Measurement of the angular correlation between the two gamma rays emitted in the radioactive decays of a $^{60}$Co source with two NaI(Tl) scintillator

TL;DR

This experiment measured the angular correlation of gamma rays emitted by a $^{60}$Co source using two NaI(Tl) scintillators, demonstrating an increase in signal rate with angle, with some deviations from theory.

Contribution

The study presents a didactic setup for measuring gamma-ray angular correlation using common laboratory equipment, providing practical insights into nuclear decay processes.

Findings

Signal rate increases with angular separation.

Small discrepancies observed compared to theoretical predictions.

Experimental setup effectively demonstrates angular correlation principles.

Abstract

We implemented a didactic experiment to study the angular correlation between the two gamma rays emitted in typical $^{60}$Co radioactive decays. We used two NaI(Tl) scintillators, already available in our laboratory, and a low-activity $^{60}$Co 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 $90^\circ$ to $180^\circ$. 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.