arXiv subjects

R. Caruso

Publications and source records attributed to R. Caruso.

149 records · Page 9Linked to original sources

arXiv2009

Upper limit on the cosmic-ray photon fraction at EeV energies from the Pierre Auger Observatory

From direct observations of the longitudinal development of ultra-high energy air showers performed with the Pierre Auger Observatory, upper limits of 3.8%, 2.4%, 3.5% and 11.7% (at 95% c.l.) are obtained on the fraction of cosmic-ray photons above 2, 3, 5 and 10 EeV (1 EeV = 10^18 eV) respectively. These are the first experimental limits on ultra-high energy photons at energies below 10 EeV. The results complement previous constraints on top-down models from array data and they reduce systematic uncertainties in the interpretation of shower data in terms of primary flux, nuclear composition and proton-air cross-section.

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arXiv2007

The Absolute, Relative and Multi-Wavelength Calibration of the Pierre Auger Observatory Fluorescence Detectors

Absolute calibration of the Pierre Auger Observatory fluorescence detectors uses a 375 nm light source at the telescope aperture. This end-to-end technique accounts for the combined effects of all detector components in a single measurement. The relative response has been measured at wavelengths of 320, 337, 355, 380 and 405 nm, defining a spectral response curve which has been normalized to the absolute calibration. Before and after each night of data taking a relative calibration of the phototubes is performed. This relative calibration is used to track both short and long term changes in the detector's response. A cross check of the calibration in some phototubes is performed using an independent laser technique. Overall uncertainties, current results and future plans are discussed.

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arXiv2005

Optical Relative Calibration and Stability Monitoring for the Auger Fluorescence Detector

The stability of the fluorescence telescopes of the Pierre Auger Observatory is monitored with the optical relative calibration setup. Optical fibers distribute light pulses to three different diffuser groups within the optical system. The total charge per pulse is measured for each pixel and compared with reference calibration measurements. This allows monitoring the short and long term stability with respect of the relative timing between pixels and the relative gain for each pixel. The designs of the LED calibration unit (LCU) and of the Xenon flash lamp used for relative calibration, are described and their capabilities to monitor the stability of the telescope performances are studied. We report the analysis of relative calibration data recorded during 2004. Fluctuations in the relative calibration constants provide a measure of the stability of the FD.

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arXiv2005

Quality studies of the data taking conditions for the Auger Fluorescence Detector

As more than half of the Fluorescence Detector (FD) of the Auger Observatory is completed, data taking is becoming a routine job. It is then necessary to follow strict procedures to assure the quality of the data. An overview of the data taking methods is given. The nature of the FD background signal is due to the night sky brightness (stars and planet faint light, moonlight, twilight, airglow, zodiacal and artificial light) and to the electronic background (photomultiplier and electronic noise). The analysis of the fluctuations in the FADC signal (variance analysis), directly proportional to the background mean light level, performed for each night of data taking is used to monitor the FD background signal. The data quality is analysed using different techniques, described in detail. Examples of trigger rates, number of stereo events, dead time due to moonlight, weather or hardware problems are given. The analysis comprises several months of data taking, giving an overview of the FD capabilities, performance and allowing a systematic study of data and their correlation with the environment.

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arXiv2005

Measurement of the Sky Photon Background Flux at the Auger Observatory

The sky photon background flux has been measured at the southern Auger site in Malargue, Argentina, using the observatory's fluorescence detectors (FD). The analysis is based on ADC variances of pixels not triggered by the First Level Trigger. Photon fluxes are calculated for each individual pixel at each telescope. The statistics from each night of data taking allows a study of local variations in the photon flux. Results show a clear dependence of the flux on elevation angle. Time variations, possibly related to different atmospheric conditions, do not mask this dependence. In particular the flux excess above the horizon shows a rather stable and reproducible behaviour with elevation. Correlation of this dependence with atmospheric parameters can be of interest as it offers the promise of extracting those parameters directly from FD data, thus allowing cross checks with independent methods based on different monitoring devices.

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