Measurement of the angular correlation between the two gamma rays emitted in the radioactive decays of a Co-60 source with two NaI(Tl) scintillators

We implemented a didactic experiment to study the angular correlation between the two gamma rays emitted in typical Co-60 radioactive decays. We used two NaI(Tl) scintillators, already available in our laboratory, and a low-activity Co-60 source. The detectors were mounted on two rails, with the source at their center. The first rail was fixed, while the second could be rotated around the source. We performed several measurements by changing the angle between the two scintillators in the range from 90 degrees to 180 degrees. Dedicated background runs were also performed, removing the source from the experimental setup. We found that the signal rate increases with the angular separation between the two scintillators, with small discrepancies from the theoretical expectations.