48 research outputs found
Observation of complex time structures in the cosmic-ray electron and positron fluxes by the alpha magnetic spectrometer on the ISS
No full textWe present high-statistics, precision measurements by AMS of the detailed time and energy dependence of the primary cosmic-ray electron and positron uxes over 79 Bartels rotations from May 2011 to May 2017 in the energy range from 1 to 50 GeV. For the first time, the charge-sign dependent modulation during the solar maximum has been investigated in detail by leptons alone. We report the observation of short-term structures on the timescale of months which are not visible in the positron-to-electron ux ratio. The precision measurements across the solar polarity reversal show that the ratio exhibits a smooth transition over ∼800 days from one value to another
Development of a SiPM Cherenkov camera demonstrator for the CTA observatory telescopes
No full textThe Cherenkov Telescope Array (CTA) Consortium is developing the new generation of ground observatories for the detection of ultra-high energy gamma rays. The Italian Institute of Nuclear Physics (INFN) is participating to the R&D of a possible solution for the Cherenkov photon cameras based on Silicon Photomultipliers (SiPM) sensitive to UV energies. INFN is developing the concept, mechanics and electronics for SiPM prototype modules intended to equip the focal planes of CTA telescopes. The module design and performances are reviewed here
Precision Measurement of the Electron and Positron Fluxes in Primary Cosmic Rays with the Alpha Magnetic Spectrometer on the International Space Station
No full textIdentification of positrons and electrons in the cosmic radiation with the electromagnetic calorimeter ECAL for the AMS-02 experiment
No full textIn May 2011 AMS-02 detector has been successfully installed on the International
Space Station (ISS), where it will take data on cosmic radiation from 1 to 1000 GeV
for at least 10 years.
Among all scientific objectives of the experiment, one of the most important is
the search for Dark Matter (DM), which constitutes ∼ 80% of the Universe mass,
but its nature is still unknown. A DM signal can be identified by studying the
combined fluxes of positrons, photons, antiprotons and antideuterium. Thanks to
its high acceptance and its performances, AMS-02 detector can extend and expand
primary cosmic ray physics search to a new energy range with high accuracy.
A key role for these measurements, in particular for electromagnetic channels, is
played by ECAL calorimeter. This subdetector has been developed to measure γ, e−
and e+ energy with an accuracy of few %. Thanks to its 3D shower reconstruction
imaging capabilities, it also has a high separation power between electromagnetic and
hadronic showers (e/p rejection), essential to eliminate proton background (∼ 10^4 )
in positron channel. Finally, it provides the trigger on photons which do not interact in the upper part of the detector (about 72% of the ones in ECAL geometrical
acceptance).
In Chapter 1 of this thesis, cosmic ray physics is introduced with details on Big
Bang cosmology and the DM problem. Then, a summary of direct and in particular
indirect searches for DM signature is presented.
In Chapter 2 and 3 AMS-02 detector is presented with an overview of each subdetector features and performances. ECAL electromagnetic calorimeter is described
in detail.
Chapter 4 describes an in-flight calibration method, which has been developed
and tested on August 2010 Test Beam data, with its application performances on
ground and on in-flight data.
In Chapter 5, the calorimeter capabilities have been used to develop e± identification algorithms, using both ECAL standalone and also tracker momentum measurements. The definition of algorithms, training and testing processes, data-MC
comparisons and proton rejection spectrum are described
Measurement of the cosmic Flux from 0.5 GeV to 1 TeV with the Alpha Magnetic Spectrometer (AMS-02) on the International Space Station
No full textThe measurement of positrons and electrons (e+/-) in cosmic rays provides fundamental information about the origin and the propagation of cosmic rays in the Galaxy. The interest in the e measurements is enhanced by the possibility to observe indirect evidences of Dark Matter annihilation in the e spectral shapes and arrival directions. The most precise space experiment for the detection of cosmic rays is the Alpha Magnetic Spectrometer (AMS). AMS is a large acceptance cosmic ray detector which has been installed on the International Space Station in May 2011 to conduct an unique long-duration ( ~20 years) mission of fundamental physics research in space. In this thesis, the events collected by AMS in the first 30 months of data taking have been analyzed to measure the (e+ + e-) energy spectrum. A total of 10.6 million events have been identified as e+/- and have been used for the measurement of the (e+ + e-) flux from 0.5 GeV to 1 TeV. In this thesis the AMS detection capabilities, the e+/- identification procedure, the (e+ +e-) flux measurement, and the discussion of the result are presented
Advances in Space Astroparticle Physics: Frontier Technologies for Particle Measurements in Space
No full textIn the last decades, breakthrough advances in understanding the mechanisms of the Universe and fundamental physics have been achieved through the exploitation of data on cosmic rays and high-energy radiation gathered via orbiting experiments, in a synergic and complementary international effort that combines space-based instrument data with ground-based space observatories, accelerator, and collider experiments [...
The AMS-02 detector on the ISS - Status and highlights after 11 years on orbit
No full textThe Alpha Magnetic Spectrometer, AMS-02, is a magnetic spectrometer detector operating on the International Space Station (ISS) since May the 19, 2011. More than 200 billion events have been collected by the instrument in the first 11 years of data taking, providing detailed and novel insights on the composition and energy spectra of cosmic rays up to TeV energies. We review the most recent AMS-02 measurements and the advances in the understanding of cosmic ray origin, acceleration and propagation physics
Dynamic and on demand data streams
No full textReplicability and efficiency of data processing on the same data samples are a major challenge for the analysis of data produced by HEP experiments. High level data analyzed by end-users are typically produced as a subset of the whole experiment data sample to study interesting selection of data (streams). For standard applications, streams may be eventually copied from servers and analyzed on local computing centers or user machine clients. The creation of streams as copy of a subset of the original data results in redundant information stored in filesystems and may be not efficient: if the definition of streams changes, it may force a reprocessing of the low-level files with consequent impact on the data analysis efficiency. We propose an approach based on a database of lookup tables intended for dynamic and on-demand definition of data streams. This enables the end-users, as the data analysis strategy evolves, to explore different definitions of streams with minimal cost in computing resources. We also present a prototype demonstration application of this database for the analysis of the AMS-02 experiment data
The (e++e−) flux measurement up to 1 TeV with the AMS-02 experiment
No full textAbstractAMS-02 is a large acceptance cosmic ray detector operating on the International Space Station since May 2011. Of the ∼41 billion events collected in the first 30 months of data taking, 10.6 million have been selected as e+ and e− for the measurement of the (e++e−) energy spectrum from 0.5 GeV to 1 TeV. In this contribution, the latest result on the (e++e−) flux measurement with AMS is presented
