Measurement of fusion neutron yields in laser–cluster fusion experiments using binomial statistics

Accurate neutron-yield measurement is essential for fusion plasma diagnostics. In laser-driven fusion experiments, short-pulse quasi-monoenergetic neutrons can overlap within a narrow time-of-flight (TOF) window, leading to an underestimation of the yield in conventional pulse-counting analysis. Here, we demonstrate a neutron-yield measurement based on binomial statistics over a series of TOF acquisitions. Without resolving single- and multiple-neutron detection events, the yield was determined from the binomial proportion of zero-detection acquisitions, thereby avoiding pulse pile-up-induced undercounting. 2.45 MeV DD fusion neutrons were generated by irradiating deuterium clusters with 100 TW laser pulses, and neutron TOF spectra were measured. Neutron yields on the order of 10 2 –10 5 neutrons per shot were measured over an ion temperature range of 2–20 keV. A fusion neutron-yield model reproduced the observed increase in neutron yield with ion temperature. The measured neutron yields agreed well with those from a separate deconvolution analysis using the average single-neutron response, indicating that the binomial analysis enables robust yield measurement over a broad range of detection rates without pile-up-induced underestimation. Analytical estimates showed that the statistical uncertainty in the measured yield is minimized at a zero-detection probability near 0.2, providing a practical guideline for efficient pulse-counting neutron-yield measurements with finite acquisitions.