A diagrammatic method for the calculation of moments of operators and its application to nuclear spectroscopy

The physical content of the well-known Lanczos method of tridiagonalisation is analysed in the framework of nuclear spectroscopy of low-lying states. The formal calculations are based on diagrammatic methods. Their link with other methods and their possible use in other fields of spectroscopy are briefly considered.     

Laser spectroscopy — Recent results and prospects for lighter nuclei

Atomic physics methods have provided important information about the electromagnetic properties of the nuclear ground states. In recent years the experimental effort has been directed towards optical high resolution spectroscopy of very high sensitivity, giving access to short-lived nuclides very far from stability. A few of these new techniques based on collinear laser spectroscopy are presented with their latest results. They are suitable for an extension of the experiments to the region of lighter nuclei.     

应用光核反应计算μ原子中的核极化效应

近年来,瑞士保罗谢勒研究所的CREMA合作组通过测量$\mu$氢原子兰姆位移显著提升了质子半径的测量精确度。然而这一新实验结果与已知质子半径标准值(CODATA)相差5.6个标准差,被称为质子半径之谜,受到众多物理学家的关注。受此启发,CREMA合作组在不同的$\mu$原子中展开了一系列兰姆位移光谱的测量实验。他们计划从这些$\mu$原子的测量中得到轻核(包括$^{2,3}{\rm{H}}$,$^{3,4}{\rm{He}}$)的电荷半径。除了对光谱测量精度的要求外,轻核半径的实验精度当前仍被一项理论输入量限制:核极化效应对$\mu$原子光谱的修正。核极化效应体现了$\mu$子与原子核进行双光子交换中对核的虚激发,进而对$\mu$原子能谱产生高阶修正。因此,这一效应与光核反应以及康普顿散射直接相关。核极化效应对兰姆位移的修正可通过计算光核吸收截面以及虚光子康普顿振幅的求和规则而得到。本工作运用第一性原理的核结构计算方法,研究了$\mu$原子中的核极化效应。通过结合现代核力模型与超球简谐基展开多体方法,计算了一系列与核极化相关的光核反应及康普顿散射求和规则。这一理论研究为从$\mu$原子光谱测量中对核半径的精确提取提供了关键性的理论输入。     

用于核物理研究的精密激光谱技术的发展和展望

原子核基本性质（自旋、质量、寿命、磁矩、电四极矩和电荷半径等）与原子核的内在结构密切相关,是检验和发展原子核理论模型的重要依据。实验上可以通过多学科交叉的精密激光谱技术测量原子核外电子的超精细结构和同位素移位,来模型独立地提取原子核的自旋、磁矩、电四极矩和电荷均方根半径等多个核物理参量。这些基本性质的系统测量可以用于探索不稳定原子核中展现出来的新奇的物理现象与规律。近年来,为了测量产额更低的丰中子核的基本性质,激光谱技术不断更新和发展,以实现高分辨、高效率测量。本文详细介绍了激光谱测量的基本原理以及由此发展起来的用于不稳定原子核结构研究的各类互补的激光谱学技术,如共线激光谱（高分辨率低灵敏度）、在源激光谱（高灵敏度低分辨率）、共线共振电离谱（高分辨率高灵敏度）等激光谱技术,以及在不同核区的测量优势和局限。最后结合我国正在发展和规划中的新一代放射性核束装置,讨论精密激光谱技术在国内的发展以及在核物理研究中的应用。     

氧化物纳米材料表面结构与性质的固体核磁共振波谱研究

氧化物纳米材料的多种应用与其表面结构和性质密切相关.近年来,固体核磁共振波谱在相关研究中提供了关键信息.本综述总结了近期发展的、以固体核磁共振波谱为主的两种表征氧化物纳米材料表面结构和性质的方法,包括表面选择的同位素标记¹⁷O核磁共振波谱与动态核极化表面增强核磁共振波谱,并对氧化物纳米材料的固体核磁共振波谱研究的发展趋势进行了展望.     

