ABSTRACT This paper reports on the measurement of the large-scale anisotropy in the distribution of cosmic-ray arrival directions using the data collected by the air shower detector ARGO-YBJ from ...2008 January to 2009 December, during the minimum of solar activity between cycles 23 and 24. In this period, more than 2 × 1011 showers were recorded with energies between ∼1 and 30 TeV. The observed two-dimensional distribution of cosmic rays is characterized by two wide regions of excess and deficit, respectively, both of relative intensity ∼10−3 with respect to a uniform flux, superimposed on smaller size structures. The harmonic analysis shows that the large-scale cosmic-ray relative intensity as a function of R.A. can be described by the first and second terms of a Fouries series. The high event statistics allow the study of the energy dependence of the anistropy, showing that the amplitude increases with energy, with a maximum intensity at ∼10 TeV, and then decreases while the phase slowly shifts toward lower values of R.A. with increasing energy. The ARGO-YBJ data provide accurate observations over more than a decade of energy around this feature of the anisotropy spectrum.
This paper reports on the observation of the sidereal large-scale anisotropy of cosmic rays using data collected by the ARGO-YBJ experiment over 5 years (2008-2012). This analysis extends previous ...work limited to the period from 2008 January to 2009 December, near the minimum of solar activity between cycles 23 and 24. With the new data sample, the period of solar cycle 24 from near minimum to maximum is investigated. A new method is used to improve the energy reconstruction, allowing us to cover a much wider energy range, from 4 to 520 TeV. Below 100 TeV, the anisotropy is dominated by two wide regions, the so-called "tail-in" and "loss-cone" features. At higher energies, a dramatic change of the morphology is confirmed. The yearly time dependence of the anisotropy is investigated. Finally, no noticeable variation of cosmic-ray anisotropy with solar activity is observed for a median energy of 7 TeV.
JEM-EUSO is an international program for the development of space-based Ultra-High Energy Cosmic Ray observatories. The program consists of a series of missions which are either under development or ...in the data analysis phase. All instruments are based on a wide-field-of-view telescope, which operates in the near-UV range, designed to detect the fluorescence light emitted by extensive air showers in the atmosphere. We describe the simulation software ESAF in the framework of the JEM-EUSO program and explain the physical assumptions used. We present here the implementation of the JEM-EUSO, POEMMA, K-EUSO, TUS, Mini-EUSO, EUSO-SPB1 and EUSO-TA configurations in ESAF. For the first time ESAF simulation outputs are compared with experimental data.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
At the Testa Grigia high altitude research Station (3480 m. a.s.l, Italy, 45°57′ N, 7°42’ E) several dosimetric campaigns for the measurement of the dose due to secondary neutrons produced in the ...atmosphere and in the surrounding environment by primary cosmic rays have been carried out from 2014 until 2021. Because of the high altitude of the site, the neutron flux at Testa Grigia is 10–15 times higher than at the sea level. Various instruments has been used to evaluate the dependence of the ambient dose equivalent rate from different factors as atmospheric parameters, environmental conditions and solar activity. Moreover, since October 2014 a modular neutron monitor designed, realized and tested by the SVIRCO Observatory Group INAF-IAPS in Rome, is permanently operating in the laboratory, providing a continuous monitoring of primary cosmic ray variability and making the laboratory an ideal place for dosimetric studies, instrument calibration and “in field” tests. In this paper the results of several neutron measurements carried out in the last years in periods of different solar activity and environmental conditions are reported, with a discussion on the origin of the observed variations of the ambient dose equivalent rate.
•The dose rate due to secondary cosmic rays neutrons is monitored at the Testa Grigia Laboratory.•Neutron dose rate variations are studied in different environmental conditions.•The sensitivity of different neutron detectors to neutron flux variations is studied.
We present a novel approach to the determination of the pointing of Imaging Atmospheric Cherenkov Telescopes (IACTs) using the trajectories of the stars in their camera’s field of view. The method ...starts with the reconstruction of the star positions from the Cherenkov camera data, taking into account the point spread function of the telescope, to achieve a satisfying reconstruction accuracy of the pointing position. A simultaneous fit of all reconstructed star trajectories is then performed with the orthogonal distance regression (ODR) method. ODR allows us to correctly include the star position uncertainties and use the time as an independent variable. Having the time as an independent variable in the fit makes it better suitable for various star trajectories. This method can be applied to any IACT and requires neither specific hardware nor interface or special data-taking mode. In this paper, we use the Large-Sized Telescope (LST) data to validate it as a useful tool to improve the determination of the pointing direction during regular data taking. The simulation studies show that the accuracy and precision of the method are comparable with the design requirements on the pointing accuracy of the LST (≤14″). With the typical LST event acquisition rate of 10 kHz, the method can achieve up to 50 Hz pointing monitoring rate, compared to ??(1) Hz achievable with standard techniques. The application of the method to the LST prototype (LST-1) commissioning data shows the stable pointing performance of the telescope.
