電子-陽子散射実験から得られた小さな陽子電荷半径
W Xiong1, A Gasparian2, H Gao1
1Duke University and Triangle Universities Nuclear Laboratory, Durham, NC, USA.
Nature
|November 8, 2019
まとめ
陽子半径のパズルは残っていますが,この研究は
科学分野:
- 原子,分子,光学物理学
- 核物理学
- 量子電動学
背景:
- 陽子の電荷半径 (rp) は,電子-陽子の散乱と水素スペクトロスコーピーによって伝統的に決定される.
- 陽子半径パズルとして知られるこの不一致は 2010年にミオニック水素実験の結果から明らかになった.
- 最近のスペクトル測定では 普通の水素も不一致で 未解決の問題を示しています
研究 の 目的:
- 陽子の電荷半径を正確に測定する 新しい電子-陽子散射法を使って
- 新しい実験データを提供することで,進行中の"陽子半径パズル"を解決する.
- rp の実験値と理論値の違いを調査する.
主な方法:
- ジェファーソン研究所 (PRad) で高精度の電子-陽子散射実験を行った.
- 前回の実験の限界を克服するために,磁気スペクトロメーターフリーメソッドを使用しました.
- 非常に小さな前方分散角度での測定のための窓のない水素ガスのターゲットを実装した.
主要な成果:
- 陽子の電荷半径を rp = 0.831 ± 0.007stat ± 0.012systフェムトメーターで測定した.
- この結果は,最新の高精度電子-陽子散乱測定よりも小さい.
- 測定された値は,以前のすべての電子-陽子散射結果の平均より2. 7の標準偏差です.
結論:
- 新しい測定は,ミオニック水素実験から得られたより小さな陽子電荷半径値をサポートします.
- 物理学における基本的な定数である リッドバーグ定数と一致しています
- この研究は,長年にわたる"陽子半径パズル"の解明に貢献しています.
さらに関連する動画
関連する概念動画
Subatomic Particles
111.0K
Dalton was only partially correct about the particles that make up matter. All matter is composed of atoms, and atoms are composed of three smaller subatomic particles: protons, neutrons, and electrons. These three particles account for the mass and the charge of an atom.
111.0K
Electron Behavior
11.2K
Electrons are negatively charged subatomic particles attracted to and orbit around the positively-charged nucleus of an atom. They reside in spaces associated with energy levels called shells and are further organized into subshells and orbitals within each shell.
Electrons Orbit the Nucleus
Electrons are found in specific locations outside of the nucleus. The shell in which an electron resides indicates the general energy level of the electron: those closer to the nucleus have less energy,...
Electrons Orbit the Nucleus
Electrons are found in specific locations outside of the nucleus. The shell in which an electron resides indicates the general energy level of the electron: those closer to the nucleus have less energy,...
11.2K
Electron Behavior
106.9K
Overview
Electrons are negatively charged subatomic particles that are attracted to an orbit around the positively-charged nucleus of an atom. They reside in locations that are associated with energy levels called shells and are further organized into sub-shells and orbitals within each shell.
Electrons Orbit the Nucleus
Electrons are found in specific locations outside of the nucleus. The shell in which an electron resides indicates the general energy level of the electron: those closer to the...
Electrons are negatively charged subatomic particles that are attracted to an orbit around the positively-charged nucleus of an atom. They reside in locations that are associated with energy levels called shells and are further organized into sub-shells and orbitals within each shell.
Electrons Orbit the Nucleus
Electrons are found in specific locations outside of the nucleus. The shell in which an electron resides indicates the general energy level of the electron: those closer to the...
106.9K
Atomic Radii and Effective Nuclear Charge
61.3K
The elements in groups of the periodic table exhibit similar chemical behavior. This similarity occurs because the members of a group have the same number and distribution of electrons in their valence shells.
61.3K
Thomson's e/m Experiment
6.3K
In a beam of charged particles created by a heated cathode, the particles move at different speeds. However, many applications need a beam with uniform particle speeds. An arrangement known as a velocity selector uses electric and magnetic fields to pick particles with a particular speed from the beam.
A particle with charge q, speed v, and mass m enters an area from the top, where the magnetic and electric fields are perpendicular both to the particle's motion and to one another. The magnetic...
A particle with charge q, speed v, and mass m enters an area from the top, where the magnetic and electric fields are perpendicular both to the particle's motion and to one another. The magnetic...
6.3K
Ionic Radii
33.0K
Ionic radius is the measure used to describe the size of an ion. A cation always has fewer electrons and the same number of protons as the parent atom; it is smaller than the atom from which it is derived. For example, the covalent radius of an aluminum atom (1s22s22p63s23p1) is 118 pm, whereas the ionic radius of an Al3+ (1s22s22p6) is 68 pm. As electrons are removed from the outer valence shell, the remaining core electrons occupying smaller shells experience a greater effective nuclear...
33.0K


