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-ray imaging telescope with an angular resolution of 14 in a 14° (diameter, conical) field-of-view with a sensitivity of 3.92, 1.33 and 1.18×10−5 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 Compton supressor described contains 12 modules of plastic scintillators, each one built as a trapezoidal prism (1 m of length) with a cross section with sides of 14×22 cm2 and 15 cm thick (27 l of volume). Measurements of transmittance, luminescence, X-ray fluorescence and light output were carried out with the purpose of characterizing the detector. We present the estimates of the imaging sensitivity and the sensitivity for pulsed sources of the MASCO instrument.