<p>The prompt fission neutron spectrum (PFNS) is a key nuclear data quantity that is of particular interest and plays a crucial role in understanding and modeling fission processes. An array comprising 48 liquid scintillation detectors and a parallel-plate avalanche counter (PPAC) was developed at the China Institute of Atomic Energy (CIAE) to measure the PFNS of actinide nuclei. Efficiency and energy calibrations were performed for all the liquid scintillators, and their efficiencies were consistently found to be better than 5%. The time resolutions of the PPAC and liquid scintillators were measured to be 1.08 ns and 1.16 ns using <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1649_Article_IEq1.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="36" /> </InlineMediaObject> <EquationSource Format="TEX">$^{252}\hbox {Cf}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mmultiscripts> <mrow /> <mrow /> <mn>252</mn> </mmultiscripts> <mtext>Cf</mtext> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1649_Article_IEq2.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="36" /> </InlineMediaObject> <EquationSource Format="TEX">$^{207}\hbox {Bi}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mmultiscripts> <mrow /> <mrow /> <mn>207</mn> </mmultiscripts> <mtext>Bi</mtext> </mrow> </math></EquationSource> </InlineEquation> sources, respectively. The pulse shape discrimination of the liquid scintillator was utilized to identify neutron and <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1649_Article_IEq3.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="13" /> </InlineMediaObject> <EquationSource Format="TEX">$\gamma$</EquationSource> <EquationSource Format="MATHML"><math> <mi>γ</mi> </math></EquationSource> </InlineEquation> signals on an event-by-event basis, and the figure of merit was deduced as 1.12 at a 200 keVee threshold. The contribution to the PFNS from multiple scattered neutrons was evaluated via Geant4 simulations, and those originating from the environment were found to be comparable to the crosstalk between the detectors. The neutron efficiency of the entire detection array was calibrated using a <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="41365_2025_1649_Article_IEq4.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="36" /> </InlineMediaObject> <EquationSource Format="TEX">$^{252}\hbox {Cf}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mmultiscripts> <mrow /> <mrow /> <mn>252</mn> </mmultiscripts> <mtext>Cf</mtext> </mrow> </math></EquationSource> </InlineEquation> spontaneous fission source and was demonstrated to be consistent with the Geant4 simulation results, which verified the reliability of the detection array.</p>

Commissioning of the fast neutron detector array at China Institute of Atomic Energy

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发表日期：

2025年3月20日

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Meng-Xiao Kang,
Ji-Zhi Zhang,
Hong-Yi Wu,
Han-Xiong Huang,
Yu-Zhao Li,
He-Run Yang,
Xi-Chao Ruan

摘要

The prompt fission neutron spectrum (PFNS) is a key nuclear data quantity that is of particular interest and plays a crucial role in understanding and modeling fission processes. An array comprising 48 liquid scintillation detectors and a parallel-plate avalanche counter (PPAC) was developed at the China Institute of Atomic Energy (CIAE) to measure the PFNS of actinide nuclei. Efficiency and energy calibrations were performed for all the liquid scintillators, and their efficiencies were consistently found to be better than 5%. The time resolutions of the PPAC and liquid scintillators were measured to be 1.08 ns and 1.16 ns using $^{252}\hbox {Cf}$ $^{252} Cf$ and $^{207}\hbox {Bi}$ $^{207} Bi$ sources, respectively. The pulse shape discrimination of the liquid scintillator was utilized to identify neutron and $\gamma$ $γ$ signals on an event-by-event basis, and the figure of merit was deduced as 1.12 at a 200 keVee threshold. The contribution to the PFNS from multiple scattered neutrons was evaluated via Geant4 simulations, and those originating from the environment were found to be comparable to the crosstalk between the detectors. The neutron efficiency of the entire detection array was calibrated using a $^{252}\hbox {Cf}$ $^{252} Cf$ spontaneous fission source and was demonstrated to be consistent with the Geant4 simulation results, which verified the reliability of the detection array.