The hadronic interaction of cosmic rays with solar atmosphere can produce high energy gamma-rays. The gamma-ray luminosity is correlated both with the flux of primary cosmic rays and the intensity of ...the solar magnetic field. The gamma-rays below 200 GeV have been observed by Fermi without any evident energy cutoff. The bright gamma-ray flux above 100 GeV has been detected only during solar minimum. The only available data in the TeV range come from the HAWC observations, however, outside the solar minimum. The ARGO-YBJ data set has been used to search for sub-TeV/TeV gamma-rays from the Sun during the solar minimum from 2008 to 2010, the same time period covered by the Fermi data. A suitable model containing the Sun shadow, solar disk emission, and inverse-Compton emission has been developed, and the chi-square minimization method was used to quantitatively estimate the disk gamma-ray signal. The result shows that no significant gamma-ray signal is detected and upper limits to the gamma-ray flux at 0.3-7 TeV are set at the 95% confidence level. In the low energy range these limits are consistent with the extrapolation of the Fermi-LAT measurements taken during solar minimum and are compatible with a softening of the gamma-ray spectrum below 1 TeV. They also provide an experimental upper bound to any solar disk emission at TeV energies. Models of dark matter annihilation via long-lived mediators predicting gamma-ray fluxes >10−7 GeV cm−2 s−1 below 1 TeV are ruled out by the ARGO-YBJ limits.
The ARGO-YBJ detector, located at the Yangbajing Cosmic Ray Laboratory (4300 m a. s. l., Tibet, China), was a "full coverage" (central carpet with an active area of ∼93%) air shower array dedicated ...to gamma-ray astronomy and cosmic-ray studies. The wide field of view (∼2 sr) and high duty cycle (>86%), made ARGO-YBJ suitable to search for short and unexpected gamma-ray emissions like gamma-ray bursts (GRBs). Between 2007 November 6 and 2013 February 7, 156 satellite-triggered GRBs (24 of them with known redshift) occurred within the ARGO-YBJ field of view (zenith angle θ ≤ 45°). A search for possible emission associated with these GRBs has been made in the two energy ranges 10-100 GeV and 10-1000 GeV. No significant excess has been found in time coincidence with the satellite detections nor in a set of different time windows inside the interval of one hour after the bursts. Taking into account the EBL absorption, upper limits to the energy fluence at a 99% confidence level have been evaluated, with values ranging from ∼10−5 erg cm−2 to ∼10−1 erg cm−2. The Fermi-GBM burst GRB 090902B, with a high-energy photon of 33.4 GeV detected by Fermi-LAT, is discussed in detail.
Abstract
The complexity of modern cosmic ray observatories and the
rich data sets they capture often require a sophisticated software
framework to support the simulation of physical processes, ...detector
response, as well as reconstruction and analysis of real and
simulated data. Here we present the EUSO-Offline framework. The
code base was originally developed by the Pierre Auger
Collaboration, and portions of it have been adopted by other
collaborations to suit their needs. We have extended this software
to fulfill the requirements of Ultra-High Energy Cosmic Ray
detectors and very high energy neutrino detectors developed for the
Joint Exploratory Missions for an Extreme Universe Observatory
(JEM-EUSO). These path-finder instruments constitute a program to
chart the path to a future space-based mission like POEMMA. For
completeness, we describe the overall structure of the framework
developed by the Auger collaboration and continue with a description
of the JEM-EUSO simulation and reconstruction capabilities. The
framework is written predominantly in modern C++ (compliled against
C++17) and incorporates third-party libraries chosen based on
functionality and our best judgment regarding support and
longevity. Modularity is a central notion in the framework design, a
requirement for large collaborations in which many individuals
contribute to a common code base and often want to compare different
approaches to a given problem. For the same reason, the framework is
designed to be highly configurable, which allows us to contend with
a variety of JEM-EUSO missions and observation scenarios. We also
discuss how we incorporate broad, industry-standard testing coverage
which is necessary to ensure quality and maintainability of a
relatively large code base, and the tools we employ to support a
multitude of computing platforms and enable fast, reliable
installation of external packages. Finally, we provide a few
examples of simulation and reconstruction applications using
EUSO-Offline.
Layout and performance of RPCs used in the Argo-YBJ experiment Aielli, G.; Assiro, R.; Bacci, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2006, Letnik:
562, Številka:
1
Journal Article
Recenzirano
The layout of the RPCs, used in the Argo-YBJ experiment to image with a high space-time granularity the atmospheric shower, is described in this paper. The detector has been assembled to provide both ...digital and analog informations in order to cover a wide particle density range with a time accuracy of 1
ns. The experimental results obtained operating the chambers in streamer mode at sea level with a standard gas mixture are presented.
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