Processing by a radiation counter of pulses resulting from the simultaneous absorption of independent particles or photons in a radiation detector, resulting in them being counted as one single particle or photon with energy between the individual energies and the sum of these energies.
Source:
PAC, 2021, 93, 69. 'Vocabulary of radioanalytical methods (IUPAC Recommendations 2020)' on page 93 (https://doi.org/10.1515/pac-2019-0302)