共查询到17条相似文献,搜索用时 140 毫秒
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《核技术》2018,(12)
带宽限制中子斩波器是中国散裂中子源上飞行时间中子散射谱仪不可缺少的关键设备之一,谱仪获得的中子能谱波段范围由带宽斩波器决定,其主要原理是通过转盘的机械式阻挡来对中子束流进行斩波,选择到达样品的中子波长范围,从而起到降低背底、提高信噪比的作用。本文介绍了带宽限制中子斩波器的基本原理及其设计要求,重点阐述了带宽限制中子斩波器系统的设计方法,提出了斩波器系统配置布局的基本原则,并给出了带宽斩波器各物理参数的计算公式。带宽斩波器的配置数量应满足谱仪背底要求,去除背底的斩波器应放置在束线前端并使谱仪所需波段的中子无损失通过,带宽选取的斩波器则尽可能放置在束线后端。另外,满足同相位、同转速、同开口角和转动方向相反等条件的双盘斩波器可以在一定程度上提高中子通量。本文的工作可为中国散裂中子源二十台中子散射谱仪斩波器系统的物理设计提供指导和参考。 相似文献
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费米斩波器是中子非弹性散射谱仪上对中子束流进行单色化的关键设备,其性能影响谱仪的分辨率和计数率。费米斩波器的核心部件是由中子吸收材料和透明材料层叠而成的中子狭缝包,通过狭缝包的高速旋转选出多个单一波长的脉冲中子。中国散裂中子源(China Spallation Neutron Source,CSNS)正在研制费米斩波器样机,基于样机研制要求设计了三种典型的狭缝包,通过使用McStas软件,模拟验证了设计方案的可行性。模拟结果表明:1)在0.02~0.50 nm的波长范围调整三种狭缝包的转速能够实现2%~10%的分辨率,中子衰减率和狭缝包透射率均能满足要求;2)三种狭缝包在600 Hz工作频率下的最佳入射波长各为0.165 nm、0.040 nm、0.023 nm,分别用于不同的工作波长范围;3)在分辨率较好的长波段,狭缝包可降速使用以提高中子通过率。该研究为CSNS费米斩波器的样机研制提供了物理参数,为下一步的样机狭缝包性能测试,以及非弹性散射谱仪费米斩波器中子狭缝包的设计提供了参考依据。 相似文献
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介绍了一种新型中子剂量当量仪的电子学系统的设计,该系统由电源电路、放大器电路、脉冲幅度甄别电路和仪器控制电路等部分组成.该系统能够满足该新型中子剂量仪的功能要求,能够实现该新型中子剂量仪的信号采集、结果计算和仪表控制等功能. 相似文献
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为了能探测高能中子,获得中子能谱信息,设计了一套基于塑料闪烁体光纤和多路复用技术的中子探测系统。利用梯度尺寸结构的阵列化探头感应中子入射的能量和方向。多路复用数据采集及读出单元接收探测器输出信号并产生触发信号,经处理后上传给上位机。数据采集及读出系统通过以太网实现实时通信。上位机程序基于LabWindows/CVI软件平台开发,实现数据读取与保存以及采集系统运行状态参数信息的实时显示。通过中子模拟源进行了现场测试,结果表明,设计的中子探测系统满足设计要求,能实现中子能量与入射方向的测量。 相似文献
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Masayoshi Ono Sunao Okamoto 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1984,1(1):146-158
Characterization of a wide band neutron chopper, which can provide a wide range of wavelengths of slow neutrons in a pulse, was performed by computer calculations to obtain the optimum value of the coefficient of neutron utilization. This was done after detailed examinations of neutron burst shapes and transmission probabilities for various shapes of slits of the rotor with the shapes of the slits determined in accordance with the neutron trajectories in the rotating rotor. In the calculations, the divergence angles of incident neutrons are fully taken into account. A wide band chopper designed on the basis of the characterization to provide polychromatic pulsed neutrons in the range of 2–10 A for neutron small angle scattering (NSAS) has been installed at Kyoto University Research Reactor. The manufacture of the rotor and the experimental tests for the rotor have satisfactorily been performed. As an application of the chopper to NSAS, precipitation phenomena in the Ti-Nb alloy aged at 643 K were successfully examined as a function of aging time by means of the time-of-flight technique. In the NSAS, scattering patterns were simultaneously provided for a wide range of the scattering vector. It has been demonstrated that the coefficient of neutron utilization by the present chopper is improved by about 57 times at and 12 times at 5 Å, respectively, in comparison with the coefficient for a conventional chopper. 相似文献
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就中子物理飞行时间技术对脉冲中子发生器的需要,对中国原子能科学研究院600kVns脉冲中子发生器的聚束和切割性能的某些参量进行分析和计算,将结果与实验进行比较,并把它们用于脉冲化装置的调试 相似文献
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L. Szentmiklósi Zs. Révay T. Belgya 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,263(1):90-94
