878 research outputs found
The Hybrid Exposure and Spectrum of the Pierre Auger Observatory
No full textThe Pierre Auger Observatory detects ultra-high energy cosmic rays by implementing two complementary air-shower measurements. The combination of the single tank information from the surface detector (SD) and the calorimetric measurements of the shower profile using the fluorescence detector (FD), known as the "hybrid" technique, provides a more reliable event reconstruction than using either detector alone. In this paper the approach used to measure the cosmic ray flux using this class of events is described. The analysis method is discussed considering its main steps: the event selection, the detector up time evaluation and the exposure calculation. © 2009 Elsevier B.V
Search for neutrinoless double-beta decays in Ge-76 in the LEGEND experiment
Get PDFThe search for neutrinoless double-beta decay is the most sensitive technique to establish the Majorana nature of neutrinos. Two operating experiments that look for such decays in Ge-76, Gerda and Majorana Demonstrator have achieved the lowest backgrounds and the best energy resolution in the signal region. These are two of the most important detector characteristics for sensitive searches of this undiscovered decay. The Large Enriched Germanium Experiment for Neutrinoless Double-Beta Decay (LEGEND) Collaboration has been formed to pursue a tonne-scale Ge-76 experiment that integrates the best technologies from these two experiments and others in the field. The Collaboration is developing a phased experimental program that uses existing resources as appropriate to expedite physics results, with the ultimate discovery potential at a decay half-life beyond 1028 years
Multiscale image analysis applied to γ/h discrimination for VHE gamma-ray astronomy with ARGO-YBJ
No full textIntrinsic differences in the processes involved in the electromagnetic and hadronic shower development in the atmosphere have been evidenced by means of a careful analysis of the event image given by the ARGO-YBJ detector. The images have been analyzed at different length scales and their multifractal nature has been studied. The use of the multiscale approach together with a properly designed and trained Artificial Neural Network, allowed us to obtain a good discrimination power. If confirmed by further studies on different event categories, this result would allow to nearly double the detector sensitivity to gamma-ray sources. © 2004 Elsevier B.V. All rights reserved
GERDA and LEGEND: Probing the Neutrino Nature and Mass at 100 meV and beyond
Get PDFThe Gerda (GERmanium Detector Array) project, located at Laboratori Nazionali del Gran Sasso (LNGS), was started in 2005, a few years after the claim of evidence for the neutrinoless double beta decay (0νββ) of 76Ge to the ground state of 76Se: it is an ultra-rare process whose detection would directly establish the Majorana nature of the neutrino and provide a measurement of its mass and mass hierarchy. The aim of Gerda was to confirm or disprove the claim by an increased sensitivity experiment. After establishing the new technology of Ge detectors operated bare in liquid Argon and since 2011, Gerda efficiently collected data searching for 0νββ of 76Ge, first deploying the 76Ge-enriched detectors from two former experiments and later new detectors with enhanced signal-to-background rejection, produced from freshly 76Ge-enriched material. Since then, the Gerda setup has been upgraded twice, first in 2013–2015 and later in 2018. The period before 2013 is Phase I and that after 2015 is Phase II. Both the Gerda setup and the analysis tools evolved along the project lifetime, allowing to achieve the remarkable average energy resolution of ∼3.6 and ∼2.6 keV for Coaxial Germanium (Coax) detectors and for Broad Energy Germanium (BEGe), respectively, and the background index of 5.2−1.3+1.6 · 10−4 cts/(keV·kg·yr) in a 230 keV net range centered at Qββ. No evidence of the 0νββ decay at Qββ = 2039.1 keV has been found, hence the limit of 1.8·1026 yr on the half-life (T1/20ν) at 90% C.L. was set with the exposure of 127.2 kg·yr. The corresponding limit range for the effective Majorana neutrino mass mee has been set to 79–180 meV. The Gerda performances in terms of background index, energy resolution and exposure are the best achieved so far by 76Ge double beta decay experiments. In Phase II, Gerda succeeded in operating in a background free regime and set a world record. In 2017, the Legend Collaboration was born from the merging of the Gerda and Majorana Collaborations and resources with the aim to further improve the Gerda sensitivity. First, the Legend200 project, with a mass of up to 200 kg of 76Ge-enriched detectors, aims to further improve the background index down to 10−3 cts/(keV·kg·yr) to explore the Inverted Hierarchy region of the neutrino mass ordering, then the Legend1000 (1 ton of 76Ge-enriched) will probe the Normal Hierarchy. In this paper, we describe the Gerda experiment, its evolution, the data analysis flow, a selection of its results and technological achievements, and finally the design, features and challenges of Legend, the Gerda prosecutor
Evolution of Br/Cl ratios in fumarolic salammoniac from Vulcano (Aeolian Islands, Italy)
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Searches for large-scale anisotropies of cosmic rays: Harmonic analysis and shuffling technique
No full textThe measurement of large scale anisotropies in cosmic ray arrival directions is generally performed through harmonic analyses of the right ascension distribution as a function of energy. These measurements are challenging due to the small expected anisotropies and meanwhile the relatively large modulations of observed counting rates due to experimental effects. In this paper, we present a procedure based on the shuffling technique to carry out these measurements, applicable to any cosmic ray detector without any additional corrections for the observed counting rates
Propagation of Ultra High Energy Cosmic Rays and the Production of Cosmogenic Neutrinos
No full textWe present an updated version of the SimProp Monte Carlo code to study the propagation of ultra high energy cosmic rays in astrophysical backgrounds computing the cosmogenic neutrino fluxes expected on earth. The study of secondary neutrinos provides a powerful tool to constrain the source models of these extremely energetic particles. We will show how the newly detected IceCube neutrino events at PeV energies together with the the latest experimental results of the Pierre Auger Observatory and Telescope Array experiment are almost at the level of excluding several hypothesis on the astrophysical sources of ultra high energy cosmic rays. Results presented here can be also used to evaluate the discovery capabilities of future high energy cosmic rays and neutrino detectors
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