Spectrometer for studying angular correlations in polarized orthopositronium decay

The facility, intended for conducting an experiment on testing the CPT invariance through observation of angular correlations by the positronium polarized atoms decay, is described. The annihilation acts are fixed by five scintillation detectors on the NaI(Tl) basis, located at the tops of a regular pentagon. The signals from the detectors are registered in binary majority coincidences, strobed by signals. delayed for different time relative to the positronium departure; the facility resolution time is 8.0 ns. Turning the direction of the positronium entry into the SiO2 target by 180 deg is accomplished for decreasing the effect of the apparatus long-time instability and apparatus asymmetry on the experimental results in the process of the data collection. The asymmetry measured value equaled 0.0008 ± 0.00091, which by two times is more accurate as compared to the previous experiment