DNP Seminar

09-02-2026 11:00 Conference hall (bldg. 42, 3rd floor)

"Quantitative analysis of hidden neutron cross section in a multi-detector spherical chamber based on the EJ-309 scintillator"

Olga Sidorova, Shakir Zeynalov

Numerical simulation of neutron cross section in a multi-detector spherical chamber with cylindrical detectors based on the EJ-309 organic scintillator in the energy range of 100-4800 keV has been carried out. Based on 2D H-maps that take into account only the energy transmitted to the protons, a technique has been proposed for dividing background events into four zones. The component of the hidden cross section has been highlighted - events for which the signal in the target detector is below the amplitude threshold of discrimination and in the neighboring one - above. It has been shown that raising the threshold does not suppress the hidden cross section but results in reclassification of visible events into hidden ones, worsening the diagnosability of the background. It has been found that in inter-resonance areas the hidden cross section is 4-16% of the total H-cross current and at elastic n-C scattering resonances (2079, 2819, 3580 and 4200 keV) it increases to 28-30%. A threshold selectivity factor has been introduced, justifying the optimality of the lowest possible threshold (~ 50 keV on the proton scale). For practical evaluation of the hidden background, according to experimental data, the hidden background coefficient HBR is proposed that is 0.2-0.6% outside the resonances and reaches 1.7-1.9% at carbon resonances. This technique allows quantifying the number of background events in the "blind zone" without implementing a complete simulation of the scintillator.