软X射线能谱仪与透射光栅谱仪测量结果的对比

对软X射线谱仪和透射光栅谱仪的测量结果进行了对比。它们的回推谱形大致符合,只是透射光栅谱仪的复原谱的N带相对于O带太小。其原因可能是X射线CCD受到靶室油沾污,在表面形成了碳膜,对N带吸收较多。经过对透射光栅谱进行吸收补偿后,两种谱仪的复原谱基本一致。     

高效高分辨率大面积透射光栅谱仪特性的理论分析

为提高透射光栅谱仪对激光等离子体Ｘ光源的收集效率的光谱分辨同铲高分辨率大面积航向光栅光谱仪。该谱仪由轮胎镜、无支撑高线密度光栅和软Ｘ光ＣＣＤ相机组成。应用部分相干光衍射理论,研究了该谱仪成偈面上的光强分布和光谱分辩率,在１．４～１２ｎｍ的摄谱范围内光 人发辨率为０．０５ｎｍ,与实验符合得很好。由于其高效率,该谱仪尤其适用于超短飞秒脉冲激光产生等离子体的实验研究。     

新型软X-射线透射光栅光谱仪的研制

研制了一种新型的由带前置轮胎镜成像系统、高密度透射光栅和软Ｘ光ＣＣＤ相机等组成的软Ｘ射线光谱仪,摄谱范围为０．５－１．５ｎｍ,光谱分辩为为０．０５ｎｍ。光谱仪没有像散,实现了点对点成像。由于其高效率激光系统产生的等离子体Ｘ光谱,特别适合于超短飞秒强激光脉冲产生的等离子体的研究。     

ICF实验软X光能谱的基函数解谱法

 惯性约束聚变实验中,14通道软X光能谱仪是测量软X射线能谱、等效积分温度和辐射能流时间过程的重要诊断设备。基函数法是还原能谱分布的一种常用方法。通过对双峰谱形的还原,对不同类型基函数的选择、基函数参数的设置和求解方法等影响解谱的因素进行了比较分析。根据大量算例的结果,使用优化后的基函数和求解方法对实际测量辐射谱进行了计算,并与透射光栅谱仪的测量结果进行了比较。结果显示,根据谱仪通道响应选择三次样条的节点,能够较好还原软X射线的能谱。     

管靶X射线辐射输运初步研究Ⅱ.实验测量与分析

从实验上研究了X射线在管靶中辐射输运情况.给出两种分解靶：源靶、输运靶.源靶可得到X射线输运的输入条件,输运靶是近似一维X射线输运管道,对其测量可得到输运的结果;给出两种分解靶由软X射线谱仪、平响应XRD和透射光栅谱仪(配X射线CCD)测量的结果,并对实验结果进行分析;最后对输运管道内的等离子体膨胀问题进行了讨论. 关键词：     

应用于PTS装置的多通道X射线二极管阵列谱仪

介绍了用于PTS（初级实验平台）装置上Z箍缩内爆物理实验诊断的多通道X射线二极管（XRD）阵列谱仪原理、性能及主要参数,给出了根据实验结果回推光源辐射能谱的解谱算法。在PTS装置上开展的首轮物理实验中,使用多通道XRD阵列谱仪对Z箍缩产生的等离子体源辐射的软X射线能谱、功率、能量进行测量,给出了测量结果及分析,并与其他参试设备测量结果进行了比较。关键词: Abstract: Key words: ;     

超短强激光辐照Ar喷气靶的X射线发射

利用带差分抽运系统的高效高分辨率软Ｘ射线大面积透射光栅光谱仪,对超短强激光脉冲辐照下氩气体靶的软Ｘ射线发射特性进行了光谱诊断。测量了氩气１２ｎｍ￣３５ｎｍ范围内的Ｘ射线发射光谱,并观察到Ｘ射线发射强度随喷气气压的增加而增加。     

软X射线自支撑闪耀透射光栅

软X射线自支撑闪耀透射光栅或临界角透射光栅是美国麻省理工学院为满足国际X射线天文台X射线光栅谱仪的科学要求而提出的一种新型衍射光栅,它集中了透射和反射光栅的优点,同时避免它们的缺点.文章对软X射线自支撑闪耀透射光栅的概念、基本原理、制作工艺进行了综述,介绍了美国麻省理工学院的光栅研制工作进展和文章作者的初步研究结果.     

