Feasibility of a Nal(Tl) Scintillation Bar Detector for Measurement of Radioactive Contamination

Feasibility of a Nal(Tl) scintillation bar detector for the measurement of radioactive contamination has been studied. The scintillator has dimensions of 6.35×6.35×71.12cm3. Its surface is polished to obtain the information of position. Two photomultiplier tubes (PMTs) are mounted on both sides of the bar scintillator. The position where an incident gamma-ray interacts with the scintillator is determined from the difference of light output between the two PMTs. The energy distribution deposited in the scintillator is obtained by summing up the output signals. For a collimated 60Co source, the position and energy resolutions at the center of bar detector were 3.1cm ( FWHM ) and 6.3% at the energy of 1.33MeV, respectively. For a collimated 137Cs source, the resolutions were 3.4cm and 9.8%, respectively. For the 60Co point source, the lead plates of lcm thick and 10cm length were used as a collimator with the intervals of 5cm in order to prevent the spatial extent of radiation. Then, the source position plac...