材料化学分析的物理方法(Ⅰ)

材料的化学信息是理解科学、工程与技术领域各种过程、机制和材料行为的最基本要素，材料研究的第一步是要确定材料的化学，包括构成材料的原子的种类、分布以及具体的化学态等内容，任何具有元素特征的物理信息，包括原子量、电子的能级、原子核自旋，甚至局域的电子态密度等都可以用来做材料的化学分析，化学信息由来自材料本身的或用作探针的电子、光子、离子或中性原子携带，相应的分析技术包括X射线光电子能谱、俄歇电子谱、核磁共振、特征X射线分析、二次离子质谱、能量损失谱、溅射中性粒子质谱，各类离子散射谱以及扫描隧道显微学方法等等，文章对上述各种分析方法的物理原理、仪器以及应用等逐一做扼要的介绍。     

核物理与核探测、核分析技术的应用

文章概要介绍了随着核物理研究发展起来的辐射和粒子探测的原理、方法和主要技术,举例介绍了相关核物理与核探测、核分析的典型技术及其在高精度测量和医学中的广泛应用,如活化分析技术、穆斯堡尔谱学、核磁共振技术、加速器质谱技术、核医学成像、同步辐射技术、中子散射分析、放射性示踪技术等等.     

Scientific opportunities in nuclear resonance spectroscopy from source-driven revolution

From the beginning of its discovery the Mössbauer effect has continued to be one of the most powerful tools with broad applications in diverse areas of science and technology. With the advent of synchrotron radiation sources such as the Advanced Photon Source (APS), the European Synchrotron Radiation Facility (ESRF) and the Super Photon Ring-8 (SPring-8), the tool has enlarged its scope and delivered new capabilities. The popular techniques most generally used in the field of materials physics, chemical physics, geoscience, and biology are hyperfine spectroscopy via elastic nuclear forward scattering (NFS), vibrational spectroscopy via nuclear inelastic scattering (NRIXS), and, to a lesser extent, diffusional dynamics from quasielastic nuclear forward scattering (QNFS). As we look ahead, new storage rings with enhanced brilliance such as PETRA-III under construction at DESY, Hamburg, and PEP-III in its early design stage at SLAC, Stanford, will provide new and unique science opportunities. In the next two decades, x-ray free-electron lasers (XFELs), based both on self-amplified spontaneous emission (SASE-XFELs) and a seed (SXFELs), with unique time structure, coherence and a five to six orders higher average brilliance will truly revolutionize nuclear resonance applications in a major way. This overview is intended to briefly address the unique radiation characteristics of new sources on the horizon and to provide a glimpse of scientific prospects and dreams in the nuclear resonance field from the new radiation sources. We anticipate an expanded nuclear resonance research activity with applications such as spin and phonon mapping of a single nanostructure and their assemblies, interfaces, and surfaces; spin dynamics; nonequilibrium dynamics; photochemical reactions; excited-state spectroscopy; and nonlinear phenomena.     

Prospects for emission Mössbauer spectroscopy in chemical investigations

Emission Mössbauer spectroscopy is a radiochemical method for investigating materials and the consequences of nuclear transformations taking place in them. Isotopes are traditionally used as structural probes, and the sensitivity of the method is 2–3 orders of magnitude higher than that of absorption Mössbauer spectroscopy. The elements of Mössbauer isotopes with parent nuclei that undergo electron capture or a converted isomeric transition (i.e., lead to high Auger ionization) are the best-studied elements. The electron processes that accompany ionization and their effect on the state of daughter Mössbauer atoms in qualitatively different compounds, from elementary oxides, superconductors, insulators and magnetics to sophisticated bioorganic complexes, are considered.     

From radop to laser spectroscopy and back

The paper reviews some techniques in optical spectroscopy of short-lived nuclei, their results regarding nuclear moments and isotopic shift, and their relation to the work of Professor K. Sugimoto.     

Developing DNP/Solid-State NMR Spectroscopy of Oriented Membranes

Dynamic nuclear polarization (DNP)/solid-state nuclear magnetic resonance (NMR) spectroscopy bears great potential for the investigation of membrane-associated polypeptides which can often be produced only in small amounts and which need to be ‘diluted’ in lipid bilayer environments to adopt or maintain their functional structure. Here we present investigations using biradicals, such as TOTAPOL and bTbK, for solid-state NMR signal enhancement using DNP in the context of lipid membranes. By transferring polarization from electron to nuclear spins using microwave irradiation signal enhancement factors of up to 13 are obtained with TOTAPOL and up to 17 with bTbK. The possible reasons why these factors are below those obtained in glassy samples of bulk solvents (40–60 under similar conditions) are evaluated and discussed. In order to further ameliorate the enhancement factors the physico-chemical characteristics of TEMPOL, TOTAPOL, bTbK, and bCTbK, such as their partitioning between hydrophilic and hydrophobic solvents or their stability under different environmental conditions are presented. Finally, having provided proof-of-concept that DNP/solid-state NMR measurements can be performed with oriented membrane samples work in progress is presented on the development of a flat-coil probe for DNP/solid-state NMR experiments on oriented membranes.     

