BRISOL谱仪关键技术研究

HI-13串列加速器升级工程在线同位素分离器（BRISOL）需对同质异位素进行分辨,谱仪设计质量分辨率为20 000,是很高的技术指标,对离子源、高压、分析磁铁、四极透镜等设备均有很大的挑战。本文详细介绍了BRISOL谱仪关键技术及其测试结果。能散对谱仪的质量分辨率影响较大,BRISOL谱仪设计采用异能大小铁结构消除能量色散。离子源采用表面离子源,并采用三电极引出系统,中间电极电压可调用以优化束流品质,优化后离子束RMS发射度好于3.8 πmm•mrad。分析磁铁采用表面线圈进行磁场垫补,垫补后积分场均匀性好于3.5×10^-5。为修正像差,大分析磁铁安装了β线圈和γ线圈,同时,在分析磁铁前后共设置了4台电六极透镜。     

光学渡越辐射在电子束能谱测量上的应用

论述了用光学渡越辐射对强流短脉冲束团的能谱进行测量的理论和方法。探讨了利用单膜装置、双膜装置或多膜装置产生的光学渡越辐射进行束流能谱测量的方法，并针对２０ＭｅＶ电子感应直线加速器能散为０．５％的电子束能谱测量作了一些计算以得到部分装置的设计参数。计算表明：应用渡越光栅谱仪选择合适的膜片厚度及间距，对于给定的电子能谱，可以得到大的能量接受度和好的能量分辨率。然而，要用大量的膜片是困难的，而且还有许多影响多膜渡越辐射能谱仪的实际问题需要讨论。     

CSNS费米斩波器样机中子狭缝包设计

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...     

合肥光源注入器条带检测器的设计与计算

根据合肥光源升级改造的要求,为进行合肥光源注入器的束流位置、发射度和能散的非拦截测量,设计了新的条带束流位置检测器（BPM）和八电极束流能散检测器（BESM）。计算了条带BPM和八电极BESM通过电信号提取x2－y2以及灵敏度的公式。通过条带电极的时域频率分析、阻抗匹配等计算确定了两个检测器的具体物理参数。在CSTmicrowavestudio中按照计算的物理结构进行建模仿真,得到了电极间的耦合且考虑了电极耦合对灵敏度的影响。计算了条带BPM的位置分辨率,符合设计要求。     

正电子寿命谱仪的最佳分辨率

能窗的选择对正电子寿命谱仪的分辨率有决定性的影响。本文描述了一种获得谱仪最佳分辨率的方法。将正电子寿命谱仪的可工作能区分成42个小块。测量每小块能区的分辨率(FWHM)、计数率和峰位“走动”。从中选出分辨率小、计数率高和“走动”小的好能区。能窗是由若干个最佳小能区组成。谱仪分辨率的理论计算值和实验测量值符合得很好。     

水平散射几何中子反射谱仪的三盘斩波器设计

为提高水平散射几何中子反射谱仪分辨,希望谱仪前端的中子斩波器能斩出脉冲强度大水平发散度较小的中子脉冲束流,采用新设计的三斩盘斩波器模型,运用Mcstas程序软件考察了不同物理参数下三盘斩波器的中子斩波特性.获得了特定物理条件下相关物理参数对束流强度和发散度的影响关系曲线.计算结果可为水平散射几何中子反射谱仪中三盘斩波器的设计及物理参数的选择提供理论依据.     

