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Register a new userInitial Results from the High Energy Experiment PDS aboard BeppoSAX
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The high energy experiment PDS is one of the Narrow Field Instruments aboard the X-ray astronomy satellite BeppoSAX. It covers the energy band from 15 to 300 keV. Here we report results on its in-flight performance and observations of galactic and extragalactic X-ray sources obtained during the Science Verification Phase of the satellite: in particular Crab, Cen X-3, 4U1626-67 and PKS2155-305.
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We review all the BeppoSAX results relative to the search for additional nonthermal components in the spectra of clusters of galaxies. In particular, our MECS data analysis of A2199 does not confirm the presence of the nonthermal excess reported by Kaastra et al. (1999). A new observation of A2256 seems to indicate quite definitely that the nonthermal fluxes detected in Coma and A2256 are due to a diffuse nonthermal mechanism involving the intracluster medium. We report marginal evidence (~3sigma) for a nonthermal excess in A754 and A119, but the presence of point sources in the field of view of the PDS makes unlikely a diffuse interpretation.
High resolution spectra of the active binary Capella (G8 III + G1 III) covering the energy range 0.4-8.0 keV (1.5-30 Angstroms) show a large number of emission lines, demonstrating the performance of the HETGS. A preliminary application of plasma diagnostics provides information on coronal temperatures and densities. Lines arising from different elements in a range of ionization states indicate that Capella has plasma with a broad range of temperatures, from log T = 6.3 to 7.2, generally consistent with recent results from observations with the Extreme Ultraviolet Explorer (EUVE) and the Advanced Satellite for Cosmology and Astrophysics (ASCA). The electron density is determined from He-like O VII lines, giving the value N_e=10^10 cm^-3 at T_e=2*10^6 K; He-like lines formed at higher temperatures give only upper limits to the electron density. The density and emission measure from O VII lines together indicate that the coronal loops are significantly smaller than the stellar radius.
In this contribution we discuss briefly a few calibration items relevant to the data analysis and present some preliminary scientific results. The discussion on instrumental topics focuses on the response matrix and Point Spread Function (PSF). In the scientific results section we discuss a first analysis of the two Seyferts MCG 6-30-15 and NGC 4151 and of the Cosmic X-ray Background.
Neutrinoless double-beta decay searches play a major role in determining the nature of neutrinos, the existence of a lepton violating process, and the effective Majorana neutrino mass. The MAJORANA Collaboration assembled an array of high purity Ge detectors to search for neutrinoless double-beta decay in Ge-76. The MAJORANA DEMONSTRATOR is comprised of 44.1 kg (29.7 kg enriched in Ge-76) of Ge detectors divided between two modules contained in a low-background shield at the Sanford Underground Research Facility in Lead, South Dakota, USA. The initial goals of the DEMONSTRATOR are to establish the required background and scalability of a Ge-based next-generation ton-scale experiment. Following a commissioning run that started in 2015, the first detector module started low-background data production in early 2016. The second detector module was added in August 2016 to begin operation of the entire array. We discuss results of the initial physics runs, as well as the status and physics reach of the full MAJORANA DEMONSTRATOR experiment.
The Extreme Energy Events (EEE) experiment is the largest system in the world completely implemented with Multigap Resistive Plate Chambers (MRPCs). Presently, it consists of a network of 59 muon telescopes, each made of 3 MRPCs, devoted to the study of secondary cosmic rays. Its stations, sometimes hundreds of kilometers apart, are synchronized at a few nanoseconds level via a clock signal delivered by the Global Positioning System. The data collected during centrally coordinated runs are sent to INFN CNAF, the largest center for scientific computing in Italy, where they are reconstructed and made available for analysis. Thanks to the on-line monitoring and data transmission, EEE operates as a single coordinated system spread over an area of about $3 times 10^5$ km$^2$. In 2017, the EEE collaboration started an important upgrade program, aiming to extend the network with 20 additional stations, with the option to have more in the future. This implies the construction, testing and commissioning of 60 chambers, for a total detector surface of around 80 m$^2$. In this paper, aspects related to this challenging endeavor are covered, starting from the technological solutions chosen to build these state-of-the-art detectors, to the quality controls and the performance tests carried on.
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