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散裂中子源进展汇报 January 15, 2019
中国散裂中子源和极化中子技术
童欣
中科院高能所
散裂中子源进展汇报 January 15, 2019
Self-introduction
散裂中子源进展汇报 January 15, 2019
Outlines
▪ 中子散射简介
▪ 中国散裂中子源概况
▪ 极化中子散射
▪ 两个例子▪ 极化中子成像▪ 弱相互作用的测量
散裂中子源进展汇报 January 15, 2019
Study of MaterialsOur Society and cultrue depends on materials, macroscopic properties and microscopic properties
散裂中子源进展汇报 January 15, 2019
Study probes for microstructures
Light : Infrared spectroscopyRaman spectroscopy
Electrons : Electron spectroscopyScanning electron microscopeTransmission electron microscope
X-ray : X-ray DiffractionX-ray absorption spectroscopySmall angle X-ray scattering
Can also use Neutrons
散裂中子源进展汇报 January 15, 2019
中子 vs X射线
中子: 原子核 (强相互作用,~fm)unpaired 电子 (磁)
X-射线:电子 (电磁波)
中子: ~10-2m
X-射线:~10-5m
和物质相互作用 穿透深度
散裂中子源进展汇报 January 15, 2019
Neutrons vs. X-rays!
Neutrons allow easy access to atoms that are usually unseen in X-ray Scattering
Chatterji, Neutron Scattering from Magnetic Materials (2006)
散裂中子源进展汇报 January 15, 2019
• Neutral
• Penetrating, probe
nuclei
• Non-destructive
• Magnetic moment
• Magnetic fluctuations
and domains
• Magnetization density
• Magnetic excitations
• Can be polarized
Properties of Neutrons
散裂中子源进展汇报 January 15, 2019http://www.nobelprize.org/nobel_prizes/physics/laureates/1994/illpres/neutrons.html
1994 Nobel Prize in Physics -- Shull and Brockhouse
散裂中子源进展汇报 January 15, 2019
Sources of neutrons
• Natural sourcesRadioactive elements, e.g., U, CfLifetime ~ 15minutes
• ProcessesFissionFusionOther nuclear reactions
• Man-made Neutron sourcesNuclear reactor sourceSpallation source
散裂中子源进展汇报 January 15, 2019
裂变反应堆
• 链式反应• 连续中子束• 2-3个中子/裂变• ~180MeV/中子(热能)• 全世界30座+
散裂中子源
• 无链式反应• 脉冲型中子束• 30-40个中子/质子• ~30MeV/中子(热能)• 全世界仅4座
Reactors and Spallations
散裂中子源进展汇报 January 15, 2019
Reactors and Spallations
中国散裂中子源
散裂中子源进展汇报 January 15, 2019
Outlines
▪ 中子散射简介
▪ 中国散裂中子源概况
▪ 极化中子散射
▪ 两个例子▪ 极化中子成像▪ 弱相互作用的测量
散裂中子源进展汇报 January 15, 2019
2000年7月 向国家科技领导小组提交的“中国高能物理和
先进加速器发展目标”提出建设散裂中子源
2005年7月 国务院科教领导小组原则批准散裂中子源项目
2007年2月 科学院与广东省签订共建散裂中子源协议,落户东莞
2008年9月 国家发改委批复项目建议书
2011年2月 国家发改委批复可行性研究报告
2011年5月 初步设计报告批复
2011年9月 开工报告批复,工期6.5年
2011年10月 工程奠基仪式