Nuclear spins of ionized phosphorus donors in silicon

We demonstrate the coherent control and electrical readout of ionized phosphorus donor nuclear spins in (nat)Si. By combining time-programed optical excitation with coherent electron spin manipulation, we selectively ionize the donors depending on their nuclear spin state, exploiting a spin-dependent recombination process at the Si/SiO(2) interface, and find a nuclear spin coherence time of 18 ms for the ionized donors. The presented technique allows for spectroscopy of ionized-donor nuclear spins and enhances the sensitivity of electron nuclear double resonance to a level of 3000 nuclear spins.     

基于不稳定核基本性质测量的原子核结构研究

精密激光谱学是通过测量核素原子光谱的超精细结构和同位素移位来研究原子核的基本性质,为原子核自旋、磁矩、电四极矩及电荷均方根半径的确定提供了一种模型独立的测量方式。这些原子核基本性质的测量,能够比较精确地描述原子核微观结构的演化。近年来,随着放射性束流装置的发展,产生远离β-稳定线的丰中子/丰质子核素成为可能,也进一步促进了高分辨和高灵敏度的激光谱技术更加广泛的应用。简单介绍了基于放射性核素超精细结构的激光谱学测量原理,并通过几个经典实例来回顾近年来激光谱学在原子核奇特结构研究领域的独特贡献。主要通过分析几个重要核区原子核的基本性质,结合大尺度壳模型、ab initio理论、密度泛函理论等,来探索丰中子核中展现出来的一些新的奇特现象,如晕结构、幻数演化、形状共存等。High-precision laser spectroscopy technique is used to determine the ground state properties of exotic nuclei by probing its electronic hyperfine structure and isotope shift. It provides a model-independent measurement of nuclear spin, magnetic moment, electric quadrupole moment and charge radii. These nuclear parameters can be used to investigate the nuclear structure evolution and the nuclear shapes. With the development of accelerators and isotope separators, exotic isotopes far from β stability became accessible experimentally, which enhanced the capability of the laser spectroscopy technique being applied in the field of nuclear physics. A brief introduction to experimental principle is given, followed by a review of several typical examples for the experimental investigations in the different regions of nuclear chart. This aims to demonstrate the contributions of ground state properties measurement by using laser spectroscopy technique to the nuclear structure study of exotic isotopes. This discussion involves several different nuclear theory models in order to interpret the exotic phenomena observed in the neutron-rich isotopes, such as halo structure, shell evolution, shape coexistence and so on.     

Use of IR Absorption Laser Spectroscopy at Nuclear Fuel Cycle Plants: Problems and Prospects (Review)

The main stages of the nuclear fuel cycle from extraction of uranium ores to disposal of radioactive waste resulting from the processing of spent nuclear fuel were briefly analyzed. A list of the most probable radioactive substances and toxic chemicals that can be part of emergency emissions at each stage of the nuclear fuel cycle was composed. The basic physical principles of local and remote IR absorption laser technologies for detecting radioactive substances and toxic chemicals in the atmosphere for solving some unique problems of environmental monitoring were considered. The analytical potential of the currently most effective laser technologies for atmospheric monitoring at nuclear fuel cycle plants based on the achievements of diode laser spectroscopy, cavity ringdown laser spectroscopy, and optoacoustic laser spectroscopy using diode and quantum-cascade lasers was discussed. Current trends in the development of laser technologies for atmospheric monitoring in different IR spectral ranges were analyzed.     

Diffusion of insoluble carbon in zirconium oxides

The diffusion coefficient of insoluble carbon in zirconium oxides has been obtained for the temperature range of 900–1000°C. There are no published data on the diffusion of insoluble impurities; these data are of current interest for the diffusion theory and nuclear technologies. Tracer atoms 13C have been introduced into oxides by means of ion implantation and the kinetics of their emission from the samples in the process of annealing in air has been analyzed. The measurements have been performed using the methods of nuclear microanalysis and X-ray photoelectron spectroscopy. The diffusion activation energy is 2.7 eV and the carbon diffusion coefficient is about six orders of magnitude smaller than that for oxygen self-diffusion in the same systems. This result indicates the strong anomaly of the diffusion properties of carbon in oxides. As a result, zirconium oxides cannot be used in some nuclear technologies, in particular, as a material of sources for accelerators of short-lived carbon isotopes.     

