Measurement of downhole radiation

An apparatus for evaluating an earth formation intersected by a borehole, the apparatus comprising:

• at least one detector configured to generate a plurality of signal pulses responsive to detected radiation;
• and
• at least one processor configured to:
• use the at least one detector to generate a plurality of signal pulses responsive to radiation detected while the detector is in the borehole;
• use 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 wherein the signal quality characteristic is indicative of a pulse pile-up condition being associated with the respective pulse;
• and
• use one of more of the plurality of pulse subsets to estimate a value of a parameter of interest.

A non-transitory computer-readable medium product for evaluating an earth formation comprising machine-readable instructions disposed on the medium that, when executed by a processor, cause the at least one processor to carry out a method, the method comprising:

• using a downhole tool in a borehole intersecting the formation 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, wherein the signal quality characteristic is indicative of a pulse pile-up condition being associated with the respective pulse;
• and
• using one of more of the plurality of pulse subsets to estimate a value of a parameter of interest.