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The project of a new calorimeter module for Compton telescopes based on an array of silicon drift detectors (SDD) coupled to thallium activated cesium iodide (CsI(Tl)) scintillating crystals is presented. Because of their low output capacitance and the possibility to have the first amplifying stage directly integrated on chip, SDDs show better noise performances than traditional p-intrinsic-n (PIN) photodiodes. For this reason, SDDs coupled to scintillators show a higher energy resolution than similar systems based on PIN photodiodes. The detectors will be integrated in an array with read-out based on custom made ASIC’s built to match with the SDDs electrical properties. Shaped signals are digitally converted by a Digital Front-End Electronic Board which also takes care of ASICs handshaking. The system architecture is based on the PICsIT instrument on board the INTEGRAL satellite, at present fully operative. In this paper an overview of the instrument will be given and the status of the project will be reported.

AGILE is an ASI (Italian Space Agency) small space mission for high energy astrophysics in the gamma ray energy range 30MeV–50GeV, and in the X-ray band 10keV–40keV. AGILE is composed of three scientific detectors: a TungstenSilicon Tracker, a CsI Mini-Calorimeter and a Silicon based X-ray detector (Super-Agile), moreover an anticoincidence system carries out background rejection. The satellite’s payload will have good imaging performances (with angular resolution of a few arc-minutes in the gamma ray band), good timing resolution and a large field of view (about 1/5 of the sky). AGILE detection principle is based on the pair production process that arises from the interaction between high energy photons and the Tungsten layers of the Silicon Tracker. The Silicon Tracker is designed to determine the direction of the incoming radiation, while the Mini-Calorimeter evaluates the energy of the interacting photons. The Mini-Calorimeter can also work as a stand-alone gamma ray detector in the energy range 250keV–250MeV, with no imaging capabilities, for the detection of transients and gamma ray burst events (in cooperation with Super-Agile) and for the evaluation of gamma ray background fluctuations. In this paper a description of the Mini-Calorimeter is done.

PICsIT (Pixellated Imaging CaeSium Iodide Telescope) is the high energy detector of the IBIS telescope on-board the INTEGRAL satellite. PICsIT operates in the gamma-ray energy range between 175 keV and 10 MeV, with a typical energy resolution of 10% at 1 MeV, and an angular resolution of 12 arcmin within a \~100 square degree field of view, with the possibility to locate intense point sources in the MeV region at the few arcmin level. PICsIT is based upon a modular array of 4096 independent CsI(Tl) pixels, ~0.70 cm^2 in cross-section and 3 cm thick. In this work, the PICsIT on-board data handling and science operative modes are described. This work presents the in-flight performances in terms of background count spectra, sensitivity limit, and imaging capabilities., 8 pages, 4 figures. Accepted for publication on A&A, special issue on First Science with INTEGRAL

The study of γ rays is fundamental for our understanding of the universe: γ rays probe the most energetic phenomena occurring in nature, and several signatures of new physics are associated with the emission of γ rays. The main science objectives and the status of the new generation high-energy gamma-ray astrophysics experiment AGILE are presented.

AGILE is an ASI Small Scientific Mission dedicated to gamma-ray astrophysics, which will detect and image photons in the 30 MeV – 50 GeV and in the 10–40 keV energy ranges. It is planned to be operational in early 2004 and it will be the only Mission entirely dedicated to source detection above 30 MeV during the period 2004–2006. AGILE will be an excellent gamma-ray imager with a spatial resolution of ∼ 40 μm and a very large FOV (∼ 1/5 of the sky). It allows simultaneous observations in the hard X-ray and in the γ-ray bands and it is characterized by an optimal temporal resolution (absolute timing of ∼ 2 μs and deadtimes of ∼ 100 μs for the GRID and of ∼ 5 μs for Super-AGILE and the Mini-Calorimeter). AGILE main scientific objectives will be: Active Galactic Nuclei, Gamma-Ray Bursts, Pulsars, unidentified gamma-ray sources and diffuse Galactic and extragalactic gamma-ray emission. In this paper (Part I) we focus on the AGILE scientific goals, the AGILE instrument and the on-board data processing.