2011年9月~2016年7月 设备加工与制造
2012年5月~2016年8月 土建工程
2014年10月~2017年9月 安装与测试
2017年8月 质子打靶成功获得第一束中子2017年11月 首轮加速器和靶站谱仪的联合调试,功率达到10kW
2018年3月 工程达到全部验收指标,对用户试开放
2018年4月 第一篇用户实验科学成果文章在Nano Energy发表
2018年8月 通过国家验收
散裂子中子源工程重要里程碑
14
散裂中子源进展汇报 January 15, 2019
一期建设 – 基本信息
散裂中子源进展汇报 January 15, 2019
主要技术指标 一期
质子束功率 (kW) 100
脉冲重复频率 (Hz) 25
靶站数 1
束流平均流强 (A) 62.5
束流能量(GeV) 1.6
RCS注入能量(MeV)
80
谱仪数量 3
直线加速器
靶站
谱仪
快循环
同步加
速器
根据《国家发展改革委关于散裂中子源国家重大科技基础设施项目可
行性报告的批复》,主要建设1台80MeV负氢离子直线加速器、1台
1.6GeV快循环同步加速器、2条束流输运线、1个靶站、3台中子谱仪
及配套设施和土建工程。
一期建设 – 建设内容
散裂中子源进展汇报 January 15, 2019
LINAC Building RCS Building
Target and Experiment Halls
散裂中子源进展汇报 January 15, 2019
直线隧道:直线加速器安装完成
环隧道:快循环同步加速器安装完成
一期建设 – 加速器
散裂中子源进展汇报 January 15, 2019
靶站包括靶体、慢化器反射体、氦容器、屏蔽体等。屏蔽体系统中子束线开
关总成共20套,分布于靶站南北两侧扇形区域内。
一期建设 – 靶站
2017年7月底靶站屏蔽与中子束线开关完成安装与调试
散裂中子源进展汇报 January 15, 2019
通用粉末衍射谱仪
多功能反射仪 小角散射仪
一期建设 – 谱仪
散射腔、样品腔安装完成
散射腔、样品腔安装完成
散射腔、样品腔安装完成
散裂中子源进展汇报 January 15, 2019 21
国家重大科技基础设施中国散裂中子源工程顺利通过国家验收,投入正式运行。历经6年半的紧张建设,中国散裂中子源作为我国首台散裂中子源,粤港澳大湾区首个国家重大科技基础设施,按指标、按工期、高质量地完成了工程建设任务,综合性能进入国际同类装置先进行列,将正式对国内外各领域的用户开放。
一期建设 – 国家验收 (2018年8月23日)
散裂中子源进展汇报 January 15, 2019
20条中子通道,一期工程建造3台中子谱仪,目前在同时建造7台中子谱仪
22
中国散裂中子源谱仪规划图
散裂中子源进展汇报 January 15, 2019
通用粉末衍射仪
• 测量粉末样品• 测量原子之间间距• 测量磁结构• 温度:2 K - 1600 K• 磁场:9 T• 压强:5 GPa• 其它原位测量
Energy Storage Materials 16 (2019) 354-363
该新型高容量富锂正极材料电化学性能优于常见大部分富锂材料体系,常用的X射线粉末衍射很难精确定量分析该材料的结构、组份以及锂离子分布情况,因此采用中子粉末衍射实验来获取更多精确的材料结构信息。
散裂中子源进展汇报 January 15, 2019
Outlines
▪ 中子散射简介
▪ 中国散裂中子源概况
▪ 极化中子散射
▪ 两个例子▪ 极化中子成像▪ 弱相互作用的测量
散裂中子源进展汇报 January 15, 2019
• 自旋 1/2
• 带有磁矩• 可以被极化
中子的磁性及自旋,极化中子
散裂中子源进展汇报 January 15, 2019
The use of polarized neutrons
➢ Study Magnetism▪ Skyrmion
▪ Muhlbauer, et al., Science 323 915-919, 2009
▪ Spin density
▪ Lazpita, et al., PRL 119 155701, 2017
▪ Topological insulator
▪ Katmis, et al., Nature 533, 513-516, 2016
➢ Manipulation of neutron spins▪ Spin-Echo spectrometer
▪ Gooben,et al., PRL 115 148302, 2015
▪ Larmor Diffraction
▪ Pfleiderer, et al., Science 316 1871, 2007
➢ Separation of coherent / incoherent scattering▪ Arbe, et al., PRL 117 185501, 2016
➢ Fundamental physics➢ Neutron electric dipole moment
➢ Weak interaction
➢ Quantum phenomena
➢ Many more..
