Engineering topics

Boezio, M.

Publications and source records attributed to Boezio, M..

9 records

NASA NTRS2019

Comparing Long-Duration Gamma-Ray Flares and High-Energy Solar Energetic Particles

Little is known about the origin of the high-energy and sustained emission from solar long-duration gamma-ray ﬂares (LDGRFs) identiﬁed with the Compton Gamma Ray Observatory, the Solar Maximum Mission, and now Fermi. Though the Fermi Large Area Telescope (LAT) has identiﬁed dozens of ﬂares with LDGRF signatures, the nature of this phenomenon has been a challenge to explain due to both extreme energies and long durations. The highest-energy emission has generally been attributed to pion production from the interaction of 300 MeV protons with the ambient matter. The extended duration suggests that particle acceleration occurs over large volumes extending high in the corona, either from stochastic acceleration within large coronal loops or from back precipitation from coronal mass ejection–driven shocks. It is possible to test these models by making a direct comparison between the properties of the accelerated ion population producing the γ-ray emission derived from the Fermi/LAT observations and the characteristics of solar energetic particles (SEPs) measured by the Payload for Matter-Antimatter Exploration and Light Nuclei Astrophysics spacecraft in the energy range corresponding to the pion-related emission detected with Fermi. For 14 of these events, we compare the two populations—SEPs in space and the interacting particles at the Sun—and discuss the implications in terms of potential sources. Our analysis shows that the two proton numbers are poorly correlated, with their ratio spanning more than 5 orders of magnitude, suggesting that the back precipitation of shock-acceleration particles is unlikely to be the source of the F emission.

Nolfo, G. A. de↗

NASA NTRS2018

Solar Energetic Particle Events Observed by the PAMELA Mission

Despite the significant progress achieved in recent years, the physical mechanisms underlying the origin of solar energetic particles (SEPs) are still a matter of debate. The complex nature of both particle acceleration and transport poses challenges to developing a universal picture of SEP events that encompasses both the low-energy (from tens of keV to a few hundreds of MeV)observations made by space-based instruments and the GeV particles detected by the worldwide network of neutron monitors in ground-level enhancements (GLEs). The high-precision data collected by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) satellite experiment offer a unique opportunity to study the SEP fluxes between ∼80 MeV and a few GeV, significantly improving the characterization of the most energetic events. In particular, PAMELA can measure for the first time with good accuracy the spectral features at moderate and high energies, providing important constraints for current SEP models. In addition, the PAMELA observations allow the relationship between low and high-energy particles to be investigated, enabling a clearer view of the SEP origin. No qualitative distinction between the spectral shapes of GLE, sub-GLE and non-GLE events is observed, suggesting that GLEs are not a separate class, but are the subset of a continuous distribution of SEP events that are more intense at high energies. While the spectral forms found are to be consistent with diffusive shock acceleration theory, which predicts spectral rollovers at high energies that are attributed to particles escaping the shock region during acceleration, further work is required to explore the relative influences of acceleration and transport processes on SEP spectra.

Bruno, A.↗

NASA NTRS2016

The May 17, 2012 Solar Event: Back-Tracing Analysis and Flux Reconstruction with PAMELA

The PAMELA space experiment is providing first direct observations of Solar Energetic Particles (SEPs) with energies from about 80 MeV to several GeV in near-Earth orbit, bridging the low energy measurements by other spacecrafts and the Ground Level Enhancement (GLE) data by the worldwide network of neutron monitors. Its unique observational capabilities include the possibility of measuring the flux angular distribution and thus investigating possible anisotropies associated to SEP events. The analysis is supported by an accurate back-tracing simulation based on a realistic description of the Earth's magnetosphere, which is exploited to estimate the SEP energy spectra as a function of the asymptotic direction of arrival with respect to the Interplanetary Magnetic Field (IMF). In this work we report the results for the May 17, 2012 event.

Bruno, A.↗

NASA NTRS2013

Analysis on H Spectral Shape During the Early 2012 SEPs with the PAMELA Experiment

The satellite-borne PAMELA experiment has been continuously collecting data since 2006.This apparatus is designed to study charged particles in the cosmic radiation. The combination of a permanent magnet, a silicon strip tracker and a silicon-tungsten imaging calorimeter, and the redundancy of instrumentation allow very precise studies on the physics of cosmic rays in a wide energy range and with high statistics. This makes PAMELA a very suitable instrument for Solar Energetic Particle (SEP) observations. Not only does its pan the energy range between the ground-based neutron monitor data and the observations of SEPs from space,but PAMELA also carries out the first direct measurements of the composition for the highest energy SEP events, including those causing Ground Level Enhancements (GLEs).In particular, PAMELA has registered many SEP events during solar cycle 24,offering unique opportunities to address the question of high-energy SEP origin. A preliminary analysis on proton spectra behaviour during this event is presented in this work.

