Accuracy improving research on the calibration methods of organic scintillator detectors

The calibration accuracy of the response matrix has a critical effect on the accuracy and stability of the unfolded spectra of organic scintillator neutron spectrometers. In this paper, based on the calibration of an EJ-301 liquid scintillation detector, several optimization methods were proposed to improve the calibration accuracy. For gamma calibration, the influence of different coincidence components on the peak energies of the coincidence spectra was studied using Monte Carlo simulation, and the errors introduced by treating coincidence spectra as peaks of monoenergetic electrons in traditional methods were corrected by a well-designed iterative comparison method; the effect of electronic response nonlinearity on the Monte Carlo iterative calibration method was studied and then taken into account to further improve the calibration accuracy, reducing the relative deviation of the response to 4.438 MeV γ-rays from 3.31% to 0.61%. For neutron calibration, the calibration method based on isotope neutron sources and the time-of-flight technique was optimized under low-count conditions using an ionization quenching model. Finally, the calibration effect was validated using a DT neutron generator, and the results demonstrated that the methods proposed in this paper can significantly improve the calibration accuracy.