Modulating neutron beams with a beam chopper enables the investigation of time-dependent processes following neutron capture, such as emission of decay-gamma-radiation from short-lived nuclides. For this purpose, a redesigned beam chopper and controller electronics have been recently installed at the PGAA facility of the Budapest Research Reactor. The new electronics provides accurate timing and better control of routing of the signals. The upgraded instrumentation is capable of recording the events in the beam-on and beam-off phases in parallel. Simplified formulae were derived to relate the areas of prompt- and decay peaks to the partial γ-ray production cross-sections. Finally, preliminary results obtained with Ag- and Na-containing targets are presented. 相似文献
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P. Junphong D. Suwannakachorn S. Singkarat 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(24):2895-2900
The first drift-tube neutron generator in Thailand, developed during 1980s under the support by the International Atomic Energy Agency (IAEA), was a 150 kV deuteron accelerator-based 14 MeV fast neutron generator. The accelerator was featured by a nanosecond pulsing system consisting of a beam chopper in combination with a beam buncher. Following the rapid development of ion beam technology and increasing needs for materials applications in the laboratory, the accelerator has been upgraded and modified to a large extent into a medium-energy ion-accelerator for time-of-flight Rutherford backscattering spectrometry (TOF-RBS) applications. The modification of the accelerator included the changing of the ion source, the accelerating tube and the mass-analyzing magnet, the upgrading of the pulsing system, and the installation of a TOF-RBS detecting system. The new accelerator is capable of supplying a 400-keV He-ion beam with ns-pulses for nano-layered materials analysis. This paper provides technical details of the modification. 相似文献
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中子光响应函数是液体闪烁体探测器的重要参数,准确的光响应函数和探测阈值是精确确定中子探测效率的基础。近年来,专门用于液体闪烁体中子探测器的高集成度新型电子学插件(Mesytec公司的MPD-4)广泛应用于中子探测系统中,该电子学插件集成了脉冲高度(PH)、脉冲形状甄别(PSD)和恒比定时(CFD)测量功能,且1个NIM插件即可实现4路探测器的同时测量。对于同一中子探测器,利用这一电子学系统与传统电子学系统对中子的光响应函数进行了实验比对,结果表明,两套系统得到的中子光响应函数具有明显的差异。因此,在使用MPD-4电子学系统进行中子探测的实验中,需对光响应函数进行重新标定。 相似文献
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Laura R. Skubal David B. Chojnowski Raymond Ziegler 《Nuclear Engineering and Design》2008,238(1):130-134
To neutron choppers at Oak Ridge National Laboratory's Spallation Neutron Source will stop prompt pulses of high-energy neutrons outside the target moderator. Choppers are cooled internally by recirculated distilled water maintained at 15 °C. Numerous metallic components are used to fabricate the choppers and cooling system; water contacts many of these components, establishing a corrosion cell. To chopper system corrosion products were investigated analytically. Results showed elevated concentrations of soluble and precipitated iron and copper in cooling water. A chemical-based corrosion strategy was implemented in a To chopper system during mechanical tests not involving system irradiation. Chemical analyses showed that a chemical corrosion inhibitor stopped system corrosion for 6 months after its introduction. Corrosion cessation was beneficial, as mechanical tests were performed without interruption from precipitate wear on mechanical parts, flowmeter blockage, or a decrease in heat transfer capabilities. Aqueous chemical changes occurring in the cooling system upon inhibitor addition are discussed. 相似文献
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铑自给能探测器(RSPND)输出电流信号的慢响应特性严重影响反应堆内中子注量率的实时测量,不利于反应堆的控制和安全管理。采用反函数计算或各种补偿方法改进其响应特性,有利于RSPND的使用。本文研究了前向差分变换法、后向差分变换法、阶跃响应不变法及双线性变换法等4种数字处理算法,有效缩短了铑自给能探测器输出信号的响应时间,时间常数缩短到5 s以内。通过数字实验系统,验证了算法的正确性,为该探测器用于反应堆内中子注量率测量的快速响应提供了可行性。 相似文献