AGILE is an ASI (Italian Space Agency) Small Space Mission for high energy astrophysics in the range 30 MeV - 50 GeV which is planned to be launched in 2005. Mechanical equipments are required for the Assembly, Integration and Verification (AIV) of the various subsystems together, forming the Payload complement. Furthermore, the calibration of the AGILE's performances requires to test with a beam line and with discrete X and γ ray sources the instrument response as a function of the energy of the incoming photons and particles and of their inclination with respect to the instrument axis. These AIV and Calibration activities lead to require an ad hoc Mechanical Ground Support Equipment (MGSE) which is able to move the instrument up and down, left and right as well as to rotate the instrument around the vertical axes and to tilt it by an angle between 0 and 180° with reference to the direction of the beam. We present here the MGSE we have designed in order to provide these functionalities with the required performances, and taking into account the working environment of the AIV and calibration sites.

AGILE is an ASI (Italian Space Agency) Small Space Mission for high energy astrophysics in the range 30 MeV - 50 GeV which is planned to be launched in 2005. The AGILE payload complement consists of a Tungsten-Silicon Tracker, a CsI Minicalorimeter, an anticoincidence system and a X-Ray detector sensitive in the 10-40 KeV range. The Minicalorimeter detector shall contribute to the determination of the energy interacting gamma-rays and will allow the detection of Gamma Ray Burst and other impulsive events from around 300 KeV. The MCAL Science Console software is part of the test equipment which provides support to the integration, verification and calibration of the Minicalorimeter from the Simplified Electrical Model (SEM) to the Protoflight model (PFM). We describe here the software version we have developed for the SEM test equipment, and which has been used during the functional, performance and calibration test campaign carried out in 2003 on the SEM Minicalorimeter model. In particular we address the performance and architectural issues in view of the next release to be procured for the Minicalorimeter PFM

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 prototype Application Specific Integrated Circuit (ASIC) to read out signals from Silicon Drift Detector has been realised and characterised. The device is based on the ICARUS ASIC that is currently employed into the PICsIT detector on board the INTEGRAL satellite http://astro.estec.esa.nl/Integral/integral.html. The first stage of the charge preamplifiers collecting the signals from the detectors is mounted externally to the ASIC. The ASIC functional behaviour is described and its performances are summarised and discussed.

The Italian Small Scientific Satellite AGILE is designed to operate in the energy range 30 MeV-50 GeV and will achieve an angular resolution of 5 to 20 for intense sources over a large field of view (better then 2 sr). The payload consists of a X-ray imaging detector (Super-Agile), a Silicon-Tungsten Tracker, a Cesium Iodide Mini-Calorimeter, an anticoincidence system, fast readout electronics and processing unit. The Mini-Calorimeter, comprises 2 orthogonal planes each consisting of 16 bars of CsI(Tl), it will contribute to the determination of the energy of the interacting gamma-rays and will allow the detection of Gamma Ray Bursts and other impulsive events from around 300 keV. A prototype of the Mini-Calorimeter has been tested both with laboratory sources and with charged particles (1 - 2 GeV/c) during some dedicated test campaign carried out in August 1999, in May 2000 and in November 2000 at the CERN T11 beamline (East Hall, CERN PS). The test set-up was completed with a prototype of the flight frontend electronic chain. A prototype of the digital data acquisition chain, which will be the basis of the payload Electronic Ground Support Equipment, has also been built and tested. The tests have been devoted to detector unit characterization and electronic characterization. The results of the tests carried out in 2000 are described and discussed.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The AGILE Mini-Calorimeter (MCAL, with total on-axis radiation length 1.5 X0) comprises 2 orthogonal planes each consisting of 16 CsI(Tl) bars. Its primary purpose is the energy determination of gamma-rays detected by the Gamma-Ray Imaging Detector (GRID) Tracker (energy range 30 MeV–50 GeV). In addition, the MCAL is capable of independently triggering and detecting gamma-ray bursts and other impulsive events in the energy range 0.25–250 MeV. A MCAL prototype, comprising 8 CsI(Tl) detector elements, was tested both with laboratory sources and with charged particles (p=1 GeV/c) during an AGILE Beam Test carried out in November 2000 at the CERN T11 beamline (East Hall, CERN PS). The test setup included a prototype of the electronic chain. A prototype of the digital data acquisition chain, which will be the baseline of the payload Electronic Ground Support Equipment, was also built and tested. We present the preliminary results of this test campaign dedicated to characterizing the detector unit and electronics.

The AGILE satellite is designed to observe emission in the energy range from 30 MeV to 50 GeV from a variety of celestial objects such as Galactic sources, Active Galactic Nuclei, gamma ray bursts, solar flares and unidentified objects as well as diffuse emission. It is intended to be operational for a period of 3 years from the foreseen launch date of 2002. In the intervening time the instrument will proceed from the design phase, through the construction, test and calibration to the flight ready status. In order to support these activities a dedicated Ground Support Equipment (GSE), including both mechanical and electrical items will be required. Herein we describe the architecture of the GSE with particular reference to the items devoted to the scientific data acquisition, archiving and processing and to the control of the detector position in the calibration beam facility.

