The processing by a radiation spectrometer of pulses resulting from the simultaneous adsorption of independent particles or photons in a radiation detector. As a result they are counted as one single particle or photon with energy between the individual energies and the sum of these energies.
Sources:
Orange Book, 2nd ed., p. 235 (https://media.iupac.org/publications/analytical_compendium/)
PAC, 1994, 66, 2513. 'Nomenclature for radioanalytical chemistry (IUPAC Recommendations 1994)' on page 2523 (https://doi.org/10.1351/pac199466122513)