错位双光栅色散元件设计及衍射效率研究

设计了一种错位双光栅色散元件,与条纹相机耦合实现了0.1~5keV范围X射线时间分辨谱的测量.该色散元件由2 000lp/mm和5 000lp/mm两块子光栅在空间错位排布而成,低密度光栅测量低能段软X射线(100~1 000eV),高密度光栅测量中能段软X射线(1 000~5 000eV),通过空间错位实现能谱拼接.在同步辐射源上使用单色能点对其进行标定,获得了错位双光栅衍射效率的实验结果.根据光栅的结构特性,结合标定结果与严格耦合波分析理论,计算得到了100~5 000eV能区光栅的绝对衍射效率曲线,并给出了错位双光栅的解谱方法.该错位双光栅能够有效提升透射光栅谱仪的性能,为高温等离子体诊断提供宽谱X射线时间分辨谱定量测量.     

黑洞靶X光产生机制实验研究

本文报导了黑洞靶Ｘ光产生机制实验研究。实验采用波长为１．０５３μｍ，能量为３００－７００Ｊ／束，脉宽为６００－１０００ｐｓ的高斯型激光脉冲。利用三台亚千Ｘ光能谱仪，三台软Ｘ光针孔相机、一台软Ｘ光透射光栅谱仪和十个平响应亚千Ｘ射线二极管对十余种结构、尺寸腔靶实验进行测量。实验给出了腔靶发射Ｘ光的空间分辨像、时间过程、光谱结构及空间角分布测量结果。通过分析，基本弄清了黑洞靶Ｘ光产生机制。     

Accurate reconstruction of soft X-ray energy spectrum in detector response matrix

In this paper, we report the design of a Monte Carlo simulation for the energy spectrum measurement system based on the ladderabsorption method. Herein, the detector response matrix can be calculated using the detector responses to several monochromatic X-ray beams. A novel soft X-ray spectrum unfolding method based on the two-step reverse iteration(TSRI) algorithm is applied to acquire the primary spectrum. This paper provides examples of the use of TSRI, and the unfolded energy spectra for the soft Xray beams show excellent agreement with the references. The unfolded energy spectra obtained using the TSRI exhibit better accuracy than those obtained from the commonly used unfolding code GRAVEL.     

Output functions and fractal dimensions in dynamical systems

We present a novel method for the calculation of the fractal dimension of boundaries in dynamical systems, which is in many cases many orders of magnitude more efficient than the uncertainty method. We call it the output function evaluation (OFE) method. We show analytically that the OFE method is much more efficient than the uncertainty method for boundaries with D<0.5, where D is the dimension of the intersection of the boundary with a one-dimensional manifold. We apply the OFE method to a scattering system, and compare it to the uncertainty method. We use the OFE method to study the behavior of the fractal dimension as the system's dynamics undergoes a topological transition.     

软X光Dante谱仪的平滑解谱算法及其在Z箍缩诊断中的应用

 针对自行研制的8通道Dante谱仪,提出了一种使用B样条曲线进行平滑解谱的算法,并用黑体谱对其进行了验证。计算结果表明：新算法与使用矩形函数解谱的算法相比,对能谱轮廓与总辐射强度的反演精度均有明显提高。给出了“阳”加速器氩气喷气Z箍缩实验的测量波形,由8通道Dante谱仪的测量结果解谱得到的软X光峰值辐射功率和总能量分别为40.5 GW和851 J,与软X光功率计经修正后的测量结果相一致。     

Mössbauer spectroscopic evidence on the heme binding to the proximal histidine in unfolded carbonmonoxy myoglobin by guanidine hydrochloride

The unfolded heme structure in myoglobin is controversial because of no chance of direct X-ray structure analyses. The unfolding of carbonmonoxy myoglobin (MbCO) by guanidine hydrochloride (GdnHCl) was studied by the Mössbauer spectroscopy. The spectra show the presence of a sort of spectrum in the unfolded MbCO, independent on the concentration of GdnHCl from 1 to 6 M and the increase of the fraction of unfolded MbCO, depending on the GdnHCl concentration. The isomer shift of the iron of heme in the unfolded MbCO was identified to be different from that of the native MbCO as the globin structure in Mb collapses under the unfolded conditions. This result and the existing related Mössbauer data proved that the heme in the unfolded MbCO may remain coordinated to the proximal histidine.     

Unfolding the fast neutron spectra of a BC501A liquid scintillation detector using GRAVEL method

Accurate knowledge of the neutron energy spectra is useful in basic research and applications. The overall procedure of measuring and unfolding the fast neutron energy spectra with BC501A liquid scintillation detector is described. The recoil proton spectrum of 241Am-Be neutrons was obtained experimentally. With the NRESP7 code, the response matrix of detector was simulated. Combining the recoil proton spectrum and response matrix, the unfolding of neutron spectra was performed by GRAVEL iterative algorithm. A MatLab program based on the GRAVEL method was developed. The continuous neutron spectrum of ²⁴¹Am-Be source and monoenergetic neutron spectrum of D-T source have been unfolded successfully and are in good agreement with their standard reference spectra. The unfolded ²⁴¹Am-Be spectrum are more accurate than the spectra unfolded by artificial neural networks in recent years.     