The AGILE (Astro-rivelatore Gamma a Immagini LEggero) satellite is an accepted mission by the ASI (Italian Space Agency) for Small Scientific Payload as a powerful and cost- effective space mission dedicated to gamma-ray (30 MeV to 50 GeV) astrophysics during the years 2002 - 2005. The instrument is designed to achieve an optimal angular resolution (about 5' - 20' for intense sources) and a large field-of-view (better than 2 sr.). The AGILE scientific payload consists of a silicon-tungsten tracker, a Cesium Iodide mini-calorimeter, an anti-coincidence system made of plastic scintillators, fast read-out electronics and processing units. The mini- calorimeter detector is made of 2 orthogonal planes each one comprising 16 bars of CsI(Tl) each having a cross section of 1.5 X 2.3 cm and a length of 40 cm. The signal from each bar is collected by photo-diodes placed at both ends with the aim of: (1) obtaining information on the energy deposited in the bars by particles produced in the tracker and therefore contributing to the determination of the total energy. (2) detecting Gamma Ray Bursts and other impulsive events in the energy range 0.25 - 100 MeV. Two bars have been tested in the ITeSRE laboratory using 241Am and 22Na radioactive sources and at the CERN (European Center for Nuclear Radiation, Geneva) facilities using a beam of charged particles at the energy of 2 GeV/c. In this paper, after a short description of the experimental set-up, the performance of the two bars in terms of equivalent charge output, light attenuation, position and energy reconstruction as a function of the distance from the bars' center are reported. Moreover the results of a first approach to a Monte Carlo simulation of the bars are compared with experimental data.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

AGILE is an ASI (Italian Space Agency) Small Space Mission for high energy astrophysics in the range 30 MeV – 50 GeV. The AGILE satellite is currently in the C phase and is planned to be launched in 2005. The Payload shall consist of a Tungsten‐Silicon Tracker, a CsI Minicalorimeter, an anticoincidence system and a X‐Ray detector sensitive in the 10–40 KeV range. The purpose of the Minicalorimeter (MCAL) is twofold. It shall work in conjunction with the Tracker in order to evaluate the energy of the interacting photons, and it shall operate autonomously in the energy range 250KeV–250 MeV for detection of transients and gamma ray burst events and for the measurement of gamma ray background fluctuations. We present the architecture of the Test Equipment we have designed and developed in order to test and verify the MCAL Simplified Electrical Model prototype which has been manufactured in order to validate the design of the MCAL Proto Flight Model.

In angiographic practice an iodate contrast medium is injected in patient vessels with a catheter. The iodine is used because its linear absorption coefficient shows a K-edge at 33.169 keV. In Digital Subtraction Angiography (DSA), some images are acquired before and during the injection of the contrast medium. The vessels' morphology is obtained by subtracting the live images from the first (mask) image. A new approach is presented where two quasi-monochromatic beams, having mean energies lower and higher than the iodine K-edge, are produced simultaneously - starting from an X-ray tube - by means of a pyrolytic graphite crystal monochromator. These two thin parallel beams impinge on the phantom simulating patient vessels and are detected with solidstate array detectors. The image results as the difference between the remaining intensities of the two beams. Performance - in terms of spatial resolution, contrast and reduction of iodine concentration in an invasive perfusion medium - will be presented and compared with the full spectra subtraction method in use.

AGILE will explore the gamma‐ray Universe with a very innovative instrument combining for the first time a gamma‐ray imager and a hard X‐ray imager. AGILE will be operational in spring 2007 and it will provide crucial data for the study of Active Galactic Nuclei, Gamma‐Ray Bursts, unidentified gamma‐ray sources. Galactic compact objects, supernova remnants, TeV sources, and fundamental physics by microsecond timing. The AGILE instrument is designed to simultaneously detect and image photons in the 30 MeV – 50 GeV and 15 – 45 keV energy bands with excellent imaging and timing capabilities, and a large field of view covering ∼ 1/5 of the entire sky at energies above 30 MeV. A CsI calorimeter is capable of GRB triggering in the energy band 0.3–50 MeV AGILE is now (March 2007) undergoing launcher integration and testing. The PLSV launch is planned in spring 2007. AGILE is then foreseen to be fully operational during the summer of 2007.