Barium fluoride - inorganic scintillator for subnanosecond timing

The discovery of an intense, fast component of the light pulse from a BaF2 crystal coupled to a XP 2020 Q photomultiplier with quartz window prompted this detailed study of its properties as a scintillator. Light pulse shape investigations performed by means of the single photon method showed that the fast component is characterised by a decay time constant equal to 600 ps and by a fwhm equal to 550 ps. The intensity of it expressed by the number of photoelectrons released at the photocathode of the XP 2020 Q photomultiplier was equal to about 400 phe/MeV when the total light yield was measured to be equivalent to about 2000 phe/MeV. The time-resolved measurement of the emission spectrum showed that the fast component is due to the emission at 220 nm wavelength, the slow component is associated with 310 nm wavelength band. The energy resolution and time resolution studies performed with a number of crystals 24 mm in diameter and 1 to 4 cm thick showed that BaF2 combinex a lot of advantages: - a high time resolution equal to 112 ps for #betta#-rays from 60Co source; - a good energy resolution equal to 10% for 662 keV #betta#-rays from 137Cs source; - a very good efficiency for #betta#-ray detection due to a high density equal to 4.88 g/cm3. (orig.)