基于GeTHU测量确定^(nat)Pb(p,x)^(207)Bi和^(nat)Pb(p,x)^(194)Hg的反应截面

Determination of cross-sections of ^(nat)Pb(p,x)^(207)Bi and ^(nat)Pb(p,x)^(194)Hg by GeTHU

加速器驱动次临界系统(Accelerator Driven Sub-critical System,ADS)是最具潜力的下一代核能系统选型之一,准确评估ADS散裂靶内产生的长寿命放射性核素含量是应用研究中的重要课题,利用质子活化法可以有效评价质子与散裂靶材料发生相互作用产生长寿命核素的反应截面。4个质子辐照天然铅样品分别被能量为40 MeV、70 MeV、100 MeV和400 MeV的质子照射90 min、75 min、40 min和25 min,在冷却约20 a后,利用中国锦屏地下实验室(China Jinping Underground Laboratory,CJPL)的超低本底γ谱仪GeTHU进行测量,使用SAGE(Simulation and Analysis for Germanium Experiments)模拟框架计算了GeTHU的探测效率,测定了能量为40 MeV、70 MeV、100 MeV和400 MeV质子与天然铅发生^(nat)Pb(p,x)^(207)Bi和^(nat)Pb(p,x)^(194)Hg反应的总产生截面,并与其他理论及实验工作的结果进行了比较,基于相同样品的实验测量结果在误差范围内保持一致,^(nat)Pb(p,x)^(207)Bi的反应截面与TENDL的评价截面更为接近,^(nat)Pb(p,x)^(194)Hg的截面结果与INCL++/ABLA的理论预期保持一致,这些截面结果为ADS设施的放射性废物评估提供了实验依据。

[Background]Accelerator-driven subcritical systems(ADS)are among the most promising options for next-generation nuclear power systems.Various radionuclides are produced during the process of protons bombarding the target in the ADS,and the cross-sections of various long-lived radionuclides have not been accurately measured.These long-lived nuclides are related to ADS radioactive waste treatment,therefore,accurate evaluation of long-lived radionuclides generated in ADS spallation targets is a key topic in applied research.[Purpose]This study aims to determinate production cross-sections of ^(nat)Pb(p,x)^(207)Bi and ^(nat)Pb(p,x)^(194)Hg reactions according to measurement data,and compare them with existing experimental and theoretical results.[Methods]The proton activation method was employed to effectively estimate the cross section of long-lived nuclides produced by the interaction between protons and spallation target materials.Four proton-irradiated natural lead samples were irradiated with protons at energies of 40 MeV,70 MeV,100 MeV,and 400 MeV for 90 min,75 min,40 min,and 25 min,respectively.After cooling for approximately 20 a,the samples were measured using an ultralow background gamma spectrometer GeTHU in the China Jinping Underground Laboratory(CJPL),and the GeTHU detection efficiency was calculated using the Simulation and Analysis for Germanium Experiments(SAGE)simulation framework.Combined with the irradiation parameters of the samples,the total production cross-sections of the two nuclides were calculated using a cross-section calculation formula.Experimental results are evaluated and compared with those of existing studies.[Results]The production cross-sections of ^(nat)Pb(p,x)^(207)Bi reaction in the natural lead samples irradiated by protons with four different energies(40 MeV,70 MeV,100 MeV and 400 MeV)are calculated as(40.70±3.59)mb,(19.31±1.43)mb,(13.15±0.96)mb,and(2.90±0.22)mb,respectively.The calculated production cross-section of ^(nat)Pb(p,x)^(194)Hg reaction in the natural lead sample irradiated by protons with an energy of 400 MeV is(57.07±7.83)mb.Based on the same samples,the measurement results of cross-section remain consistent within the error range.The cross-sections of ^(nat)Pb(p,x)^(207)Bi are closer to TENDL's evaluated cross-sections.The cross-section of ^(nat)Pb(p,x)^(194)Hg is consistent with the theoretical expectation of INCL++/ABLA.In addition,different sources that contribute to the total uncertainty of both reactions are explained in detail.[Conclusions]The production cross sections of ^(nat)Pb(p,x)^(207)Bi and ^(nat)Pb(p,x)^(194)Hg reactions measured herein were calculated independently and showed good agreement with existing results.These results demonstrate that GeTHU is capable of measuring low-activity and long-lived radionuclides in the CJPL.Finally,the results of this study also provide the latest experimental evidence for the evaluation of radioactive waste in ADS.