Construction of a position-sensitive scintillation detectors system to view the laser cooled ortho-positronium

We are attempting to construct a position-sensitive scintillation detectors system to view the laser-cooled ortho-positronium. In spite of the short lifetime of ortho-positronium (142 ns) produced at room temperature can be cooled down to the recoil limit of 0.1 K by ultra violate laser. The wavelength of Cr:LiSAF laser is selected to be 243 nm which corresponds to the 1S-2P transition energy of ortho-positronium. Thermal positronium plays an important role to realize the laser cooling of ortho-positronium. Different kinds of inorganic scintillator have been investigated to optimize one in our experiment. Position resolutions of YAP:Ce, and CsI(Tl) based position-sensitive multianode photomultiplier tubes detectors respectively are determined to be 4.0 mm, and 4.7 mm. YAP:Ce scintillator is recently developed and might be a good candidate for our experimental purpose due to high light output, short decay time and excellent stopping power. An extensive Monte Carlo simulation studies have been performed to understand the utility of this system. Related issues of position resolution measurements and a view of spatial distribution of ortho-positronium annihilation points will be illustrated.