The results of disorder on the empty states in GeTe as seen by x-ray absorption

The Te L₁ and L₃ X-ray absorption spectra for GeTe in amorphous and crystalline form are presented. The spectra have been unfolded for the broadening effects of the inner levels employed. Significant effects of disorder are observed and are assigned to changes in the empty d-states, while the states with p-symmetry appear to be unaffected.     

Antineutrino energy spectrum unfolding based on the Daya Bay measurement and its applications

The prediction of reactor antineutrino spectra will play a crucial role as reactor experiments enter the precision era.The positron energy spectrum of 3.5 million antineutrino inverse beta decay reactions observed by the Day a Bay experiment,in combination with the fission rates of fissile isotopes in the reactor,is used to extract the positron energy spectra resulting from the fission of specific isotopes.This information can be used to produce a precise,data-based prediction of the antineutrino energy spectrum in other reactor antineutrino experiments with different fission fractions than Day a Bay.The positron energy spectra are unfolded to obtain the antineutrino energy spectra by removing the contribution from detector response with the Wiener-SVD unfolding method.Consistent results are obtained with other unfolding methods.A technique to construct a data-based prediction of the reactor antineutrino energy spectrum is proposed and investigated.Given the reactor fission fractions,the technique can predict the energy spectrum to a 2% precision.In addition,we illustrate how to perform a rigorous comparison between the unfolded antineutrino spectrum and a theoretical model prediction that avoids the input model bias of the unfolding method.     

The effects of shielding around the source on neutron energy spectra

The knowledge of neutron energy spectra contributes to unambiguous identification of neutron sources in the fields of nuclear safeguards and nuclear non-proliferation. Since a real scenario situation includes the presence of shielding around the source, we have investigated the influence of the potential shielding surrounding the source on the shape of energy spectra for a few neutron sources. We have applied the maximum-likelihood, expectation–maximisation (MLEM) method with one-step-late (OSL) algorithm for neutron spectra unfolding. The pulse height distributions used in the unfolding procedures were simulated with the high accuracy by using the MCNP-PoliMi code based on the Monte Carlo method. A possibility to identify the shielded neutron sources by using the unfolding method was examined with two continuous-in-energy sources, such as ²⁵²Cf and ²⁴¹Am–Be in source-shielding configurations with lead (Pb) and polyethylene (PE) blocks. The results of calculations have shown that the identification of ²⁵²Cf and ²⁴¹Am–Be sources with 2.5 cm of Pb and PE shield can be achieved successfully by using the MLEM method with the OSL algorithm. However, the unfolded results for ²⁵²Cf and ²⁴¹Am–Be sources with 10 cm of PE shield significantly deviate from the reference spectra and the sources cannot be correctly identified on the basis of their unfolded energy spectra.     

激光等离子体非平衡X射线发射谱理论研究

在平均离子模型的基础上,发展了一个计算离子组态概率分布的有效方法,称为统计方法.根据激光靶耦合程序模拟给出腔靶等离子体状态条件,研究1.06μm激光金等离子体的非平衡离子组态分布和X射线发射谱特性.得到与实验谱相同的能带范围,并得出在激光等离子体中多电子同时处于激发态的离子组态对X射线发射的贡献不能忽略的结论. 关键词：     

Comparison of unfolding approaches for monoenergetic and continuous fast-neutron energy spectra

Proton-recoil detectors offer the possibility to unfold fast-neutron energy spectra of various sources. However, quantifying the confidence of the unfolding methodology is a complex task. In this paper, we present a comparative analysis of the maximum-likelihood, expectation-maximization (MLEM) method and one-step-late (OSL) method for neutron energy spectra unfolding. The analysis is performed on Monte Carlo simulated data for several monoenergetic neutron sources and continuous-in-energy ²⁵²Cf, ²⁴¹Am–Be and ²⁴¹Am–Li neutron sources. The results obtained for the monoenergetic neutron spectra show that both unfolding methods provide results that are in good agreement with the reference data. Very good agreement between the unfolded and the reference data is achieved for ²⁵²Cf, ²⁴¹Am–Be, and ²⁴¹Am–Li neutron spectra by using the OSL method. In the paper it is demonstrated that the MLEM and OSL methods can be applied to accurately unfold the simulated pulse-height distributions for organic liquid scintillation detectors. Comparative analysis between the two unfolding methods has shown that the OSL method has superior unfolding performance than the MLEM method.