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1.
Measurements of Xmax above 10[sup]17 eV with the fluorescence detector of the Pierre Auger Observatory
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Alessio Porcelli, 2015, objavljeni znanstveni prispevek na konferenci

Opis: For the first time the Pierre Auger Collaboration presents〈Xmax〉and σ(Xmax) measurements covering nearly three decades of energy. In this analysis we include new Xmax data obtained with the High Elevation Auger Telescopes (HEAT) enhancement. The HEAT telescopes cover a field of view ranging from 30◦ to 60◦ of elevation and are located next to one of the standard fluorescence detector sites (Coihueco). The combination of the HEAT and Coihueco telescopes covers a field of view from ∼2◦ up to ∼60◦ of elevation. Thus, the combination can sample the longitudinal profile of nearby lower energy showers, allowing us to extend the energy range down to 10[sup]17 eV.
Najdeno v: ključnih besedah
Povzetek najdenega: ... extensive atmospheric showers, longitudinal shower profile, depth of the shower...
Ključne besede: extensive atmospheric showers, longitudinal shower profile, depth of the shower maximum, Pierre Auger Observatory
Objavljeno: 03.03.2016; Ogledov: 1851; Prenosov: 124
.pdf Polno besedilo (718,30 KB)

2.
Search for Ultra-relativistic Magnetic Monopoles with the Pierre Auger Observatory
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Toshihiro Fujii, 2015, objavljeni znanstveni prispevek na konferenci

Opis: Ultra-relativistic magnetic monopoles, possibly a relic of phase transitions in the early universe, would deposit an amount of energy comparable to UHECRs in their passage through the atmosphere, producing highly distinctive air shower profiles. We have performed a search for ultra-relativistic magnetic monopoles in the sample of air showers with profiles measured by the fluorescence detector of the Pierre Auger Observatory. No candidate was found to satisfy our selection criteria and we establish upper limits on the flux of ultra-relativistic magnetic monopoles - the first from an UHECR detector - improving over previous results by up to an order of magnitude.
Najdeno v: ključnih besedah
Povzetek najdenega: ...ultra-relativistic magnetic monopoles, extensive air showers, Pierre Auger Observatory...
Ključne besede: ultra-relativistic magnetic monopoles, extensive air showers, Pierre Auger Observatory
Objavljeno: 03.03.2016; Ogledov: 1459; Prenosov: 85
.pdf Polno besedilo (188,24 KB)

3.
Azimuthal asymmetry in the risetime of the Surface Detector signals of the Pierre Auger Observatory
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Ignacio Minaya, 2015, objavljeni znanstveni prispevek na konferenci

Opis: The azimuthal asymmetry in the risetime of signals in Auger surface detector stations is a source of information on shower development. The azimuthal asymmetry is due to a combination of the longitudinal evolution of the shower and geometrical effects related to the angles of incidence of the particles into the detectors. The magnitude of the effect depends upon the zenith angle and state of development of the shower and thus provides a novel observable sensitive to the mass composition of cosmic rays above 3 × 10[sup]18 eV. By comparing measurements with predictions from shower simulations, we find for both of our adopted models of hadronic physics (QGSJetII- 04 and Epos-LHC) an indication that the mean cosmic-ray mass increases with energy, as has been inferred from other studies. However the absolute values derived for the mass are dependent on the shower model and on the range of distance from the shower core selected. Thus the method has uncovered further deficiencies in our understanding of shower modelling that must be resolved before the mass composition can be inferred from (sec θ)max.
Najdeno v: ključnih besedah
Povzetek najdenega: ...vatory, Surface Detector, risetime of detector signal, azimuthal asymmetry, extensive air showers...
Ključne besede: Pierre Auger Observatory, Surface Detector, risetime of detector signal, azimuthal asymmetry, extensive air showers
Objavljeno: 03.03.2016; Ogledov: 1513; Prenosov: 86
.pdf Polno besedilo (243,04 KB)

4.
Extension of the measurement of the proton-air cross section with the Pierre Auger Observatory
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Ralf Ulrich, 2015, objavljeni znanstveni prispevek na konferenci

