Systems, methods and devices for evaluating an earth formation intersected by a borehole. Method embodiments may include using a downhole tool in the borehole to generate a plurality of signal pulses responsive to detected radiation; using at least one signal quality characteristic of each pulse of the plurality of pulses to classify each pulse as belonging to at least one subset of a plurality of pulse subsets; and using one of more of the plurality of pulse subsets to estimate a value of a parameter of interest. The signal quality characteristic may be indicative of a pulse pile-up condition being associated with the respective pulse. The signal quality characteristic may include at least one of: i) rising time (slope) of the respective pulse; ii) time between a peak of the respective pulse and a peak of a closest following pulse; iii) pulse width; and iv) skewness of the pulse.