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绝缘体上硅(SOI)硅微剂量测量系统可以通过测量中子和伽马混合辐射场的线能谱来获取不同类型辐射的剂量当量贡献。本文根据SOI硅微剂量探测器物理设计,采用GEANT4软件建模对Cf-252中子和伽马混合辐射场及Co-60伽马辐射线能谱测量进行蒙特卡罗模拟,并进一步分析了SOI探测器转换层对伽马线能谱测量的影响。结果表明,SOI硅微剂量探测器能够区分中子和伽马的剂量贡献,并且伽马线能谱峰值随着转换层厚度发生变化,有可能利用该特性实现不同贯穿深度下伽马辐射剂量贡献的测量。模拟分析结果可为SOI硅微剂量探测器设计及应用提供参考。 相似文献
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采用CRY宇宙射线模拟软件包,获取不同测量条件下μ子的特征信息,研究不同条件下宇宙射线中μ子的通量、能谱、角分布等特征规律。研究结果表明:太阳活动极大时会使μ子通量降低;地磁场的影响使得赤道附近的μ子通量比极地地区要小且能谱蓝移;海拔升高则会显著增大μ子通量,但总体能量均值降低。模拟结果与相关实验结果具有很好的一致性。 相似文献
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利用D-T中子对氧化钍圆柱装置进行了辐照。样品直径为30 cm、厚度为15 cm。在不同的布局状态下,采用芪晶体闪烁体基于反冲质子法对1 MeV~15 MeV中子能谱进行了实验测量;基于反冲电子法对中子辐照下和辐照后的0.5 MeV以上伽马能谱进行了测量。对能谱中的分布规律、与布局状态的关系进行了比对分析。 相似文献
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伽马暴偏振探测仪POLAR-2主要用于伽马射线暴瞬时辐射的高精度偏振测量。为了提高偏振测量精度和样本,需要获取伽马暴的高精度方向和能谱信息。POLAR-2中能谱探测器BSD载荷将实现10~2 000 keV能量范围内的伽马暴能谱测量且具有在轨快速触发和定位的功能。设计了基于FPGA的数据传输和计算的触发软件测试系统,可以在没有探测器输入的情况下,通过以太网传输测试数据,验证BSD触发算法的可行性和性能。当给出相邻光子的间隔时间和每个光子的能量后,通过该系统可以得到不同时标下各能量段的信噪比和光变,与模拟计算的光变和信噪比进行比对之后,可以在BSD早期的设计中验证该触发算法的准确性。测试结果表明,该系统满足设计要求,可以方便地在地面验证和调整触发算法。 相似文献
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《核电子学与探测技术》2017,(5)
采用宇宙射线生成软件包CRY,获取不同测量条件下μ子的特征信息,研究各种条件对宇宙射线中μ子的通量、能谱、角分布等特征的影响规律。结果表明:太阳活动极大时会使μ子通量降低;地磁场的影响使得赤道附近的μ子通量比极地地区要小且能谱蓝移;海拔升高则会显著增大μ子通量,但总体能量均值降低。 相似文献
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固体径迹探测器广泛应用于科学和技术方面,CR39是其中使用很频繁的一种塑料探测器。由于电子和伽马光子在CR39中的碰撞截面很小,远小于中子、质子或其他离子的碰撞截面,因此可认为固体径迹探测器CR39对电子和光子不响应,而仅对中子、质子或其他离子响应,这给CR39在实验中的应用带来很大优点。在超短超强脉冲激光与等离子体相互作用的实验中,会产生大量的强伽马射线、热电子或超热电子,而在有些实验如超短超强脉冲激光加速产生高能质子束的研究中,需单独对质子束的通量、角分布、能谱等参数进行详尽的测量。 相似文献
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5×1024×10高速核辐射能谱获取系统研制 总被引:2,自引:1,他引:2
在磁约束聚变实验装置的物理实验中,为了测量高温等离子体箱射的某特定能量区域的X射线或其他核箱射能谱的时、空分布,需要在托卡马克的板向和环向方向布置多台X射线探测器,每次放电可同时获得数十个能谱,为了不牺牲能谱中的重要信息(如线辐射).以及能量分辨的需要,要求每个能谱有1024道,每个谱采集的时间分为:40、80、160、240ms,可自由设定,每道容量16位,每次放电可同时获得50个能谱,可扩展到80个能谱。 相似文献
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基于强流氘氚中子源科学装置HINEG设计了一套快中子照相准直屏蔽系统。采用中子输运设计与安全评价软件系统SuperMC和ENDF/B-Ⅶ.0数据库计算了准直中子束的中子能谱及注量率、γ射线能谱及注量率、直射中子注量率与γ射线注量率比值(φd/φγ)、直射与散射中子注量率比值(φd/φs)、准直束中子注量率的不均匀度等特性参数,并采用MCNP5程序进行了对比验证。研究了准直屏蔽系统的内衬材料、尺寸等对特性参数的影响规律,并通过优化获取了最优设计方案。计算结果显示,在同等计算条件下,SuperMC计算结果与MCNP计算结果相对偏差小于1%,准直屏蔽系统的φd/φγ为50.1,φd/φs为5.7,在Φ30 cm视野范围内的中子注量率为4.80×107 cm-2•s-1,其中直射中子注量率为4.09×107 cm-2•s-1,中子注量率不均匀度为5.8%,满足快中子照相对准直束特性参数的要求。 相似文献
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Libin LV 《等离子体科学和技术》2019,21(9):95301-57
In this study, we present a simulation study of artificial field-aligned irregularities (AFAI) to calculate the scattering coefficient considering a Gaussian autocorrelation function for the wave number spectrum of the density fluctuation. By analyzing variations in the scattering coefficient under different ionospheric backgrounds, the optimal range of the heating frequency was found, which is about 0.9–1 times the critical frequency of the F2 layer. This is especially noticeable as when the heating frequency varies from 0.5 times to 0.9 times of the critical frequency, the scattering coefficient increases by 6.8–16.2 dB. These results should be useful for optimizing the heating frequency in the future artificial field-aligned scattering (AFAS) transmission applications at middle and low latitudes. 相似文献
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《核技术(英文版)》2015,(5)
A direct incident fluence measurement method based on amorphous silicon electronic portal imaging device(a-Si EPID) has been developed for pretreatment verification of intensity-modulated radiation therapy(IMRT).The EPID-based incident fluence conversion method deconvolves EPID images to the primary response distribution based on measured lateral scatter kernels in the EPID detector using Conjugate Gradient algorithm.The primary response is converted to the incident fluence based on measured fluence conversion matrix which corrects for off-axis position dependence of the a-Si EPID response and the "horn" beam profile caused by flatting filter. To verify feasibility and accuracy of this method, square fields of various sizes and two IMRT plans were delivered. The dose distributions computed based on EPID-derived incident fluence were compared with the measurement data. For all square field sizes except the smallest field(2 cm), the mean dose differences in cross-line dose profiles were within 1% excluding the penumbra region, and gamma passing percentages with a 2%/2 mm criterion were about 99%. For two IMRT plans, the least gamma passing percentage for all eight IMRT fields was 98.14% with 2%/3 mm criteria. It can be concluded that our direct EPID-based incident fluence conversion method is accurate and capable of being applied to pretreatment dose verification in clinical routines. 相似文献