Opis: With hybrid data of the Pierre Auger Observatory it is possible to measure the cross section of proton-air collisions at energies far beyond the reach of the LHC. Since the first measurement by the Pierre Auger Collaboration the event statistics has increased significantly. The proton-air cross section is now estimated in the two energy intervals in lg(E/eV) from 17.8 to 18 and from 18 to 18.5. These energies are chosen so that they maximise the available event statistics and at the same time lie in the region most compatible with a significant primary proton fraction. Of these data, only the 20% of most proton-like events are considered for the measurement. Furthermore, with a new generation of hadronic interaction models which have been tuned to LHC data, the model-dependent uncertainties of the measurement are re-visited.
Najdeno v: ključnih besedah
Povzetek najdenega: ...Pierre Auger Observatory, extensive air showers, proton-air cross section, hadronic interaction models...
Ključne besede: Pierre Auger Observatory, extensive air showers, proton-air cross section, hadronic interaction models
Objavljeno: 03.03.2016; Ogledov: 1355; Prenosov: 89
.pdf Polno besedilo (114,02 KB)

5.
Measurement of the average electromagnetic longitudinal shower profile at the Pierre Auger Observatory
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Francisco Diogo, 2015, objavljeni znanstveni prispevek na konferenci

Opis: In addition to the standard Xmax and energy, the longitudinal profiles of extensive air showers contain some more interesting information. For energies above 10[sup]17.8 eV, we present the average profiles as a function of atmospheric depth measured for the first time at the Pierre Auger Observatory. The profile shapes for different energy ranges are all well reproduced by a Gaisser-Hillas function within the range studied. A detailed analysis of the systematic uncertainties is performed using data and a full detector simulation, and the results are compared with predictions of hadronic interaction models for different primaries.
Najdeno v: ključnih besedah
Povzetek najdenega: ...standard Xmax and energy, the longitudinal profiles of extensive air showers contain some more interesting information....
Ključne besede: Pierre Auger Observatory, extensive air showers, longitudinal shower profile, Gaisser-Hillas finction
Objavljeno: 03.03.2016; Ogledov: 1262; Prenosov: 87
.pdf Polno besedilo (684,20 KB)

6.
Studies in the atmospheric monitoring at the Pierre Auger Observatory using the upgraded Central Laser Facility
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Carlos Medina-Hernandez, 2015, objavljeni znanstveni prispevek na konferenci

Opis: The Fluorescence Detector (FD) at the Pierre Auger Observatory measures the intensity of the scattered light from laser tracks generated by the Central Laser Facility (CLF) and the eXtreme Laser Facility (XLF) to monitor and estimate the vertical aerosol optical depth (τ(z,t)). This measurement is needed to obtain unbiased and reliable FD measurements of the arrival direction and energy of the primary cosmic ray, and the depth of the maximum shower development. The CLF was upgraded substantially in 2013 with the addition of a solid state laser, new generation GPS, a robotic beam calibration system, better thermal and dust isolation, and improved software. The upgrade also included a back-scatter Raman LIDAR to measure τ(z,t). The new features and applications of the upgraded instrument are described. These include the laser energy calibration and the atmospheric monitoring measurements. The first τ(z,t) results and comparisons after the upgrade are presented using different methods. The first method compares the FD hourly response to the scattered light from the CLF (or XLF) against a reference hourly profile measured during a clear night where zero aerosol contents are assumed. The second method simulates FD responses with different atmospheric parameters and selects the parameters that provide the best fit to the actual FD response. A third method uses the new Raman LIDAR receiver in-situ to measure the back-scatter light from the CLF laser. The results show a good data agreement for the first and second methods using FD stations located at the same distance from the facilities. Preliminary results of τ(z,t) using the Raman LIDAR are presented as well.
Najdeno v: ključnih besedah
Povzetek najdenega: ...Pierre Auger Observatory, extensive air showers, the Fluorescence Detector, atmospheric monitoring, vertical aer...
Ključne besede: Pierre Auger Observatory, extensive air showers, the Fluorescence Detector, atmospheric monitoring, vertical aerosol optical depth, the Central Laser Facility, the eXtreme Laser Facility
Objavljeno: 03.03.2016; Ogledov: 1461; Prenosov: 87
.pdf Polno besedilo (3,96 MB)

7.
The Energy Content of Extensive Air Showers in the Radio Frequency Range of 30-80 MHz
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Christian Glaser, 2015, objavljeni znanstveni prispevek na konferenci

Opis: At the Auger Engineering Radio Array (AERA) of the Pierre Auger Observatory, we have developed a new method to measure the total amount of energy that is transferred from the primary cosmic ray into radio emission. We find that this radiation energy is an estimator of the cosmic ray energy. It scales quadratically with the cosmic ray energy, as expected for coherent emission. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicular to the geomagnetic field at the Auger site, in the frequency band of the detector from 30 to 80 MHz. These observations are compared to the data of the surface detector of the Observatory, which provide well-calibrated energies and arrival directions of the cosmic rays. We find energy resolutions of the radio reconstruction of 22% for the complete data set, and 17% for a high-quality subset containing only events with at least five stations with signal.
Najdeno v: ključnih besedah
Ključne besede: Pierre Auger Observatory, the Auger Engineering Radio Array (AERA), extensive air showers, radio reconstruction: energy resolution
Objavljeno: 03.03.2016; Ogledov: 1364; Prenosov: 92
.pdf Polno besedilo (574,66 KB)

