Ettore Del Monte

Detection of terrestrial gamma ray flashes up to 40 MeV by the AGILE satellite

We report the detection by the Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite of terrestrial gamma ray flashes (TGFs) obtained with the minicalorimeter (MCAL) detector operating in the ...

Gamma-Light: High-Energy Astrophysics above 10 MeV

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.

The AGILE Instrument

AGILE is an ASI gamma-ray astrophysics space Mission which will operate in the 30 MeV - 50 GeV range with imaging capabilities also in the 10 - 40 keV range. Primary scientific goals include the study of AGNs, gamma-ray bursts, Galactic sources, unidentified gamma-ray sources, diffuse Galactic and extragalactic gamma-ray emission, high-precision timing studies, and Quantum Gravity testing. The AGILE scientific instrument is based on an innovative design of three detecting systems: (1) a Silicon Tracker, (2) a Mini-Calorimeter, and (3) an ultralight coded mask system with Si-detectors (Super-AGILE). AGILE is designed to provide: (1) excellent imaging in the energy bands 30 MeV-50 GeV (5-10 arcmin for intense sources) and 10-40 keV (1-3 arcmin); (2) optimal timing capabilities, with independent readout systems and minimal deadtimes for the Silicon Tracker, Super-AGILE and Mini-Calorimeter; (3) large field of view for the gamma-ray imaging detector (~3 sr) and Super-AGILE (~1 sr). AGILE will be the only Mission entirely dedicated to source detection above 30 MeV during the period 2004-2006.

A set of x-ray polarimeters for the New Hard X-ray Imaging and Polarimetric Mission

The New Hard X-Ray Imaging and Polarimetric Mission makes a synergic use of Hard X-Ray Imaging, Spectroscopy and Polarimetry, as independent diagnostic of the same physical systems. It exploits the technology of multi-layer optics that, with a focal length of 10 m, allow for spectroscopic and imaging, with a resolution from 15 to 20 arcseconds, on the band 0.2 - 80 keV. One of the four telescopes is devoted to polarimetry. Since the band of a photoelectric polarimeter is not that wide, we foresee two of them, one tuned on the lower energy band (2-10 keV) and another one tuned on higher energies (6 - 35 keV). The blurring due to the inclined penetration of photons in the gas , thanks to the long focal length is practically negligible. In practice the polarimeters fully exploit the resolution the telescope and NHXM can perform angular resolved simultaneous spectroscopy and polarimetry on the band 2 - 35 keV. We are also studying the possibility to extend the band up to 80 keV by means of a focal plane scattering polarimeter.

Monitoring the hard X-ray sky with SuperAGILE

Context SuperAGILE is the hard X-ray monitor of the AGILE gamma ray mission, in orbit since 23 April 2007. It is an imaging experiment based on a set of four independent silicon strip detectors, eq ...

Scientific performances of the XAA1.2 front-end chip for silicon microstrip detectors

The XAA1.2 is a custom ASIC chip for silicon microstrip detectors adapted by Ideas for the SuperAGILE instrument on board the AGILE space mission. The chip is equipped with 128 input channels, each one containing a charge preamplifier, shaper, peak detector and stretcher. The most important features of the ASIC are the extended linearity, low noise and low power consumption. The XAA1.2 underwent extensive laboratory testing in order to study its commandability and functionality and evaluate its scientific performances. In this paper we describe the XAA1.2 features, report the laboratory measurements and discuss the results emphasizing the scientific performances in the context of the SuperAGILE front-end electronics.

A setup for soft proton irradiation of X-ray detectors for future astronomical space missions

Abstract Protons that are trapped in the Earths magnetic field are one of the main threats to astronomical X-ray observatories. Soft protons, in the range from tens of keV up to a few MeV, impinging on silicon X-ray detectors can lead to a significant degradation of the detector performance. Especially in low earth orbits an enhancement of the soft proton flux has been found. A setup to irradiate detectors with soft protons has been constructed at the Van-de-Graaff accelerator of the Physikalisches Institut of the University of Tubingen. Key advantages are a high flux uniformity over a large area, to enable irradiations of large detectors, and a monitoring system for the applied fluence, the beam uniformity, and the spectrum, that allows testing of detector prototypes in early development phases, when readout electronics are not yet available. Two irradiation campaigns have been performed so far with this setup. The irradiated detectors are silicon drift detectors, designated for the use on-board the LOFT space mission. This paper gives a description of the experimental setup and the associated monitoring system.

Background simulations for the Large Area Detector onboard LOFT

The Large Observatory For X-ray Timing (LOFT), currently in an assessment phase in the framework the ESA M3 Cosmic Vision programme, is an innovative medium-class mission specifically designed to answer fundamental questions about the behaviour of matter, in the very strong gravitational and magnetic fields around compact objects and in supranuclear density conditions. Having an effective area of ∼10 m2 at 8 keV, LOFT will be able to measure with high sensitivity very fast variability in the X-ray fluxes and spectra. A good knowledge of the in-orbit background environment is essential to assess the scientific performance of the mission and optimize the design of its main instrument, the Large Area Detector (LAD). In this paper the results of an extensive Geant-4 simulation of the instrumentwillbe discussed, showing the main contributions to the background and the design solutions for its reduction and control. Our results show that the current LOFT/LAD design is expected to meet its scientific requirement of a background rate equivalent to 10 mCrab in 2‒30 keV, achieving about 5 mCrab in the most important 2–10 keV energy band. Moreover, simulations show an anticipated modulation of the background rate as small as 10 % over the orbital timescale. The intrinsic photonic origin of the largest background component also allows for an efficient modelling, supported by an in-flight active monitoring, allowing to predict systematic residuals significantly better than the requirement of 1 %, and actually meeting the 0.25 % science goal.

Performance of the Gas Pixel Detector: an x-ray imaging polarimeter for upcoming missions of astrophysics

X-ray polarimetry is a hot topic and, as a matter of fact, a number of missions dedicated to the measurement of the polarization in the ∼2-8 keV energy range with photoelectric devices are under advanced study by space agencies. The Gas Pixel Detector (GPD), developed and continuously improved in Italy by Pisa INFN in collaboration with INAF-IAPS, is the only instrument able to perform imaging polarimetry; moreover, it can measure photon energy and time of arrival. In this paper, we report on the performance of a GPD prototype assembled with flight-like materials and procedures. The remarkably uniform operation over a long period of time assures a straightforward operation in orbit and support the high readiness level claimed for this instrument.

Instrumental and astrophysical performances of SuperAGILE on-board AGILE Gamma-Ray mission

SuperAGILE is the X-ray stage of AGILE gamma-ray mission. It is devoted to monitor X-ray (10 - 40 keV) sources with a sensitivity better than 10 mCrab in one observing day and to detect X-ray transients in a field of view of 1.8 sr, well matched to that of the gamma ray tracker, with few arc-minutes position resolution. SuperAGILE is designed to exploit one additional layer of four silicon micro-strip detectors, for 1444 cm2 of total geometrical area, on top of the AGILE tracker and a system of four mutually orthogonal one- dimensional coded masks to encode the X-ray sky. Low noise electronics based on ASICs technology is the front-end read out. We present here the instrumental and astrophysical performances of SuperAGILE as derived by Monte Carlo simulation and experimental tests.