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This paper examines the effects of gamma and neutron heating and pressure wave propagation on the core response during an instantaneous loss of condenser vacuum transient without scram (ATWS) in a BWR. By incorporating the gamma and neutron heating, which contribute about 3% of the total power to the moderator, into the transient thermal-hydraulic analysis, the peak power was found to be 35% lower compared with the case with no direct heating. The incorporation of the two-dimensional radial and axial variations of reactivity feedbacks and moderator density into the transient analysis led to a lower power prediction than the one-dimensional model. The pressure surge was examined by a computer program based on the method of characteristics. The pressure rise calculated by this new code was found to be in good agreement with experimental data, while the results of similar calculations done by computer code RELAP4, which is based on finite differencing of the flow equations, were 50% lower. 相似文献
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For low single-pass absorption of ion cyclotron range frequency (ICRF) wave in the EAST plasma cavity modes are expected to be excited between the low field side (LFS) antenna and the hybrid cut-off layer. The toroidal spectrum for D(H) minority heating scenarios in EAST is modeled by using FELICE(Finite Elements Ion Cyclotron Emulator), a full wave code based on plane-stratified geometry. The excitation of cavity modes is studied. The methods for suppressing cavity modes are also discussed, to increase the efficiency of minority ion heating. 相似文献
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A simple analytical model is presented which indicates that the ratio of heating power densities of two different materials, irradiated under the same conditions inside a reactor core, can be estimated from material properties only. The developed approximate method allows simplifying the measurement technique of a number of samples from different materials by performing measurement of only one sample. The latter is a primary result of the proportionality between the heating and the thermal neutron flux for samples irradiated under the same conditions. This is confirmed by measurements in the Greek Research Reactor (GRR1) showing that the temperature of materials irradiated at various positions of a vertical core channel due to all heating mechanisms follows the spatial variation of thermal neutron flux. Validation by the numerical 3D gamma heating code GHRRC developed in NCSR Demokritos shows that the conclusions of the simple analytical method apply also for the total heating by all gammas in the core. A model is also presented for the estimation of heating by elastic neutron scattering. Furthermore, a methodology is suggested for the estimation of the temperature and the heat power deposited on materials irradiated during normal reactor operation, based on in-pile temperature measurements performed at low reactor power levels. 相似文献
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慢衰减型闪烁体(NaI(Tl)、CsI(Tl)等)探测器经过前放输出的脉冲信号具有较长的上升时间,造成电荷在收集的过程中出现严重的弹道亏损。在后续脉冲成形中为了降低弹道亏损对能量分辨率的影响,一般采用较宽的成形平顶来增加电荷的收集时间。但在高辐射粒子注量率的场合下,由于慢衰减型闪烁体输出的脉冲堆积严重,采用传统的滤波成形方式获得的脉冲计数率和能量分辨率明显降低。为解决此问题,本文提出了一种以数字反褶积为核心的数字快成形算法。该算法可去掉慢衰减型闪烁体探测系统的衰减电流拖尾,获得一理想的冲激脉冲电流,然后再通过滤波成形为一窄脉冲,并彻底消除弹道亏损的影响。通过对~(137) Csγ源测量,使用传统成形算法的能谱测量系统在成形时间为1.5μs时,其光电峰能量分辨率为6.99%,计数率为68 000s~(-1);而使用数字快成形系统,在相同情况下获得6.37%的能量分辨率,计数率可达102 000s~(-1)。因此数字快成形算法可有效地修复在高辐射粒子注量率下,窄脉冲成形引起的信号变形和拖尾,从而提高了脉冲堆积甄别能力。 相似文献