On-line nuclear orientation study of184Au

The¹⁸⁴Au→¹⁸⁴Pt decay, studied on-line with the UNISOR facility at HHIRF, is discussed. Gamma-ray and conversion-electron spectroscopy of¹⁸⁴Pt as well as on-line nuclear orientation measurements of¹⁸⁴Au were done. A new low-lying level scheme of¹⁸⁴Pt is proposed. Two coexisting bands with different deformations and their respective γ-vibrational bands are established. Internal conversion coefficients for interband transitions between states with the same spin are extracted from the spectroscopy measurements. The relative E0 contents of the transitions are determined by combining internal conversion coefficients with E2/M1 mixing ratios deduced from gamma-ray anisotropies measured from oriented nuclei.     

光谱分析方法在同位素检测中的研究和应用进展

同位素在核工业为主的各种工业生产中受到广泛的关注,并推动着地质学、材料科学、化学等相关学科的发展。近年来,基于光谱分析原理的同位素分析方法的开发逐渐受到关注。虽然多接收杯电感耦合等离子体质谱（MC-ICP-MS）、热电离质谱（TIMS）和气体同位素质谱（IRMS）等质谱技术是同位素分析的标准方法,但是这些质谱方法通常需要复杂的样品前处理流程以及频繁的仪器维护。光谱分析方法在这些方面有着自身独特优势,甚至可以满足现场实时快速的同位素分析,并在核工业同位素分析和传统稳定同位素分析领域已经取得了日益广泛的应用。随着光谱仪器关键部件和数据处理方法的进一步发展,极大地改善了光谱法同位素分析的性能（灵敏度、分辨率和精密度）,使光谱分析方法被逐渐开发并应用于环境和地质同位素分析领域。综述了光谱分析方法在同位素分析（定量或定性）领域的主要进展,从光谱分析原理的角度归类为发射光谱（原子发射、分子发射、拉曼光谱）和吸收光谱（原子吸收、分子吸收）两大类。着重讨论了光谱法进行同位素分析的基本原理、发展历程以及重要进展,简述了与质谱法相比的优缺点。针对仍然有待突破的技术难点,展望了光谱法应用于同位素分析的发展前景。该综述可为光谱分析方法在同位素检测中的发展方向提供重要参考。     

小波分析及神经网络方法在核物理及核工程中的应用

介绍了小波分析和神经网络方法在核物理及核工程领域的应用现状。 分别对小波分析及神经网络方法的基本原理进行了介绍, 详细讨论了小波变换中的多分辨分析方法在γ能谱平滑以及核电站设备监测等方面的应用, 讨论了连续小波变换在γ能谱分析、 粒子种类鉴别以及核反应堆安全监测等领域的应用。 同时, 还详细介绍了神经网络方法在以上各领域的发展现状。 最后, 展望了两种方法在核安全检测、 核辐射防护以及核电站实时监控等领域的发展趋势。 Applications of wavelet analysis and neutral networks in the field of nuclear physics and engineering are reviewed. The principle of these two methods are introduced briefly, and then the applications of multiresolution analysis technique in the smoothing of γ ray spectroscopy, and in nuclear power plant monitoring are discussed in detail. Applications of the continuous wavelet analysis method in γ ray spectroscopy analysis, in particle identification , and in nuclear reactor safety monitoring are also talked over. In addition, the applications of neutral networks in above fields are introduced. Finally, the trends of the future development for these two methods are prospected.     

Electron paramagnetic resonance spectroscopy of Cr 3+ in hexagonal Cs 2 NaGaF 6 crystals

Powder samples of hydrothermally grown Cr 3+ -doped Cs 2 NaGaF 6 crystals have been investigated with electron paramagnetic resonance spectroscopy at X - (9.5 v GHz) and Q -band (34 v GHz). Analysis of the spectra clearly demonstrates that there are two distinct Cr 3+ centres in the Cs 2 NaGaF 6 crystal, having nearly identical g factors, but differing largely from the viewpoint of their zero field splitting. By using the 53 Cr hyperfine spectra observed with electron nuclear double resonance spectroscopy, it is deduced that these centres have opposite signs for the zero field splitting. The spectroscopic properties of the Cr 3+ centres in the isostructural Cs 2 NaGaF 6 and Cs 2 NaAlF 6 crystals are compared and discussed.