Measurements of the ^(107)Ag neutron capture cross sections with pulse height weighting technique at the CSNS Back-n facility

Silver indium cadmium(Ag–In–Cd) control rod is widely used in pressurized water reactor nuclear power plants,and it is continuously consumed in a high neutron flux environment. The mass ratio of ^(107)Ag in the Ag–In–Cd control rod is 41.44%. To accurately calculate the consumption value of the control rod, a reliable neutron reaction cross section of the ^(107)Ag is required. Meanwhile,^(107)Ag is also an important weak r nucleus. Thus, the cross sections for neutron induced interactions with ^(107)Ag are very important both in nuclear energy and nuclear astrophysics. The(n, γ) cross section of ^(107)Ag has been measured in the energy range of 1–60 eV using a back streaming white neutron beam line at China spallation neutron source. The resonance parameters are extracted by an R-matrix code. All the cross section of ^(107)Ag and resonance parameters are given in this paper as datasets. The datasets are openly available at http://www.doi.org/10.11922/sciencedb.j00113.00010.

Measurement of fast-neutron capture cross sections for ^(75)As

The cross sections of the75 As(n,γ)76As reaction were measured in the neutron energy range from 0.50 to 1.50 MeV by using the activation technique. Neutrons were produced via the T(p,n)3He reaction and the cross sections of the 197Au(n,γ)198Au reaction were used to determine the absolute neutron flux. Present results are compared with existing measurements and evaluations.

Measurements of fast-neutron capture cross sections for ^(159)Tb and ^(169)Tm

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Measurement of Neutron Capture Cross Section for ^(180)Hf

The neutron capture cross section for 180Hf relative to the 197Au（n,γ）198Au reaction ismeasured at neutron energies of 0.52,1.10 and 1.60 MeV using the activation method.Theactivities of the products are measured with a high resolution HPGe detector gamma ray spec-trometer.The errors of the measured results are 5%～6%.Our results have a good agreementwith those of other authors within errors.Cross sections for the reaction are calculated withUNF code and recommended data are also given.

Measurement of Neutron Radiative Capture Cross Section for ^(56)Fe(n,γ)^(57)Fe Reaction From 9.0 to 20.0 MeV

Neutron radiative capture cross sections of 56Fe（n,γ）57Fe reaction have beenmeasured in two incident energy ranges,from 9.3 to 16.0 MeV at 90° and from 9.0 to20.0 MeV at 55° and 125°.Time-of-flight technique is used to discriminate neutronsand gamma rays.The asymmetry of fore and aft γ-ray in this reaction is obtained.

Measurement of Neutron Capture Cross Section for ^(152)Sm

The cross sections for 152Sm（n,γ）153Sm relative to 197Au neutron capture crosssection are measured by activation method in neutron energy range of 22-1019 keV.The results are compared with the previous work.

Measurement of Br(n,γ)cross sections up to stellar s-process temperatures at the CSNS Back‑n

The neutron capture cross sections(n,γ)of bromine were obtained using the time-of-flight technique at the Back-n facility of the China Spallation Neutron Source.Promptγ-rays originating from neutron-induced capture events were detected using four C_(6)D_(6) detectors.The pulse-height weighting technique and double-bunch unfolding method based on Bayesian theory were used in the data analysis.Background deductions,normalization,and corrections were carefully considered to obtain reliable measurement results.The multilevel R-matrix Bayesian code SAMMY was used to extract the resonance parameters in the resolved resonance region(RRR).The average cross sections in the unresolved resonance region(URR)were obtained from 10 to 400 keV.The experimental results were compared with data from several evaluated libraries and previous experi-ments in the RRR and URR.The TALYS code was used to describe the average cross sections in the URR.The astrophysical Maxwell average cross sections(MACSs)of ^(79,81)Br from kT=5 to 100 keV were calculated over a sufficiently wide range of neutron energies.At a thermal energy of kT=30 keV,the MACS value for ^(79)Br 682±68 mb was in good agreement with the KADoNiS v1.0 recommended value.By contrast,the value of 293±29 mb for ^(81)Br was substantially higher than that of the evaluated database and the KADoNiS v1.0 recommended value.

Measurement of neutron capture cross section on^(71)Ga at 2.15 and 3.19 MeV and uncertainty propagation and covariance analysis

The cross section values of the^(71)Ga(n,γ)^(72)Ga reaction are measured,which are 9.14±0.81 mb and 5.74±0.50 mb at 2.15 and 3.19 MeV,respectively.The detailed uncertainty propagation and covariance analysis are also given.The^(7)Li(p,n)^(7)Be reaction was used to generate the neutrons,and the neutron flux was normalized using the^(115)In(n,n′)^(115)In^(m)monitor reaction.The measured cross section data are compared with the data available in the EXFOR database,the data obtained using nuclear reaction model codes EMPIRE-3.2 and TALYS-1.95,and also the evaluated nuclear data from ENDF/B-VIII.0 and JEFF-3.1/A.The comparison shows that our result at 3.19 MeV is in good agreement with those of EMPIRE-3.2 and JEFF-3.1/A.Since there are no other measurements available at3.19 MeV,our data could not be compared with literature data at 3.19 MeV,but they are consistent with the cross section values available at 2.98±0.26 and 3.0±0.1 MeV.Our result at 2.15 MeV is slightly higher than the literature value available in EXFOR,evaluated value,and theoretically predicted result.

