1. A mass spectrometer, comprising: an ion pulser operable to accelerate ions in response to temporally-irregular transients, the transients having an average repetition rate greater than a reference repetition rate that depends on a maximum time of flight of the mass spectrometer, each of the transients having a respective transient time; an ion detector operable to generate a detection signal in response to the ions incident thereon, the detection signal representing detection events each comprising a respective intensity and a respective event time; an allowed time of flight calculator operable in response to the transient times and the event time of the detection event to determine, for each detection event represented by the detection signal, respective allowed times of flight (TOFs) linked to the detection event; a spectrum memory comprising time-of-flight (TOF) bins each corresponding to a respective one of the allowed TOFs; and an intensity apportioner and accumulator operable to use initial probabilities to determine an apportionment of the respective intensity of each detection event among the allowed TOFs linked thereto and to accumulate the apportionments of the intensities to each allowed TOF to generate a respective intensity accumulation for output to the respective TOF bin corresponding to the allowed TOF, the intensity apportioner additionally iteratively operable, for each detection event, to determine revised probabilities using the intensity accumulations stored in the TOF bins corresponding to the allowed TOFs linked to the detection event, and to reapportion the respective intensity among the allowed TOFs linked to the detection event using the revised probabilities.