電子の形状の測定が改善されました
J J Hudson1, D M Kara, I J Smallman
1Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, UK.
Nature
|May 27, 2011
まとめ
科学者たちは,電子電極二極モメント (EDM) を探し,標準モデルを超えた新しい物理学の兆候である. 実験では,電子のEDMの証拠は見つかりませんでしたが,電子は前例のない精度で球状であることを示しています.
科学分野:
- * 素粒子物理学について
- * 量子力学 量子力学とは
- * 天体物理学
背景:
- * 電子の電極二極モメント (EDM) は,球体対称性からの偏差の尺度です.
- * 粒子物理学の標準モデルは,現在の実験的検出限界をはるかに下回る,非常に小さな電子EDMを予測しています.
- * 標準模型の拡張と,宇宙の物質対抗物質の非対称性に関する理論は,より大きく,潜在的に検出可能な電子電子電子メカニズム (EDM) を予測する.
研究 の 目的:
- * 電子電極二極モメント (EDM) を今までの最高精度で探す.
- * 標準モデルを超えた新しい物理学,特に超対称性を制限する.
- * EDMと宇宙における物質対抗物質の非対称性との関係を調査する.
主な方法:
- *高精度測定を行うために冷たい極性分子を利用しました.
- *測定されたアットー電子ボルトのエネルギーシフトは,分子内のものです.
- * 最先端の実験技術を用いて,前例のない感度を達成した.
主要な成果:
- * 電子EDMの測定値を取得しました:d(e) = (-2.4 ± 5.7(stat) ± 1.5(syst)) × 10−28 e·cm.
- * 電子EDMの新しい上限を確立しました: ≪d (e) ≪ 10.5 × 10−28 e・cm 90%の信頼性で.
- *結果はゼロと一致し,この精度レベルでは電子が球形であることを示します.
結論:
- *検出可能な電子EDMの欠如は,超対称性を含む標準モデルを超えた理論に厳格な制約を課します.
- * この測定はテラ電子ボルトのエネルギースケールで新しい物理学の探査を行っています.
- *この正確な測定は,基本的な粒子特性や,物質と反物質の不均衡のような宇宙学的パズルの理解に貢献します.
関連する概念動画
The Uncertainty Principle
Werner Heisenberg considered the limits of how accurately one can measure properties of an electron or other microscopic particles. He determined that there is a fundamental limit to how accurately one can measure both a particle’s position and its momentum simultaneously. The more accurate the measurement of the momentum of a particle is known, the less accurate the position at that time is known and vice versa. This is what is now called the Heisenberg uncertainty principle. He mathematically...
NMR Spectrometers: Resolution and Error Correction
When magnetic nuclei in a sample achieve resonance and undergo relaxation, the signal detected in NMR is an approximately exponential free induction decay. Fourier transform of an exponential decay yields a Lorentzian peak in the frequency domain. Lorentzian peaks in an NMR spectrum are defined by their amplitude, full width at half maximum, and position, where the peak width is governed by the spin-spin relaxation time alone. In real experiments, however, the applied magnetic field is rendered...
Overview of Electron Microscopy
The wavelengths of visible light ultimately limit the maximum theoretical resolution of images created by light microscopes. Most light microscopes can only magnify 1000X, and a few can magnify up to 1500X. Electrons, like electromagnetic radiation, can behave like waves, but with wavelengths of 0.005 nm, they produce significantly greater resolution up to 0.05 nm as compared to 500 nm for visible light. An electron microscope (EM) can create a sharp image that is magnified up to 2,000,000X.
Scanning Electron Microscopy
A scanning electron microscope (SEM) is used to study the surface features of a sample by using an electron beam that scans the sample surface in a two-dimensional manner. Typically, areas between ~1 centimeter to 5 micrometers in width can be imaged. SEM can be used to image bacteria, viruses, tissues as well as larger samples like insects. Conventional SEM gives a magnification ranging from 20X to 30,000X and spatial resolution of 50 to 100 nanometers.
Fundamental Principles
Accelerated...
Fundamental Principles
Accelerated...
Transmission Electron Microscopy
In 1931, physicist Ernst Ruska—building on the idea that magnetic fields can direct an electron beam just as lenses can direct a beam of light in an optical microscope—developed the first prototype of the electron microscope. This development led to the development of the field of electron microscopy. In the transmission electron microscope (TEM), electrons are produced by a hot tungsten element and accelerated by a potential difference in an electron gun, which gives them up to 400 keV in...
Electron Microscope Tomography and Single-particle Reconstruction
Transmission electron microscopy (TEM) can be used to determine the 3D structure of biological samples with the help of techniques such as electron microscope tomography and single-particle reconstruction. While single-particle reconstruction can examine macromolecules and macromolecular complexes in vitro conditions only, tomography permits the study of cell components or small cells in vivo.
Electron Tomography
Electron tomography can be performed either in TEM or STEM (scanning transmission...
Electron Tomography
Electron tomography can be performed either in TEM or STEM (scanning transmission...


