The Imaging X-ray Polarimetry Explorer is a mission dedicated to the measurement of X-ray polarization from tens of astrophysical sources belonging to different classes. Expected to be launched at ...the end of 2021, the payload comprises three mirrors and three focal plane imaging polarimeters, the latter being designed and built in Italy. While calibration is always an essential phase in the development of high-energy space missions, for IXPE it has been particularly extensive both to calibrate the response to polarization, which is peculiar to IXPE, and to achieve a statistical uncertainty below the expected sensitivity. In this paper we present the calibration equipment that was designed and built at INAF-IAPS in Rome, Italy, for the calibration of the polarization-sensitive focal plane detectors on-board IXPE. Equipment includes calibration sources, both polarized and unpolarized, stages to align and move the beam, test detectors and their mechanical assembly. While all these equipments were designed to fit the specific needs of the IXPE Instrument calibration, their versatility could also be used in the future for other projects.
AGILE, the Italian space mission dedicated to gamma-ray and hard-X astrophysics, was succesfully launched on 23 April 2007 and is currently fully operative. AGILE is placed in an equatorial Low-Earth ...Orbit, at 550 km altitude with 2.46 degrees inclination. The Mini-Calorimeter (MCAL) on-board AGILE is a scintillation detector made of 30 CsI(Tl) bars with photodiode readout at both ends, arranged in two orthogonal layers, for a total amount of 20 kg of active material, an on-axis geometrical area of 1400 cm 2 and a thickness of 1.5 radiation lengths. MCAL can work both as a slave of the AGILE Silicon tracker and as an independent detector for gamma-ray burst (GRB) detection in the 300 keV - 200 MeV energy range. If a trigger is issued by a dedicated onboard logic, data are dowloaded in photon-by-photon mode with a time resolution of 2σs allowing complete spectral and timing analysis of the event, limited by counting statistics only. Moreover, 11 band energy spectra with 1 second time resolution (scientific ratemeters) are continuously integrated on-board and sent to telemetry for background monitoring. MCAL is currently one of the three detectors in space with microsecond timing accuracy in the MeV range, with a detection rate of 1 GRB/week. The performance of the instrument after 18 months of in orbit operations will be discussed, as well as the scientific results achieved.
THESEUS is one of the three missions selected by ESA as fifth medium class mission (M5) candidates in its Cosmic Vision science program, currently under assessment in a phase A study with a planned ...launch date in 2032. THESEUS is designed to carry on-board two wide and deep sky monitoring instruments for X/gamma-ray transients detection: a wide-field soft X-ray monitor with imaging capability (Soft X-ray Imager, SXI, 0.3 - 5 keV), a hard X-ray, partially-imaging spectroscopic instrument (X and Gamma Imaging Spectrometer, XGIS, 2 keV - 10 MeV), and an optical/near-IR telescope with both imaging and spectroscopic capability (InfraRed Telescope, IRT, 0.7 - 1.8 \(\mu\)m). The spacecraft will be capable of performing fast repointing of the IRT to the error region provided by the monitors, thus allowing it to detect and localize the transient sources down to a few arcsec accuracy, for immediate identification and redshift determination. The prime goal of the XGIS will be to detect transient sources, with monitoring timescales down to milliseconds, both independently of, or following, up SXI detections, and identify the sources performing localisation at < 15 arcmin and characterize them over a broad energy band, thus providing also unique clues to their emission physics. The XGIS system consists of two independent but identical coded mask cameras, arranged to cover 2 steradians . The XGIS will exploit an innovative technology coupling Silicon Drift Detectors (SDD) with crystal scintillator bars and a very low-noise distributed front-end electronics (ORION ASICs), which will produce a position sensitive detection plane, with a large effective area over a huge energy band (from soft X-rays to soft gamma-rays) with timing resolution down to a few \(\mu\)s.Here is presented an overview of the XGIS instrument design, its configuration, and capabilities.
Supernova Remnants (SNRs) exhibit spectra featured by synchrotron radio emission arising from the relativistic electrons, and high-energy emission from both leptonic (Bremsstrahlung and Inverse ...Compton) and hadronic processes (\({\pi}^0\) mesons decay) which are a direct signature of cosmic rays acceleration. Thanks to radio single-dish imaging observations obtained in three frequency bands (1.6, 7, 22 GHz) with the Sardinia Radio Telescope (www.srt.inaf.it), we can model different SNR regions separately. Indeed, in order to disentangle interesting and peculiar hadron contributions in the high-energy spectra (gamma-ray band) and better constrain SNRs as cosmic rays emitters, it is crucial to fully constrain lepton contributions first through radio-observed parameters. In particular, the Bremsstrahlung and Inverse Compton bumps observed in gamma-rays are bounded to synchrotron spectral slope and cut-off in the radio domain. Since these parameters vary for different SNR regions and electron populations, spatially-resolved radio spectra are then required for accurate multi-wavelength modelling.
The energy range between 10 and 50 MeV is an experimentally very difficult range and remained uncovered since the time of COMPTEL. Here we propose a possible mission to cover this energy range.
