1-a) Exponential decay is observed due to the characteristic lifetime of excited states, commonly seen in processes like radioactive decay.
1-b) The fewer events/counts in detector combination 1-2 compared to 1-3 stem from the orientations relative to the nuclei. Detector 1, parallel to the nuclei, has high detection probability. Detector 2, perpendicular to both nuclei and detector 1, has lower probability. Detector 3, aligned with the nuclei, has higher detection likelihood.