【学术视频】ASOS2019 | 美国国家标准与技术研究院Yuri Ralchenko

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图 | Yuri Ralchenko

题   目：Nuclear radii, x-ray polarization, and everything in between: spectroscopy of highly-charged ions with the NIST EBIT报告人：Yuri Ralchenko单   位：National Institute of Standards and Technology Gaithersburg MD, USA时   间：2019-06-24地   点：复旦大学

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报告摘要

Over the last 25 years the Electron Beam Ion Trap (EBIT) at the National Institute of Standards and Technology (NIST) established itself as one of the world’s primary tools for analysis of light emission from highly - charged ions. A vast collection of precise dispersive and non - dispersive spectroscopic instruments allows accurate measurements of spectra from ions with a charge as high as 70 over more than four orders of magnitude in photon wavelengths or energies. In addition, the in - house developed advanced collisional-radiative (CR) modeling of the non-Maxwellian EBIT plasma provides the indispensable theoretical support for spectra interpretation. 
We will present an overview of the recent spectroscopic experiments on the NIST EBIT. In particular, the EUV measurements and precise multi-configuration Dirac-Hartree-Fock and relativistic many-body perturbation theory calculations of the difference in nuclear charge radius of Xe isotopes of highly charged Na-like ions will be discussed in detail. Then, the analysis of polarization characteristics from x-ray spectra of dielectronic satellites and excitation - induced lines in Li - and He - like Ar will be presented. The measured polarization parameters will be compared with the calculations based on the density matrix approach and the large - scale CR modeling of magnetic - sublevel population kinetics. 
We will also report the first results of broadband x - ray experiments with the newly deployed NIST EBIT X-ray TES (NEXT) spectrometer. NEXT houses 192 individual microcalorimeters with high x - ray collection efficiency and energy resolution of about 4 eV (the measurement energy range is from a few hundred eV to~15 keV). The very first spectra from highly - charged mid - and high-Z elements show high precision and excellent performance of NEXT. Again, comparisons with the CR simulations that are instrumental for spectra analysis and interpretation will be presented and discussed. 

个人简介

Yuri Ralchenko is Group Leader of the Atomic Spectroscopy Group at NIST. His research is focused on spectroscopy of highly-charged ions, analysis of various atomic processes in plasmas with emphasis on accurate modeling of plasma population kinetics, development of Internet atomic databases, and other aspects of plasma spectroscopy. This work includes collisional-radiative modeling of various plasmas (including non-Maxwellian and transient ones), production and assessment of accurate atomic data (energies, oscillator strengths, collisional cross sections, etc.), and development of methods and standards for dissemination of scientific data.Dr. Ralchenko is a Fellow of the American Physical Society. He was also awarded the 2015 NIST Judson C. French Award for "establishing the world's premier resource for atomic reference data, relied upon for everything from nuclear forensics to Hubble Space Telescope data analysis." He is an Editorial Board member of several scientific journals, has authored over 110 scientific publications, and has been a speaker at numerous national and international conferences.

会议简介

ASOS研讨会系1983年始办于瑞典隆德大学，随后每三年一届，在美国、荷兰、法国、加拿大、英国、比利时、巴西等多个国家的大学或科研机构举办。本着“将原子分子数据研究者与应用者凝聚在一起”的宗旨，一方面邀请研究原子结构与原子碰撞辐射特性相关课题的原子物理学家来介绍最新进展，另一方面邀请天体物理学家和实验室等离子体物理学家来综述他们最新关注的科学问题及其需要的原子数据。历经了36年的发展，逐步成为等离子体光谱领域具有国际影响力的盛会，成为该领域专家学者一个良好的学术交流与合作平台。第十三届研讨会在上海举行，由复旦大学主办。

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