Abstract
Operating since 2004, the Pierre Auger Observatory has yielded several important results. The suppression of the flux around 5×10
19
eV is now confirmed without any doubt, a large-scale ...dipole anisotropy has been found for energies above 8×10
18
eV, as well as an indication for some intermediate-scale anisotropy at the highest energies. Furthermore, strong limits have been placed on ultra-high-energy photons and neutrinos. In order to elucidate the origin of the flux suppression at the highest energies and search for composition-enhanced anisotropies, the Auger Collaboration is currently upgrading the Observatory. In the framework of the upgrade, called AugerPrime, the array of 1660 water-Cherenkov detectors is equipped with plastic scintillators, allowing us to enhance the composition sensitivity. The station electronics is also upgraded, including better timing with up-to-date GPS receivers, higher sampling frequency, and increased dynamic range. Currently, more than 40% of the surface detectors have been upgraded, and the commissioning studies are well advanced. In this paper, the design of the AugerPrime surface detectors will be presented, and the performance obtained from the analysis of the first data will be discussed.
Recent microscopic and phenomenological calculations of giant dipole resonances for
A
⩽
56 nuclei are presented. The derived photodisintegration cross sections are exhaustively compared to the ...photonuclear data available to date. An accurate description of the data is found. Our new calculations are also compared with the previous and widely-used estimates of Puget, Stecker and Bredekamp. The present calculations also include all the possible paths down the nuclear chart. The impact on the photodisintegration of ultra-high-energy cosmic rays (UHECR) is illustrated for a Fe source with typical energies of 10
20–10
21
eV. At energies around 10
20
eV, the new cross sections are found to modify the UHECR photodisintegration rates. At energies around 10
21
eV, it is recommended to solve a full reaction network to estimate the photodisintegration rate of the UHECR.
Calibration of the surface array of the Pierre Auger Observatory Bertou, X.; Allison, P.S.; Bonifazi, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2006, Letnik:
568, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The Pierre Auger Observatory is designed to study cosmic rays of the highest energies
(
>
10
19
eV
)
. The ground array of the Observatory will consist of 1600 water Cherenkov detectors deployed over
...3000
km
2
. The remoteness and large number of detectors require a robust, automatic self-calibration procedure. It relies on the measurement of the average charge collected by a photomultiplier tube from the Cherenkov light produced by a vertical and central through-going muon, determined to 5–10% at the detector via a novel rate-based technique and to 3% precision through analysis of histograms of the charge distribution. The parameters needed for the calibration are measured every minute, allowing for an accurate determination of the signals recorded from extensive air showers produced by primary cosmic rays. The method also enables stable and uniform triggering conditions to be achieved.
Proton elastic and inelastic scattering angular distributions to the 2
+
1 and the 3
−
1 states for the neutron-rich nucleus
20
O were measured with a secondary beam using the MUST silicon strip ...detector array. Data for
18
O were also obtained for comparison. A phenomenological analysis has been used to deduce the deformation parameters
β
p,p′ for the collective excitations. Matter and transition densities were generated from self-consistent QRPA calculations. DWBA calculations using microscopic optical potentials obtained with these densities and the JLM interaction are compared to the data. The isovector character of the 2
+
1 state in
20
O is confirmed and predictions are discussed for the properties of the heavier neutron-rich oxygen isotopes.
Proton-rich isotopes of Ga, Ge, As, Se and Br had their total reaction cross sections (
σ
R
) measured. Root-mean-squared matter radii were determined from Glauber model calculations, which ...reproduced the experimental
σ
R
values. For all isotopic series a decrease of the
r
rms with increasing neutron number was observed.
Measurement of performance of the NectarCAM photodetectors Tsiahina, A.; Jean, P.; Olive, J.-F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2021, Letnik:
1007
Journal Article
Recenzirano
Odprti dostop
NectarCAM is a camera for the medium-sized telescopes of the Cherenkov Telescope Array (CTA), which covers the energy range of 100 GeV to 30 TeV. The camera is equipped with 265 focal plane modules ...(FPMs). Each FPM comprises 7 pixels, each consisting of a photo-multiplier tube, a preamplifier, an independently controlled power supply, and a common control system. We developed a dedicated test bench to validate and qualify the industrial FPM production and to measure the performance of each FPM in a dark room before its integration in the camera. We report the measured performance of 61 FPM prototypes obtained with our experimental setup. We demonstrate that the gains of the photo multiplier tubes are stable and that pulse widths, transit time spreads, afterpulse rates and charge resolutions are within the specifications for NectarCAM.
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