. The distribution system incorporates unit and acceptance testing in order to support rapid development of both the core framework and contributed user code
Ramsauer approach to Mie scattering of light on spherical particles
The scattering of an electromagnetic plane wave by a spherical particle was
solved analytically by Gustav Mie in 1908. The Mie solution is expressed as a
series with very many terms thus obscuring the physical interpretations of the
results. The purpose of the paper is to try to illustrate this phenomenon
within the Ramsauer framework used in atomic and nuclear physics. We show that
although the approximations are numerous, the Ramsauer analytical formulae
describe fairly well the differential and the total cross sections. This allows
us to propose an explanation for the origin of the different structures in the
total cross section
Radio emission of extensive air shower at CODALEMA: Polarization of the radio emission along the v*B vector
Cosmic rays extensive air showers (EAS) are associated with transient radio
emission, which could provide an efficient new detection method of high energy
cosmic rays, combining a calorimetric measurement with a high duty cycle. The
CODALEMA experiment, installed at the Radio Observatory in Nancay, France, is
investigating this phenomenon in the 10^17 eV region. One challenging point is
the understanding of the radio emission mechanism. A first observation
indicating a linear relation between the electric field produced and the cross
product of the shower axis with the geomagnetic field direction has been
presented (B. Revenu, this conference). We will present here other strong
evidences for this linear relationship, and some hints on its physical origin.Comment: Contribution to the 31st International Cosmic Ray Conference, Lodz,
Poland, July 2009. 4 pages, 8 figures. v2: Typo fixed, arxiv references adde
Slewing Mirror Telescope and the Data-Acquisition System for the UFFO-Pathfinder
The Ultra-Fast Flash Observatory (UFFO) aims to detect the earliest moment of Gamma-Ray
Bursts (GRBs) which is not well known, resulting into the enhancement of GRB mechanism
understanding. The pathfinder mission was proposed to be a scaled-down version of UFFO,
and only contains the UFFO Burst Alert & Trigger Telescope (UBAT) measuring the
X-ray/gamma-ray with the wide-field of view and the Slewing Mirror Telescope (SMT) with a
rapid-response for the UV/optical photons. Once the UBAT detects a GRB candidate with the
position accuracy of 10 arcmin, the SMT steers the UV/optical photons from the candidate
to the telescope by the fast rotatable mirror and provides the early UV/optical photons
measurements with 4 arcsec accuracy. The SMT has a modified Ritchey-ChrĂštien telescope
with the aperture size of 10 cm diameter including the rotatable mirror and the image
readout by the intensified charge-coupled device. There is a key board called the UFFO
Data Acquisition system (UDAQ) that manages the communication of each telescope and also
of the satellite and the UFFO overall operation. This pathfinder is designed and built
within the limited size and weight of  ~20 kg and the low power consumption up to
 ~30 W. We will discuss the design and performance of the UFFO-pathfinder, and its
integration to the Lomonosov satellite
Global Description of EUSO-Balloon Instrument
For the JEM-EUSO CollaborationThe EUSO-Balloon is a pathfinder of the JEM-EUSO mission, designed to be installed on-board the International Space Station before the end of this decade. The EUSO-Balloon instrument, conceived as a scaleddown version of the main mission, is currently developed as a payload of a stratospheric balloon operated by CNES, and will, most likely, be launched during the CNES flight campaign in 2014. Several key elements of JEM-EUSO have been implemented in the EUSO-Balloon. The instrument consists of an UV telescope, made of three Fresnel lenses, designed to focus the signal of the UV tracks, generated by highly energetic cosmic rays propagating in the earth's atmosphere, onto a finely pixelized UV camera. In this contribution, we review the main stages of the signal processing of the EUSO-Balloon instrument: the photodetection, the analog electronics, the trigger stages, which select events while rejecting random background, the acquisition system performing data storage and the monitoring, which allows the instrument control during operation
Status report of the UFFO-pathfinder
