Influence of light output calibration on neutron energy spectrum unfolding up to 300 MeV using liquid organic scintillator

The influence from uncertainty on light output calibration was studied experimentally for neutron energy spectra up to 300 MeV obtained by an unfolding method using a liquid organic scintillator. The neutrons were generated from the interactions of 100 and 290 MeV/u ²⁸ Si ion beams on thick silicon targets at a 75° direction with respect to the beam axis. The light output calibration determined by using Compton edges of γ-rays from ⁶⁰ Co and ²⁴¹ Am-Be sources was used for the unfolding method. The uncertainty of the calibration points at the Compton edges was estimated to be within 3%. Two calibration lines which connected the 3% larger light output point of the Compton edge of the γ-ray from ⁶⁰ Co and that the 3% lower light output point of that from ²⁴¹ Am-Be and vice versa were examined for influence on variation of calibration line. The unfolded spectra using the two calibration lines were compared with one using the calibration line connecting light output points of Compton edges from both γ-ray sources. The comparison indicates the uncertainty of calibration line influences the neutron light output spectrum within order of several %. The all unfolded spectra generally reproduced one by the time-of-flight (TOF) method in the same experiment. The difference between TOF and unfolded spectra were 17 and 8% for 100 and 290 MeV/u data, at maximum.