8.
Status and Prospects of the Auger Engineering Radio Array
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Johannes Schulz, 2015, objavljeni znanstveni prispevek na konferenci

Opis: The Auger Engineering Radio Array (AERA) is an extension of the Pierre Auger Observatory. It is used to detect radio emission from extensive air showers in the 30 - 80 MHz frequency band. A focus of interest is the dependence of the radio emission on shower parameters such as the energy and the atmospheric depth of the shower maximum. After three phases of deployment, AERA now consists of 153 autonomous radio stations with different spacings, covering an area of about 17 km2. The size, station spacings, and geographic location at the same site or near other Auger extensions, are all targeted at cosmic ray energies above 10[sup]17 eV. The array allows us to explore different technical schemes to measure the radio emission as well as to cross calibrate our measurements with the established baseline detectors of the Auger Observatory. We present the most recent technological developments and selected experimental results obtained with AERA.
Najdeno v: ključnih besedah
Povzetek najdenega: ...is used to detect radio emission from extensive air showers in the 30 - 80...
Ključne besede: Pierre Auger Observatory, the Auger Engineering Radio Array (AERA), radio emission from extensive air showers, detector cross-calibration
Objavljeno: 03.03.2016; Ogledov: 1531; Prenosov: 81
.pdf Polno besedilo (2,79 MB)

9.
Report of the Working Group on the Composition of Ultra-High Energy Cosmic Rays
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Michael Unger, 2015, objavljeni znanstveni prispevek na konferenci

Opis: The atmospheric depth, Xmax, at which the particle number of an air shower reaches its maximum is a good indicator for the mass of the primary particle. We present a comparison of the energy evolution of the mean of Xmax as measured by the Telescope Array and c Collaborations. After accounting for the different resolutions, acceptances and analysis strategies of the two experiments, the two results are found to be in good agreement within systematic uncertainties.
Najdeno v: ključnih besedah
Povzetek najdenega: ...ory, Telescope Array, Ultra-High Energy Cosmic Rays, elemental composition, extensive air showers, the atmospheric depth of the...
Ključne besede: Pierre Auger Observatory, Telescope Array, Ultra-High Energy Cosmic Rays, elemental composition, extensive air showers, the atmospheric depth of the air shower maximum
Objavljeno: 08.03.2016; Ogledov: 1526; Prenosov: 130
.pdf Polno besedilo (329,86 KB)

10.
Initial results of a direct comparison between the Surface Detectors of the Pierre Auger Observatory and the Telescope Array
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, R. Takeishi, 2015, objavljeni znanstveni prispevek na konferenci

Opis: The Pierre Auger Observatory (Auger) in Mendoza, Argentina and the Telescope Array (TA) in Utah, USA aim at unraveling the origin and nature of Ultra-High Energy Cosmic Rays (UHECR). At present, there appear to be subtle differences between Auger and TA results and interpretations. Joint working groups have been established and have already reported preliminary findings. From an experimental standpoint, the Surface Detectors (SD) of both experiments make use of different detection processes not equally sensitive to the components of the extensive air showers making it to the ground. In particular, the muonic component of the shower measured at ground level can be traced back to the primary composition, which is critical for understanding the origin of UHECRs. In order to make direct comparisons between the SD detection techniques used by Auger and TA, a joint SD experimental research program is being developed. In the first phase, two Auger SD stations were deployed at the TA Central Laser Facility to compare station-level responses. This paper concentrates on the results obtained with the first Auger SD station (an “Auger North” design), which has been operating since October 2014. The second Auger SD station, identical to the ones being operated at Auger in Argentina (an “Auger South” design), was just deployed in June 2015. The second phase of this research program will be to co-locate six Auger North SD stations with TA stations in the field to compare event-level responses.
Najdeno v: ključnih besedah
Povzetek najdenega: ...not equally sensitive to the components of the extensive air showers making it to the ground....
Ključne besede: Ultra-High Energy Cosmic Rays, Pierre Auger Observatory, Telescope Array, extensive air showers, secondary cosmic rays, muonic shower component, surface detectors
Objavljeno: 08.03.2016; Ogledov: 1442; Prenosov: 88
.pdf Polno besedilo (1,42 MB)

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