For the UFFO CollaborationGamma-Ray Bursts (GRBs) are the most energetic explosions in the universe, their optical photon ïŹux rise very quickly, typically within one minute, then fall off gradually. Hundreds of GRBs optical light curves have been measured since the ïŹrst discovery of GRB in 1967. However, only a handful of measurements have been made within a minute after the gamma ray signal. Because of this drawback, the short-hard type GRBs and rapid-rising GRBs, which may account for 30% of all GRBs, remain practically unexplored. To reach sub-minute timescales, the Ultra-Fast Flash Observatory (UFFO) uses a rapidly moving mirror to redirect the optical beam instead of slewing the entire spacecraft. The ïŹrst realization of this concept is UFFO-pathïŹnder, which is equipped with fast-response Slewing Mirror Telescope (SMT) and a UFFO Burst Alert and Trigger Telescope (UBAT). SMT has a slewing mirror to redirect optical photons into a telescope and then record them by an intensiïŹed CCD. UBAT uses coded mask to provide X-ray trigger from a GRB and provides the GRB location for SMT. UFFOs sub-minute measurements of the optical emission of dozens of GRBs each year will result in a more rigorous test of current internal shock models, probe the extremes of bulk Lorentz factors, provide the ïŹrst early and detailed measurements of fast-rise GRB optical light curves, and help verify the prospect of GRB as a new standard candle. The UFFO-pathïŹnder is fully integrated with the Lomonosov satellite and is scheduled to be launched in late 2013 or early 2014. We will present the latest progress in this conference
The UFFO (Ultra Fast Flash Observatory) Pathfinder: Science and Mission
Hundreds of gamma-ray burst (GRB) optical light curves have been measured
since the discovery of optical afterglows. However, even after nearly 7 years
of operation of the Swift Observatory, only a handful of measurements have been
made soon (within a minute) after the gamma ray signal. This lack of early
observations fails to address burst physics at short time scales associated
with prompt emissions and progenitors. Because of this lack of sub-minute data,
the characteristics of the rise phase of optical light curve of short-hard type
GRB and rapid-rising GRB, which may account for ~30% of all GRB, remain
practically unknown. We have developed methods for reaching sub-minute and
sub-second timescales in a small spacecraft observatory. Rather than slewing
the entire spacecraft to aim the optical instrument at the GRB position, we use
rapidly moving mirror to redirect our optical beam. As a first step, we employ
motorized slewing mirror telescope (SMT), which can point to the event within
1s, in the UFFO Pathfinder GRB Telescope onboard the Lomonosov satellite to be
launched in Nov. 2011. UFFO's sub-minute measurements of the optical emission
of dozens of GRB each year will result in a more rigorous test of current
internal shock models, probe the extremes of bulk Lorentz factors, provide the
first early and detailed measurements of fast-rise GRB optical light curves,
and help verify the prospect of GRB as a new standard candle. We will describe
the science and the mission of the current UFFO Pathfinder project, and our
plan of a full-scale UFFO-100 as the next step.Comment: 4 pages, 5 figures, to appear in the 32nd International Conference on
Cosmic Rays (ICRC), Beijing, August 11-18, 201
Design and implementation of electronics and data acquisition system for Ultra-Fast Flash Observatory
The Ultra-Fast Flash Observatory (UFFO) Pathfinder for Gamma-Ray Bursts (GRBs) consists
of two telescopes. The UFFO Burst Alert & Trigger Telescope (UBAT) handles the
detection and localization of GRBs, and the Slewing Mirror Telescope (SMT) conducts the
measurement of the UV/optical afterglow. UBAT is equipped with an X-ray detector, analog
and digital signal readout electronics that detects X-rays from GRBs and determines the
location. SMT is equipped with a stepping motor and the associated electronics to rotate
the slewing mirror targeting the GRBs identified by UBAT. First the slewing mirror points
to a GRB, then SMT obtains the optical image of the GRB using the intensified CCD and its
readout electronics. The UFFO Data Acquisition system (UDAQ) is responsible for the
overall function and operation of the observatory and the communication with the satellite
main processor. In this paper we present the design and implementation of the electronics
of UBAT and SMT as well as the architecture and implementation of UDAQ
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