束流能散度和传输管道孔径变化对束流尾场效应的影响

采用双粒子模型，讨论了束流能散度和传输管道孔径变化对由第一个宏粒子产生的束流尾场的影响。并将所得的计算尾场效应的公式，变换成六维传输矩阵的形式，使之能用于束流传输系统的模拟计算。     

BRIF—ISOL主磁铁的电磁力和形变计算

BRIF-ISOL系统的质量分辨率的设计值为20000。在此情况下，要求ISOL的磁铁磁场的均匀度应达到万分之一，然后经垫补实现十万分之一。磁场的均匀度和磁铁的设计加工有关，而磁铁在重力和磁力下的变形也会带来磁场分布的不均匀。ISOL束流光学系统包括7块二极磁铁。其中，偏转半径最大的主磁铁半径为2．5m，极面宽度46cm，最大极面磁感应强度0．5T。我们采用数值计算的办法计算了磁极面在电磁力和自身重量的影响下的形变。     

中子三轴谱仪分辨率的计算与分析

描述了中子三轴谱仪分辨率函数的计算方法,计算分析了中子波矢、准直器水平发散度、谱仪布局及能量和动量转移对分辨率函数的影响.谱仪分辨率随着入射波矢增大而降低,随着准直器水平发散度的减小而提高,谱仪最高能量分辨率能达到23μeV,计算值与实验测量和模拟计算结果符合得很好;谱仪布局只改变分辨率椭球在散射平面的方向,而不会影响...     

TMSR白光中子源能量分辨率函数的模拟研究

白光中子源及飞行时间谱仪的能量分辨率函数描述了谱仪装置测量中子能量的分辨率与所测中子的能量之间的函数关系。能量分辨率函数用于中子共振截面测量实验数据分析，对确定共振峰参数至关重要。本工作利用Geant4蒙特卡罗工具包构建了TMSR白光中子源的中子产生靶系统模型，模拟了中子在靶系统内由产生到溢出靶系统的整个物理过程，获得了不同能群中子从产生到溢出的时间分布。基于RPI能量分辨率函数形式，对时间分布进行拟合分析，获得了一套合适的参数，用于确定TMSR白光中子源飞行时间谱仪的中子能量分辨率函数。     

Ion-optical design of the high-resolution mass separator for the Japanese Hadron Project

An ion-optical design of the JHP-ISOL is presented. This separator consists of a beam guidance system, a main magnetic separator stage and an electrostatic energy focusing stage. This separator is to be coupled with a heavy-ion linac for post-acceleration of mass separated ions up to 6.5 MeV/u. The design goal of the separator is to realize a mass resolving power of R_M = 20000 (basal) at a transmission approaching 100% with the initial phase space of ± 0.2 mm × ± 20 mrad.     

Antiproton-proton mass comparison with a radio-frequency mass spectrometer

The experiment aims at the reduction of the upper limit on a hypothetical CPT violation in the antiproton-proton system. A radio-frequency mass spectrometer (RFMS) has been designed and built to make the comparison of the charge to mass ratios of and p by measuring the ratios of the cyclotron frequencies of and H⁻ ions. At present, the RFMS is installed on-line to the LEAR facility at CERN. The resolving power has been found to be close to 3 × 10⁵ and it still could be improved. A decelerating system (RFQ) has been installed in order to decelerate antiprotons from 2 MeV to 200 keV and to match as well as possible the acceptance of the spectrometer. It is presently under test and data taking should take place in 1992.     

Ion-optical correction elements for on-line mass separators

To adjust on-line mass separators, variable magnetic or electrostatic multipoles are most desirable. Such elements were built and subsequently included in the ISOLDE-3 on-line mass separator at CERN. In first tests a mass resolving power m/†m > 10 000 (FWHM) was achieved, which allowed the isobaric separation of ³⁷Ca from ³⁷K using a tungsten-surface ionization source.     

Latest advances in soft X-ray spectromicroscopy at SSRF

The BL08U1 A beamline is established as a sophisticated platform at Shanghai Synchrotron Radiation Facility(SSRF), taking advantage of its high spatial resolution( 30 nm) and high energy resolving power(10 000),for studying properties of solid, liquid, gas, film and other forms of materials at sub-micron scale. In this paper,we present a review on newly implemented techniques, such as total electron yield(TEY), dual energy contrast imaging, nano-CT, soft X-ray excited optical luminance(SXEOL), and coherent diffraction imaging(CDI)under development. Several research cases in nanomaterials, environmental science and biology are presented to demonstrate capabilities of the beamline.     

