Development of large volume organic scintillators for use in the MASCO telescope

The development and construction of plastic scintillators of large volume, to be used as Compton suppressors in the MASCO telescope, are described. We also outline some characteristics of MASCO, which is a coded-mask gamma-ra y imaging telescope with an angular resolution of 14 in a 14 degrees (diame ter, conical) field-of-view with a sensitivity of 3.92, 1.33 and 1.18 x 10( -5) photons cm(-2) s(-1) keV(-1) in 0.05, 0.30 and 1 MeV respectively, for an integration time of 6 h and a residual atmosphere of 3.5 g cm(-2). The C ompton supressor described contains 12 modules of plastic scintillators, ea ch one built as a trapezoidal prism (1 m of length) with a cross section wi th sides of 14 x 22 cm(2) and 15 cm thick (271 of volume). Measurements of transmittance, luminescence, X-ray fluorescence and light output were carri ed out with the purpose of characterizing the detector. We present the esti mates of the imaging sensitivity and the sensitivity for pulsed sources of the MASCO instrument. (C) 1999 Elsevier Science B.V. All rights reserved.