Showing papers by "G. Di Cocco published in 1996"

The EPIC system onboard the ESA XMM mission

Abstract: The European Photon Imaging Camera (EPIC) is one of the two main instruments onboard the ESA X-Ray Cornerstone mission XMM. It is devoted to performing imaging and spectroscopy of the X-Ray sky in the domain 0. 1-10 keV with a peak sensitivity in i0 seconds of 2x10'5 erg/cm2. The X-ray instrumentation is complemented by a radiation monitor which will measure the particle background. The spectral resolution is approximately 140 eV 6.4 keV and 60 eV @ 1 keV. The instrumentation consists of three separate Focal Plane Cameras at the focus of the three XMM telescopes, containing CCDs passively cooled to typically -100° via radiators pointing toward the anti-Sun direction. The two cameras with the field ofview partially occulted by the RGS Grating Boxes will have MOS technology CCDs while the third camera, with full field of view, will be based on p-n technology. The CCDs in the focal plane of the Cameras will cover the entire 30'x30' field of view of the telescope while the pixel size (40x40.t for the MOS camera and 150x150 for the p-n ) will be adequate to sample the '—20" PSF of the mirrors. In order to cope with a wide range of sky background and source luminosity in the visiblelEJV band, a filter wheel with six positions has been implemented in each Camera. The six positions correspond to: open position, closed position, one thin filter (1600 A of plastic support and 400 A of Al) , one medium filter (1600 A of plastic support and 800 A of Al) and one thick filter (--3000 A of plastic support, 4000 A of Al and 300 A of Sn). The final position will be a redundant filter of type still to be decided. A set of radioactive sources in each camera will allow the calibration of the CCDs in any of the operating modes and with any filter wheel position. Vacuum doors and valves operated will allow the operation of the Camera Heads on the ground, in a vacuum chamber and/or in a controlled atmosphere, and will protect the CCDs from contamination until the spacecraft is safely in orbit. The MOS camera will have 7 CCDs, each of 600 x 600 pixels arranged in a hexagonal pattern with one central and six peripheral. The p-n camera head will have 12 CCDs, each with 200x64 pixels, in a rectangular arrangement, 4 quadrants of 3 CCDs each. The Radiation Monitor is based on two separate detectors to monitor the Low ( electrons >30 keV ) and the High (electrons >200 keV and protons >10 MeV) energy particles impinging on the telescope along its orbit.

Background rejection for the IBIS telescope based on Compton kinematics: experimental tests and Monte Carlo simulations

Abstract: IBIS (Imager on Board the Integral Satellite) is dedicated to fine imaging in the gamma-ray energy range. The imaging performances are achieved using a coded mask aperture system in conjunction with a position sensitive detector made of two layers. This multilayer structure of position sensitive detectors allows the application of Compton kinematics for background rejection. In order to determine the efficacy of this method, a reduced scale prototype of the instrument has been developed. The detection apparatus is composed by two scintillation matrices of 5/spl times/5 elements in the same configuration of IBIS. The upper layer pixel size is 13/spl times/13/spl times/3 mm whereas the lower layer pixel size is 13/spl times/13/spl times/30 mm. An hybrid technology electronics has been setup for signals shaping and discrimination, moreover a custom software package has been developed for system calibration and data analysis. The equipment has been tested at different energies by employing radioactive sources. The results are presented and compared, when possible, with Monte Carlo simulations.