The DArk Matter Particle Explorer (DAMPE) is a space-based particle detector launched in a sun-synchronous orbit on December 17, 2015 from the Jiuquan Satellite Launch Center, in China. The main ...goals of the DAMPE mission include the study of the electron–positron energy spectrum, the study of galactic cosmic rays, gamma-ray astronomy, and indirect dark matter searches. Among its subdetectors, the deep BGO calorimeter makes DAMPE able to measure the cosmic-ray electrons and positrons (CRE) spectrum up to 10 TeV and cosmic-ray nuclei (CR) spectra up to 100 TeV, with unprecedented energy resolution. This high-energy region is important in order to search for possible nearby CRE sources, for dark matter signatures, and to have a better understanding of CR acceleration and propagation mechanisms inside the Galaxy. A break at about 1 TeV was clearly evidenced by DAMPE in the CRE energy spectrum. Moreover, DAMPE precise measurements of CR protons and helium spectra, confirmed the hardening at few hundreds GeV
and revealed a spectral softening at about 14 and 30 TeV for
and He, respectively, suggesting a rigidity dependent mechanism. About 250 gamma ray sources were detected and identified. Spectral analyses on medium and heavy mass nuclei are currently ongoing. The main results of the mission will be presented, along with ongoing activities.
The NUSES space mission De Mitri, I.; Di Santo, M.
Journal of physics. Conference series,
02/2023, Volume:
2429, Issue:
1
Journal Article
Peer reviewed
Open access
Abstract
NUSES is a new space mission aiming to test innovative observational and technological approaches related to the study of low energy cosmic and gamma rays, high energy astrophysical ...neutrinos, Sun-Earth environment, Space weather and magnetosphere-ionosphere-lithosphere coupling (MILC). The satellite will host two payloads, named TERZINA and ZIRÉ. ZIRÉ will perform measurements of electrons, protons and light nuclei from few up to hundreds of MeV, also testing new tools for the detection of cosmic MeV photons, and monitoring of MILC signals. TERZINA will observe the Cherenkov light produced by EAS generated by cosmic ray primaries at very high energies and will monitor the light emissions from the Earth limb in the near UV and visible ranges at the ns time scale, thus testing the observational concept of detecting Earth skimming astrophysical high energy neutrinos. The scientific objectives and development status of the mission will be presented.
ABSTRACT We report on the extensive multi-wavelength observations of the blazar Markarian 421 (Mrk 421) covering radio to γ-rays, during the 4.5 year period of ARGO-YBJ and Fermi common operation ...time, from 2008 August to 2013 February. These long-term observations, extending over an energy range of 18 orders of magnitude, provide a unique chance to study the variable emission of Mrk 421. In particular, due to the ARGO-YBJ and Fermi data, the entire energy range from 100 MeV to 10 TeV is covered without any gap. In the observation period, Mrk 421 showed both low- and high-activity states at all wavebands. The correlations among flux variations in different wavebands were analyzed. The X-ray flux is clearly correlated with the TeV γ-ray flux, while the GeV γ-rays only show a partial correlation with the TeV γ-rays. Radio and UV fluxes seem to be weakly or not correlated with the X-ray and γ-ray fluxes. Seven large flares, including five X-ray flares and two GeV γ-ray flares with variable durations (3-58 days), and one X-ray outburst phase were identified and used to investigate the variation of the spectral energy distribution with respect to a relative quiescent phase. During the outburst phase and the seven flaring episodes, the peak energy in X-rays is observed to increase from sub-keV to a few keV. The TeV γ-ray flux increases up to 0.9-7.2 times the flux of the Crab Nebula. The behavior of GeV γ-rays is found to vary depending on the flare, a feature that leads us to classify flares into three groups according to the GeV flux variation. Finally, the one-zone synchrotron self-Compton model was adopted to describe the emission spectra. Two out of three groups can be satisfactorily described using injected electrons with a power-law spectral index around 2.2, as expected from relativistic diffuse shock acceleration, whereas the remaining group requires a harder injected spectrum. The underlying physical mechanisms responsible for different groups may be related to the acceleration process or to the environment properties.
