Real-time algorithm for robust coincidence search
In in-beam {gamma}-ray spectroscopy experiments, we often look for coincident detection events. Among every N events detected, coincidence search is naively of principal complexity O(N{sup 2}). When we limit the approximate width of the coincidence search window, the complexity can be reduced to O(N), permitting the implementation of the algorithm into real-time measurements, carried out indefinitely. We have built an algorithm to find simultaneous events between two detection channels. The algorithm was tested in an experiment where coincidences between X and {gamma} rays detected in two HPGe detectors were observed in the decay of {sup 61}Cu. Functioning of the algorithm was validated by comparing calculated experimental branching ratio for EC decay and theoretical calculation for 3 selected {gamma}-ray energies for {sup 61}Cu decay. Our research opened a question on the validity of the adopted value of total angular momentum of the 656 keV state (J{sup {pi}} = 1/2{sup -}) in {sup 61}Ni.