A Search for CPT-violation in Positronium

Speaker: Chelsea Bartram, U. North Carolina

When: May 22, 2018 (Tue), 03:30PM to 04:30PM (add to my calendar)
Location: PRB 261

This event is part of the HEE Seminar Series.

CALIOPE, or CP(T) Aberrant Leptons in o-Ps Experiment, is a search for CPT-violating angular correlations in the decay of ortho-positronium (o-Ps). Using a tagged source flush against a cylindrical piece of aerogel, we generate positronium at the center of APEX, an annular array of 24 NaI(Tl) bars. Gamma rays emitted in the decay of o-Ps interact in the NaI(Tl) and the resulting scintillation light is detected by PMTs that are optically coupled to the end of each bar. Signals from the PMT feed into the DAQ, which uses QDCs and TDCs to record the charge amplitude of pulses and timing information. I will present commissioning data from CALIOPE, including the first detection of o-Ps. I will discuss the design of the DAQ and process of isolating o-Ps events using various analysis cuts. I also will present a detailed study of systematics resulting from Geant4 Monte Carlo simulations and our anticipated improvement over a previous search for CPT-violation in o-Ps.