扫描电子显微镜结合热电离质谱测定单微粒中铀同位素比值

单微粒铀同位素分析是核保障环境监测技术的重要手段。作为现阶段应用最可靠且广泛的微粒分析技术之一,裂变径迹-热电离质谱(FT-TIMS)技术需依赖反应堆辐照,分析步骤繁琐,效率较低。扫描电子显微镜结合热电离质谱(SEM-TIMS)在保持原有TIMS的高测量精密度的同时,由扫描电子显微镜结合X射线能量色散谱仪(SEM-EDX)完成含铀微粒的寻找和鉴别,由微操作系统进行微粒转移,缩短了分析流程,提高了分析效率。本文应用建立的SEM-TIMS分析方法对已知同位素组成的单分散铀氧化物标准微粒进行了测量,测量结果与其标称值一致。     

Germanium ?-Ray Spectrometers

Potential uses of the Ge(Li) diode detector as part of a spectrometer system for space experimentation would include identification of energy sources and determination of the composition of materials. In laboratory experiments its greatest application is in low-energy nuclear physics, mainly (n, ?) reaction studies. The primary advantage in its present use is energy resolving capability. In future applications, as energy resolution is maintained close to the observed limit for the detector, increased attention must be given to optimization in terms of geometry. Further improvements are needed in the mechanical design of such systems, especially for experiments in space.     

北京放射性核束装置在线同位素分离器的研制

北京放射性核束装置在线同位素分离器（BRISOL）采用100 MeV、200 μA回旋加速器提供的质子束打靶产生中、短寿命放射性核束,进行在线分析后供物理用户使用,其质量分辨率好于20 000。BRISOL装置现已建成,并开展了氧化镁、氧化钙靶的在线实验,在线产生了³⁷K⁺、³⁸K⁺、²⁰Na⁺、²¹Na⁺等多种放射性核束。本文详细介绍该装置的研制及运行情况。     

Development of a helicon-wave excited plasma facility with high magnetic field for plasma-wall interactions studies

The high magnetic field helicon experiment system is a helicon wave plasma(HWP)source device in a high axial magnetic field(B_0)developed for plasma–wall interactions studies for fusion reactors.This HWP was realized at low pressure(5?×?10~(-3)?-?10 Pa)and a RF(radio frequency,13.56 MHz)power(maximum power of 2 k W)using an internal right helical antenna(5 cm in diameter by 18 cm long)with a maximum B_0of 6300 G.Ar HWP with electron density~10~(18)–10~(20)m~(-3)and electron temperature~4–7 e V was produced at high B_0 of 5100 G,with an RF power of 1500 W.Maximum Ar~+ion flux of 7.8?×?10~(23)m~(-2)s~(-1)with a bright blue core plasma was obtained at a high B_0 of 2700 G and an RF power of 1500 W without bias.Plasma energy and mass spectrometer studies indicate that Ar~+ion-beams of 40.1 eV are formed,which are supersonic(~3.1c_s).The effect of Ar HWP discharge cleaning on the wall conditioning are investigated by using the mass spectrometry.And the consequent plasma parameters will result in favorable wall conditioning with a removal rate of 1.1?×?10~(24)N_2/m~2 h.     

Spectrometer of hard X-ray imager payload onboard the ASO-S mission

A spaceborne hard X-ray spectrometer, composed of an array of 99 scintillation detectors and associated readout electronics, has been developed for the hard X-ray imager(HXI). The HXI is one of the three payloads onboard the advanced space-based solar observatory(ASO-S), which is scheduled to be launched in early 2022 as the first Chinese solar satellite. LaBr_3 scintillators and photomultiplier tubes with a super bialkali cathode are used to achieve an energy resolution better than 20% at 30 keV.Further, a new multi-channel charge-sensitive readout application-specific integrated circuit guarantees high-frequency data acquisition with low power consumption. This paper presents a detailed design of the spectrometer for the engineering model of the HXI and discusses its noise and linearity performance.