Activation cross section measurement for （165）~Ho（n，γ）^（166m）Ho and^（151）Eu（n，γ）^（152g）Eu

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玛西斜坡区风城组高含盐致密储集层流体识别

准噶尔盆地玛西斜坡区二叠系风城组发育碱湖沉积的高含盐致密储集层,其油水关系复杂,流体识别难度大。利用岩性扫描测井资料构建饱含盐水地层热中子宏观俘获截面,并利用测井热中子宏观俘获截面与饱含盐水地层热中子宏观俘获截面的差值构建含油性敏感因子,再利用氯元素相对产额与总孔隙度比值构建含盐度敏感因子,将含油性敏感因子与含盐度敏感因子交会形成流体识别图版。实例应用表明,利用该流体识别图版可以对储集层流体性质进行准确判断,为试油选层提供依据。

Neutron capture cross section of ^(169)Tm measured at the CSNS Back-n facility in the energy region from 30 to 300 keV

The capture cross sections of the ^(169)Tm(n,γ)reaction were measured at the back streaming white neutron beam line(Back-n)of the China Spallation Neutron Source(CSNS)using four C_(6)D_(6) liquid scintillation detectors.The background subtraction,normalization,and correction were carefully considered in the data analysis to obtain accurate cross sections.For the resonance at 3.9 eV,the R-matrix code SAMMY was used to determine the resonance parameters with the internal normalization method.The average capture cross sections of ^(169)Tm for energy between 30 and 300 keV were extracted relative to the ^(197)Au(n,γ)reaction.The measured cross sections of the ^(169)Tm(n,γ)reaction were reported in logarithmically equidistant energy bins with 20 bins per energy decade with a total uncertainty of 5.4%-7.0% in this study and described in terms of average resonance parameters using a Hauser-Feshbach calculation with fluctuations.The point-wise cross sections and the average resonance parameters showed fair agreement with the evaluated values of the ENDF/B-Ⅷ.0 library in the energy region studied.

基于白光中子源的^(197)Au中子辐射俘获截面测量及共振参数分析

中子辐射俘获反应在反应堆运行、核装置设计及核天体物理研究中起重要的作用.4πBaF_(2)探测装置有着高时间分辨能力、低中子灵敏度、高探测效率等优点,适合开展中子辐射俘获反应截面数据的测量.中国原子能科学研究院核数据重点实验室建立了伽马全吸收装置(Gamma total absorption facility,GTAF),该装置用28块六棱BaF_(2)晶体和12块五棱BaF_(2)晶体构成了外径25 cm,内径10 cm的球壳,覆盖了95.2%的立体角.利用GTAF在中国散裂中子源Back-n束线上,测量了197Au(n,γ)的反应截面数据.测量数据通过能量筛选、PSD方法、晶体多重性筛选进行了初步本底扣除,随后结合对^(nat)C及空样品的测量数据对本底进行了分析及扣除,获得了197Au俘获反应的产额,利用SAMMY程序拟合得到了^(197)Au在1—100 e V的共振能量、中子共振宽度和伽马共振宽度参数.实验测量结果与ENDF/B-VIII.0数据库符合良好,其共振参数存在一定差异,分析原因可能与GTAF能量分辨率、Back-n的中子能谱测量精度、以及实验本底扣除方法相关,这也是下一步工作的重点.

Monte Carlo simulation for pulsed neutron-neutron logging in fractured and cavernous carbonate formation

The influence of carbonate formation on Pulsed Neutron logging(such as Pulsed Neutron-Neutron logging)is quite different from that of sandstone due to the complexity of reservoir architecture and the development of fracture in carbonate reservoir.To study the factors affecting Pulsed Neutron-Neutron(PNN)logging in carbonate formation,the responses on fracture or cave are simulated by Monte Carlo method,getting the relationships among the macroscopic capture cross section(Σ),the count ratio of the thermal neutron at far spacing and near spacing detectors(RATIO),the fracture porosity,oil-bearing and shale content of fracture.The results show that PNN logging can be used to detect caves,and there exist linear relationships among the macroscopic capture cross section(Σ),the count ratio(RATIO)and the above factors.The research findings in this paper provides theoretical basis for the interpretation and data correction of the PNN logging in carbonate reservoirs.