散裂中子源进展汇报 January 15, 2019
My 10-year tenure at ORNL as Polarization Scientist
➢Polarized 3He program▪ One of the best SEOP programs
▪ The best in-situ 3He program
➢Polarized neutron instrumentation and development▪ Reflectometer
▪ Triple-axis Spectrometer
▪ Wide angle Spectrometer
▪ Diffractometer
▪ Small angle neutron scattering
➢Polarized neutron imaging program
➢Other New neutron techniques
Polarized neutron scattering is the only technique that can
unambiguously separate magnetic scattering from nuclear scattering
散裂中子源进展汇报 January 15, 2019
Spallation Neutron Source
High Flux Isotope Reactor
橡树岭国家实验室(ORNL)的中子源装置
散裂中子源进展汇报 January 15, 2019
• Polarizing monochromators (HB1, HYSPEC)
➢ Usually Heusler alloy (Cu2MnAl)
➢ Using preferential Bragg diffraction
➢ Can only work with Monochromatic beam
• Polarizing filters
➢ Usually polarized 3He
➢ Using preferential absorption cross
section
➢ Good for polarizing large wavelength band,
divergent neutron beams
• Supermirrors (MAGICS, FNPB, NSE)
➢ Very efficient, broad-band polarizers
➢ Using perfect reflection
➢ Disadvantage is that small angular beam
divergence required
How to polarize neutrons
3He CellUnpolarized
Neutron Beam
Polarized
Neutron Beam
散裂中子源进展汇报 January 15, 2019
➢GE180 glass
➢3He
➢N2
➢Rb & K
Alkali atom
electron spin
3He atom
nuclear spin
Polarizing the cells – Spin Exchange Optical Pumping
散裂中子源进展汇报 January 15, 2019
Outlines
▪ 中子散射简介
▪ 中国散裂中子源概况
▪ 极化中子散射
▪ 两个例子▪ 极化中子成像▪ 弱相互作用的测量
散裂中子源进展汇报 January 15, 2019
Spin rotation in magnetic field B, length s, v = velocity of neutrons
Setup:
= = = . .v v
L
path
st B ds B
( )0
( , )
1( , ) ( , ) exp( ) 1 cos ( , )
2
a
path
I x y
I x y I x y ds x y = − +
N. Kardjilov, et al, Nature Physics 4, 399-403, (2008), W. Treimer, et al., Phys. Rev. B 85 184522 (2012)
Polarized Neutron Imaging
散裂中子源进展汇报 January 15, 2019
❖ How does Polarized Neutron Imaging work?
➢ Larmor precession
➢ Transform magnetic field distribution into neutron polarization shift
❖ Why use Polarized Neutron Imaging?
➢ Sensitive to magnetic field distribution
❑ Contrast between magnetic/non-magnetic material
❑ Measure magnetic field distribution
❑ Characterize magnetic structure
Polarized Neutron Imaging
散裂中子源进展汇报 January 15, 2019
Polarized Neutron Imaging Setup
散裂中子源进展汇报 January 15, 2019
Polarized neutron imaging measurements – Cylindrical coils
散裂中子源进展汇报 January 15, 2019
While warming
Fe3Pt: TC depends on whether it is in structurally or disordered state but ranges from 300-400 K. TC = approx. 450 K (177C). The sample is a good single crystal.
