揭示了镜核H和He的短程结构
S Li1,2, R Cruz-Torres2,3, N Santiesteban1,3
1Department of Physics and Astronomy, University of New Hampshire, Durham, NH, USA.
Nature
|August 31, 2022
概括
通常由中子-质子对主导的原子核中的短距离相关性 (SRC) 在-3和-3中显示出令人惊的偏差. 这一发现提供了对短距离核子相互作用的新见解.
科学领域:
- 核物理
- 量子染色学
- 核天体物理学
背景情况:
- 原子核由通过强核力相互作用的质子和中子 (核子) 组成.
- 短距离相关性 (SRC) 是核中的高能量核子对,对于理解核结构至关重要.
- SRC (中子-质子对质子对) 的同旋结构对于核和天体物理模型至关重要.
研究的目的:
- 在三核系统 (-3和-3) 中精确测量中子-质子 (np) 与质子-质子 (pp) 的比例.
- 研究轻核中SRC的同回旋结构,并将其与较重核中的观测进行比较.
- 通过了解不同核环境中的SRC行为来完善核子-核子相互作用的模型.
主要方法:
- 使用了镜子核,3和3的散射实验.
- 分析散射数据以提取短距离相关性的np/pp比率.
- 采用先进的核物理技术来最大限度地减少依赖模型的纠正.
主要成果:
- 与之前的实验相比,NP/pp SRC比率的测量精度得到了数量级的提高.
- 从通常在重核中观察到的SRC的近总np主导度中观察到显著的偏差.
- 在3和3的高动量波函数中发现了一个意想不到的结构.
结论:
- 在轻型三核系统中,SRC的同回旋结构与较重核的同回旋结构明显不同.
- 这些发现挑战了目前对短距离核子相互作用和核波函数的理解.
- 需要进一步的理论和实验工作才能充分理解对核物理和天体物理学的影响.
更多相关视频
14:55Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
15.5K
10:10Neutron Crystallography Data Collection and Processing for Modelling Hydrogen Atoms in Protein Structures
Published on: December 1, 2020
5.1K
相关概念视频
Atomic Nuclei: Nuclear Spin State Population Distribution
1.1K
Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.
1.1K
Nuclear Stability
19.4K
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together...
To hold positively charged protons together...
19.4K
Atomic Nuclei: Nuclear Magnetic Moment
1.4K
All atomic nuclei are positively charged. When they have a nonzero spin, they behave like rotating charges. As a consequence of their charge and spin, these nuclei generate a magnetic field (B). This, in turn, gives rise to a magnetic moment (μ), which is randomly oriented in the absence of an external magnetic field. When an external magnetic field (B0) is applied, the magnetic moment vectors can align with the field or against it in 2 + 1 orientations. A hydrogen nucleus, which is just a...
1.4K
Atomic Nuclei: Nuclear Spin
2.4K
All atomic particles possess an intrinsic angular momentum, or 'spin'. Electrons, protons, and neutrons each have a spin value of ½, although protons and neutrons in nuclei may have higher half-integer spins owing to energetic factors.
Atomic nuclei have a net nuclear spin, , which can have an integer or half-integer value. In atomic nuclei, the spins of protons are paired against each other but not with neutrons, and vice versa. Consequently, an even number of protons does not...
Atomic nuclei have a net nuclear spin, , which can have an integer or half-integer value. In atomic nuclei, the spins of protons are paired against each other but not with neutrons, and vice versa. Consequently, an even number of protons does not...
2.4K
Atomic Nuclei: Nuclear Spin State Overview
1.1K
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of...
1.1K
Other Nuclides: 31P, 19F, 15N NMR
449
Many organic, inorganic, and biological molecules contain spin-half nuclei such as nitrogen-15, fluorine-19, and phosphorus-31. As a result, NMR studies of these nuclei have found extensive applications in chemical and biological research.
While fluorine-19 and phosphorous-31 have high natural abundances (100%) and positive gyromagnetic ratios, nitrogen-15 has a low natural abundance and a negative gyromagnetic ratio. However, nitrogen-15 is still preferred over nitrogen-14 (which has a...
While fluorine-19 and phosphorous-31 have high natural abundances (100%) and positive gyromagnetic ratios, nitrogen-15 has a low natural abundance and a negative gyromagnetic ratio. However, nitrogen-15 is still preferred over nitrogen-14 (which has a...
449