High-energy phenomena in the cosmos, and in particular processes leading to the emission of gamma- rays in the energy range 10 MeV - 100 GeV, play a very special role in the understanding of our ...Universe. This energy range is indeed associated with non-thermal phenomena and challenging particle acceleration processes. The technology involved in detecting gamma-rays is challenging and drives our ability to develop improved instruments for a large variety of applications. GAMMA-LIGHT is a Small Mission which aims at an unprecedented advance of our knowledge in many sectors of astrophysical and Earth studies research. The Mission will open a new observational window in the low-energy gamma-ray range 10-50 MeV, and is configured to make substantial advances compared with the previous and current gamma-ray experiments (AGILE and Fermi). The improvement is based on an exquisite angular resolution achieved by GAMMA-LIGHT using state-of-the-art Silicon technology with innovative data acquisition. GAMMA-LIGHT will address all astrophysics issues left open by the current generation of instruments. In particular, the breakthrough angular resolution in the energy range 100 MeV - 1 GeV is crucial to resolve patchy and complex features of diffuse sources in the Galaxy as well as increasing the point source sensitivity. This proposal addresses scientific topics of great interest to the community, with particular emphasis on multifrequency correlation studies involving radio, optical, IR, X-ray, soft gamma-ray and TeV emission. At the end of this decade several new observatories will be operational including LOFAR, SKA, ALMA, HAWK, CTA. GAMMA-LIGHT will "fill the vacuum" in the 10 MeV-10 GeV band, and will provide invaluable data for the understanding of cosmic and terrestrial high-energy sources.
Since the birth of X-ray astronomy, spectral, spatial and timing observation improved dramatically, procuring a wealth of information on the majority of the classes of the celestial sources. ...Polarimetry, instead, remained basically unprobed. X-ray polarimetry promises to provide additional information procuring two new observable quantities, the degree and the angle of polarization. POLARIX is a mission dedicated to X-ray polarimetry. It exploits the polarimetric response of a Gas Pixel Detector, combined with position sensitivity, that, at the focus of a telescope, results in a huge increase of sensitivity. Three Gas Pixel Detectors are coupled with three X-ray optics which are the heritage of JET-X mission. POLARIX will measure time resolved X-ray polarization with an angular resolution of about 20 arcsec in a field of view of 15 arcmin \(\times\) 15 arcmin and with an energy resolution of 20 % at 6 keV. The Minimum Detectable Polarization is 12 % for a source having a flux of 1 mCrab and 10^5 s of observing time. The satellite will be placed in an equatorial orbit of 505 km of altitude by a Vega launcher.The telemetry down-link station will be Malindi. The pointing of POLARIX satellite will be gyroless and it will perform a double pointing during the earth occultation of one source, so maximizing the scientific return. POLARIX data are for 75 % open to the community while 25 % + SVP (Science Verification Phase, 1 month of operation) is dedicated to a core program activity open to the contribution of associated scientists. The planned duration of the mission is one year plus three months of commissioning and SVP, suitable to perform most of the basic science within the reach of this instrument.
The SuperAGILE experiment is the hard X-ray monitor of the Italian AGILE gamma-ray mission. SuperAGILE is the first experiment for X-ray astronomy employing single-sided silicon microstrip detectors ...in space. The fine position sensitivity of these detectors allowed to design a coded mask imaging experiment very compact and resource-effective, operating in the 18-60 keV energy range. In this paper we present the design of the experiment, its development as well as its first operations in orbit, and a brief summary of the main scientific results achieved after 12 months of nominal observations.
This study aimed to define the optimum weight ratio between Berea Red sand (BRS)/zero-valent iron (ZVI) combinations to be used in the treatment of nitrate contaminated water. The effect of competing ...ions (phosphate and sulfate) on the nitrate removal efficiency of the best performing BRS-ZVI w/w ratio was also assessed. To achieve this objective, batch tests were performed under anoxic and acidic conditions (pH
i
= 4.5), using two combinations: 50%BRS-50%ZVI (w/w) and 25%BRS-75%ZVI (w/w), as well as 100%ZVI as a control. BRS and ZVI had 1 to 2-mm grain size. pH and nitrogen species were tested during these batch tests. Kinetic analysis was also carried out. While the removal efficiencies of 100%ZVI and 25%BRS-75%ZVI (w/w) were 70.2% and 83.1%, respectively, the experimental results showed that the combination of 50%BRS-50%ZVI (w/w) had the highest nitrate removal efficiency (99.5%), implying a synergistic effect between BRS and ZVI. Likewise, the kinetic analysis showed that the nitrate removal rate (k) increased as the BRS mass in the BRS-ZVI combination increased. Furthermore, the presence of phosphate and sulfate negatively affected the nitrate removal performance of the 50%BRS-50%ZVI combination, which was the best performing weight ratio. However, this weight ratio still showed high nitrate removal capacities in the presence of phosphate and sulfate, respectively. The 50%BRS-50%ZVI combination demonstrated to be the optimum among the used ones. However, further investigation in a large-scale reactor on this combination is recommended for further optimization of its performance.
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