ENERGY RESOLUTION TESTS OF 125 MM DIAMETER CYLINDRICAL NE213 DETECTOR USING MONOENERGETIC GAMMA-RAYS

Pulse height tests have been carried out for cylindrical NE213 liquid scintillation detectors of diameters 50 and 125 mm, using monoenergetic gamma rays. The 125 and 50 mm NE213 scintillator cells, each having a thickness of 50 mm, were directly coupled to 130 mm and 52 mm diameter photomultipliers respectively. Gamma-gamma coincidence technique was used to determine the detector's energy resolution and pulse height corresponding to the maximum energy of Compton electrons over the gamma rays energy range of 0.5-1.2 MeV. For the 125 mm detector, the energy corresponding to half height of Compton maxima is 14.4-6.6% higher than the maximum energy of Compton electrons while its energy resolution varies from 24.0 to 18.0%. For the 50 mm detector the energy corresponding to half height of Compton maxima is 9.8-4.0% higher than the maximum energy of Compton electrons while its energy resolution varies from 18.8 to 12.2%. For the 125 mm diameter detector results are presented for the first time.