(a)
(d)
(b)
(e)
(c)
(f)
425 K 430 K 435 K
440 K 445 K 450 K
Polarized Neutron Imaging of Fe3Pt sample
散裂中子源进展汇报 January 15, 2019
Polarized Neutron Imaging Fancy Pictures
散裂中子源进展汇报 January 15, 2019
❖ Operating with both monochromatic (2.58Å) and polychromatic neutron
❖ Supermirror Polarizer
❖3He neutron spin filter analyzer
❖ ~90% neutron polarization
❖ 350 µm resolution
❖ Controlled magnetic guide field
❑ Solenoid❑ Permanent magnets❑ Nutator (Rotatable
Electro-magnets)
B
极化中子成像装置
散裂中子源进展汇报 January 15, 2019
Visualizing the Meissner effect at superconductor surface
YBCO (thin film)7cm×10cm ×100nm
Magnetic field distribution simulated
散裂中子源进展汇报 January 15, 2019
❖Measured Polarization:P = Cos (B1 ∙ B2)
B1
B2
❖ Adiabatic neutron transition along nutator and
solenoid field
➢ Neutron Polarization direction follows solenoidfield
❖ Non-adiabatic neutron transition across YBCO
film
➢ Neutron Polarization parallel to nutator field are
preserved
Visualizing the Meissner effect at superconductor surface
散裂中子源进展汇报 January 15, 2019
𝑷 = 𝑪𝒐𝒔𝜸𝒎
𝒉𝝀 ∙ 𝑩𝒕𝒓𝒂𝒑 ∙ 𝒍
YBCO (bulk)4cm×4cm ×1cm
Visualizing the Meissner effect at superconductor surface
散裂中子源进展汇报 January 15, 2019
Outlines
▪ 中子散射简介
▪ 中国散裂中子源概况
▪ 极化中子散射
▪ 两个例子▪ 极化中子成像▪ 弱相互作用的测量
散裂中子源进展汇报 January 15, 2019
First Observation of P-odd γ Asymmetry in
Polarized Neutron Capture on Hydrogen
A total of 64 people from 28 institutions worldwide contributed to the study.
散裂中子源进展汇报 January 15, 2019
PV was discovered by C.S. Wu in
1957, by observing a correlation
between the polarization of Co
nuclei and the direction of beta
emission.
Parity Violation
散裂中子源进展汇报 January 15, 2019
Weak
InteractionStrong
Interaction
The Standard Model
Hadronic
Interaction
(residual nuclear
force)
Matter is composed of quarks and leptons, which interact
through the exchange of bosons (force carriers). The
nuclear force (between neutrons and protons) is a residual
effect of both the strong and weak interactions, and can
be interpreted as the exchange of quark-antiquark pairs (,
, -mesons).
散裂中子源进展汇报 January 15, 2019
Measuring difficulties
散裂中子源进展汇报 January 15, 2019
NPDG experiment
散裂中子源进展汇报 January 15, 2019
Hardronic weak interaction theory
For NPDGamma:
散裂中子源进展汇报 January 15, 2019
Spallation Neutron Source at ORNL
•1.4 GeV protons, 60Hz
•Hg Spallation target neutrons
•H2 moderator
•17 m SM guide, curved
10
散裂中子源进展汇报 January 15, 2019
Experimental design
散裂中子源进展汇报 January 15, 2019
Results
We report the most precise and direct determination of h1
π in a few-body system without atomic or nuclear corrections,
and it is the best constraint for future investigation of the HWI.
散裂中子源进展汇报 January 15, 2019
Closing Remarks
中子散射技术作为一种独特的、从原子和分子尺度上研究物质结构和动态特性的表征手段,在多学科交叉领域发挥着不可替代的作用,可以广泛的应用于晶体学、物理、化学、生物、催化、新能源、核工程,、环境,、医药、纳米技术、材料工程、基础物理和信息工程等各科学领域。
散裂中子源进展汇报 January 15, 2019
合作,招聘 -- 建设极化中子中心
正式职工、博后、学生
研究领域:极化3He
极化中子设备极化中子谱仪建设极化中子技术研发控制软件开发
散裂中子源进展汇报 January 15, 2019
Thank you