Protons↗

NASA NTRS2013

PAMELA Observation of the 2012 May 17 GLE Event

The PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) satellite-borne experiment has been collecting data in orbit since July 2006, providing accurate measurements of the energy spectra and composition of the cosmic radiation from a few hundred MeVn up to hundred GeVn. This wide interval of measured energies makes PAMELA a unique instrument for Solar Energetic Particle (SEP) observations. Not only does it span the energy range between the ground-based neutron monitor data and the observations of SEPs from space, but also PAMELA carries out the first direct measurements of the composition for the highest energy SEP events, including those causing Ground Level Enhancements (GLEs). PAMELA has registered many SEP events in solar cycle 24 including the 2012 May 17 GLE event (GLE 71), offering unique opportunities to address the question of high-energy SEP origin. Experimental performances and preliminary results on the 2012 May 17 events will be presented. We will discuss the derived particle injection time and compare with other time scales at the Sun including the flare and CME onset times.

Solar Flares↗

NASA NTRS2013

Study on 2012 March 7 Solar Particle Event and Forbush Decrease with the PAMELA Experiment

The PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astro-physics) spaceborne experiment was launched on 15 June 2006 and has been continuously collecting data since then. The apparatus measures electrons, positrons, protons, anti-protons and heavier nuclei from about 100 megaelectronvolts to several hundreds of gigaelectronvolts. The on-board instrumentation is built around a permanent magnet with a silicon microstrip tracker, providing charge and track detection information. During solar maximum conditions of solar cycle 24, PAMELA has been providing key information about solar energetic particles (SEPs) and their influence at Earth. We discuss here the recent 2012 March 7 SEP event with a brief comment on the subsequent Forbush decrease, registered by PAMELA. This event was also observed by Fermi/LAT (Large Area Telescope) exhibiting unprecedented time-extended gamma-ray emission (greater than 100 megaelectronvolts) lasting nearly 20 hours. We compare the derived accelerated ion population at the Sun with the ion population measured in space by PAMELA and discuss the implications for particle acceleration.

Forbush Decrease↗

NASA NTRS2013

Status of the GAMMA-400 Project

The preliminary design of the new space gamma-ray telescope GAMMA-400 for the energy range 100 MeV-3 TeV is presented. The angular resolution of the instrument, 1-2 deg at E(gamma) approximately 100 MeV and approximately 0.01 at E(gamma) greater than 100 GeV, its energy resolution is approximately 1% at E(gamma) greater than 100 GeV, and the proton rejection factor is approximately 10(exp 6) are optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high-precision measurements of spectra of cosmic-ray electrons, positrons, and nuclei.

Galper, A. M.↗

NASA NTRS2012

Design and Performance of the GAMMA-400 Gamma-Ray Telescope for Dark Matter Searches

The GAMMA-400 gamma-ray telescope is designed to measure the fluxes of gamma-rays and cosmic-ray electrons + positrons, which can be produced by annihilation or decay of the dark matter particles, as well as to survey the celestial sphere in order to study point and extended sources of gamma-rays, measure energy spectra of Galactic and extragalactic diffuse gamma-ray emission, gamma-ray bursts, and gamma-ray emission from the Sun. GAMMA-400 covers the energy range from 100 MeV to 3000 GeV. Its angular resolution is approx. 0.01 deg (E(sub gamma) > 100 GeV), the energy resolution approx. 1% (E(sub gamma) > 10 GeV), and the proton rejection factor approx 10(exp 6). GAMMA-400 will be installed on the Russian space platform Navigator. The beginning of observations is planned for 2018.

Dark Matter↗

NASA NTRS2012

Design and Performance of the GAMMA-400 Gamma-Ray Telescope for Dark Matter Searches

The GAMMA-400 gamma-ray telescope is designed to measure the fluxes of gamma-rays and cosmic-ray electrons (+) positrons, which can be produced by annihilation or decay of the dark matter particles, as well as to survey the celestial sphere in order to study point and extended sources of gamma-rays, measure energy spectra of Galactic and extragalactic diffuse gamma-ray emission, gamma-ray bursts, and gamma-ray emission from the Sun. GAMMA-400 covers the energy range from 100 MeV to 3000 GeV. Its angular resolution is approximately 0.01deg (E(sub gamma) greater than 100 GeV), the energy resolution approximately 1% (E(sub gamma) greater than 10 GeV), and the proton rejection factor approximately 10(exp 6). GAMMA-400 will be installed on the Russian space platform Navigator. The beginning of observations is planned for 2018.

Dark Matter↗