The ARGO-YBJ detector, located at high altitude in the Cosmic Ray Observatory of YangBaJing in Tibet (4300 m asl, about 600 g/cm2 of atmospheric depth) provides the opportunity for the study, with ...unprecedented resolution, of cosmic ray physics in the primary energy region between 1012 and 1016 eV. Preliminary results of the measurements of the all-particle and light-component (i.e. protons and helium) energy spectra between approximately 5 TeV and 5 PeV are reported and discussed.
A computer-aided detection (CAD) system for the selection of lung nodules in computer tomography (CT) images is presented. The system is based on region growing (RG) algorithms and a new active ...contour model (ACM), implementing a local convex hull, able to draw the correct contour of the lung parenchyma and to include the pleural nodules. The CAD consists of three steps: (1) the lung parenchymal volume is segmented by means of a RG algorithm; the pleural nodules are included through the new ACM technique; (2) a RG algorithm is iteratively applied to the previously segmented volume in order to detect the candidate nodules; (3) a double-threshold cut and a neural network are applied to reduce the false positives (FPs). After having set the parameters on a clinical CT, the system works on whole scans, without the need for any manual selection. The CT database was recorded at the Pisa center of the ITALUNG-CT trial, the first Italian randomized controlled trial for the screening of the lung cancer. The detection rate of the system is
88.5
%
with 6.6 FPs/CT on 15 CT scans (about 4700 sectional images) with 26 nodules: 15 internal and 11 pleural. A reduction to 2.47 FPs/CT is achieved at
80
%
efficiency.
Abstract
Crystal Eye idea comes from the analysis of two gravitational waves events: GW170817 and GW190425. Both events were referred to neutron star mergers. In the first case Fermi-GBM and INTEGRAL ...claimed the detection of a short Gamma Ray Burst (GRB 170817A) and in order to follow up and target the GW electromagnetic counterparts, a huge effort has been made by other satellites and ground-based experiments. In the second case, only INTEGRAL claimed the detection of a faint GRB (GRB 190425) while Fermi satellite was in Earth occultation. Crystal Eye is a space-based X and γ ray all-sky monitor sensitive in the 10 keV - 30 MeV energy range. In its baseline configuration, it consists of a hemisphere, made by 112 pixels, with a wide (about 6 sr) field of view (FOV), a full sky coverage and a very large effective area (6 times Fermi-GBM at 1 MeV) in the energy range of interest. Given the pixel structure – a two-layer crystal scintillator and a plastic scintillator veto layer – and the hemispherical design, Crystal Eye concentrate the pointing capability of a γ-ray telescope and the sky coverage of an all-sky monitor in a single detector. Moreover, the use of Silicon Photomultiplier (SiPM) at the place of traditional PMs, besides being a challenge for their qualification for space missions, allows a more compact and less power-consuming design. A Crystal Eye pathfinder has been designed and realized to be tested in view of the mission on the Space Rider by ESA. The prototype is made by 4 pixels. The mission is aimed at testing in the space environment the LYSO crystals, the MPPC-arrays and the DAQ board.
Plastic scintillators are widely used for anti-coincidence systems and for the identification of charged cosmic-ray nuclei in satellite experiments. For this reason, a plastic scintillator detector ...(PSD) should have a high detection efficiency for charged cosmic rays and a very good capability of measuring charges. We implemented a full and customizable simulation tool to investigate the performance of a PSD coupled to Silicon Photomultipliers. The overall performance of the detector is studied by tracking optical photons produced inside the scintillator. The simulation will be used for the design of a PSD for future space experiments, such as HERD, AMEGO, e-Astrogam. In this work we investigated in detail the effect of Birks’ saturation in the discrimination of charged ions up to iron nuclei. We will show the comparison between simulations and measurements conducted on prototype scintillator tiles.
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