不同评价核数据库对堆芯物理计算结果有效增殖系数的影响与分析

核数据的准确性影响反应堆安全,在反应堆堆芯物理计算过程中具有重要意义。为了研究不同核数据库对临界计算结果有效增殖系数的影响,基于核数据处理程序NJOY21对国际上最新的5个评价核数据库ENDF/B-Ⅷ.0、JENDL5、JEFF3.3、BROND3.1、CENDL3.2进行制作,选取专门用于核数据检验的119道临界基准模型,利用MCNP6.1开展临界计算。通过统计分析不同核数据库计算结果与基准实验结果的偏差与基准实验不确定性的比值及其三个特征量来判断核数据库对临界计算的影响。结果表明:采用ENDF/B-VIII.0核数据库的临界计算结果准确性更高,其中BROND3.1和CENDL3.2核数据库在临界计算过程中出现了较大误差,通过数据分析发现其主要原因是BROND3.1和CENDL3.2核数据库缺乏热中子散射截面数据S(α,β)。将ENDF/B-VIII.0核数据库中的热中子散射截面数据S(α,β)导入BROND3.1、CENDL3.2核数据库中进行临界模拟,计算结果发生了明显改善。因此,建议在今后的核数据评价工作中尽快完善热中子散射截面数据S(α,β),以提高核数据库在反应堆物理计算过程中的准确性。

脉冲中子衰减τ—Σ图的制作、分析与应用

针对利用脉冲中子衰减数据提取俘获截面会出现信息丢失、计算过程参数复杂变化的问题,提出一种新的分析和处理方法。基于Hough变换理论,脉冲中子衰减谱采用了非常规的ζ—θ方程变换并在Hough空间进行显示。根据脉冲中子衰减数据特征,需要采用Hough空间的图形增强模式进行处理,将Hough空间坐标轴进行转化,生成中子寿命—俘获截面图(τ—Σ图)。对中子寿命—俘获截面图的图形特征与物理意义的关系及其在数据处理过程中的优、缺点进行分析。处理了套后中子衰减饱和度仪器的实测资料,对比中子寿命—俘获截面图法与传统方法提取俘获截面的处理过程和曲线差别,结果表明,采用中子寿命—俘获截面图进行脉冲中子衰减测井资料处理,改进了俘获截面处理过程和结果,可以更有效地进行测井资料质量控制。该方法也可用于其他脉冲中子衰减仪器的资料处理。

γ射线辐照对纤维玻璃性能影响研究

为了探究两种不同元素玻璃伽马辐照的吸收作用,在10MGy剂量水平下,进行了γ射线辐照试验,研究了γ射线辐照后玻璃性能的变化情况,包含对辐照前后的体弹模量、杨氏模量和剪切模量的表征,此外还用紫外-可见-近红外光谱法表征了玻璃的耐辐照性能情况,利用红外光谱研究了玻璃结构的变化情况。实验结果证明,利用中子俘获反应截面设计的新一代耐热耐辐照玻璃,能有效提高玻璃的耐高剂量γ射线辐照性能。

中子照相∑定量测量方法

本文描述了一种利用中子照相进行定量分析的方法,介绍了该方法的基本原理,并应用粒子输运程序MCNP模拟分析样品内部散射中子随样品与探测器之间距离变化对中子成像的影响。为削弱散射中子对中子透射成像图像信息的影响,对穿透样品的厚度进行了定量分析。

Al-B_4C复合材料中子吸收性能研究

利用蒙特卡罗方法和^(252)Cf中子源研究了在准直热中子入射束下,15%~30%(质量分数)碳化硼含量的Al-B_4C复合材料的中子吸收系数和宏观截面。结果表明,Al-B_4C复合材料的中子吸收系数随碳化硼含量增加而增大,相同碳化硼含量的材料其中子吸收系数随厚度的增加按指数规律变化;^(252)Cf中子源测试得到的中子吸收系数比0.0253eV单能热中子计算得到的吸收系数低0.5%~4.3%;Al-B_4C复合材料的宏观截面随着碳化硼含量的增加呈线性递增的关系,而且理想热中子0.0253eV下的递增率(0.97925cm^(-1)/%)大于^(252)Cf中子源构建0~1eV中子下的递增率(0.58537cm^(-1)/%)。

硼中子寿命测井技术应用研究——以现河庄油田为例

胜利油区的现河庄油田,由数个面积较小且地质条件相对复杂的断块组成,目前已开采30多年,层间矛盾较为突出,大部分区块已进入高含水期,水淹严重。硼中子寿命测井技术作为近些年发展起来的一项重要的放射性测井技术,对于油田开发,特别是对于油藏高含水阶段的进一步开采,与其他测井方法相比有着独特的优势。介绍了硼中子寿命测井技术,着重阐述了该项技术在现河庄油田的应用情况,对几口典型井进行了重点剖析,从而为该技术在同类型油田的进一步应用,提供了借鉴。

脉冲中子-中子测井影响因素的数值模拟

利用蒙特卡罗方法建立各种条件下的套管井计算模型,模拟相应的热中子时间谱,进而计算地层宏观吸收截面。模拟结果表明:地层的宏观吸收截面随着孔隙度和含水饱和度的增加而增加,且源距越小、地层水的矿化度和泥质含量越高、套管的尺寸越大、仪器越居中、俘获截面越高的岩性地层条件下,地层的宏观吸收截面值也越大;套管壁厚和水泥环对地层宏观吸收截面没有影响,但套管壁越厚、水泥环厚度越小,热中子总计数越低。利用脉冲中子测井数据确定地层含水饱和度时应对各种影响因素作相应的校正。