関連する実験動画
Updated: Aug 17, 2026

14:22
Activating Molecules, Ions, and Solid Particles with Acoustic Cavitation
Published on: April 11, 2014
地球のマントルで発見されたプルトニウム分裂クセノン
1J. Kunz, Institut de Physique du Globe de Paris, Laboratoire de Geochimie et Cosmochimie, Centre National de la Recherche Scientifique URA 1758, 4 place Jussieu, F-75252 Paris Cedex 05, France. T. Staudacher, Institut de Physique du.
まとめ
プルトニウム244の分裂は,地球の30%を説明しています.
科学分野:
- 地質化学 地質化学
- 宇宙化学 (コスモケミストリー)
- 惑星科学 惑星科学
背景:
- 地球の内部にあるキセノン同位体は,初期の太陽系プロセスについての洞察を提供します.
- 放射性高貴ガスは,惑星の形成と進化の重要なトレーサーである.
研究 の 目的:
- プルトニウム-244の核分裂が地球上の核分裂性クセノンに与える貢献を定量化するために.
- 地球の蓄積と大気形成のタイミングを精査する.
主な方法:
- 中洋のの玄武岩ガラスの分析.
- 放射線年代測定法 放射線年代測定法
- クセノンおよびその他の貴気ガスの同位体分析.
主要な成果:
- プルトニウム244 (Pu-244) の分裂は,分裂性クセノン過剰の約30%を占めています.
- ウラン238 (U-238) の自発的な分裂は,残りの分裂性クセノンを説明する.
- クセノン-129 (Xe-129) の過剰は,太陽系形成の5千万~7千万年後の地球の蓄積が終わったことを示している.
結論:
- Pu-244のような初期の太陽系放射性核は,地球の同位体組成に大きな影響を与えた.
- 地球の大気は,マントルの脱ガス化によって形成された可能性が高い.
- 地球の蓄積のタイミングは,絶滅した放射性核酸のデータによって制限されています.
関連する概念動画
Noble Gases
The elements in group 18 are noble gases (helium, neon, argon, krypton, xenon, and radon). They earned the name “noble” because they were assumed to be nonreactive since they have filled valence shells. In 1962, Dr. Neil Bartlett at the University of British Columbia proved this assumption to be false.
Nuclear Stability
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 in the...
To hold positively charged protons together in the...
Nuclear Fission
Many heavier elements with smaller binding energies per nucleon can decompose into more stable elements that have intermediate mass numbers and larger binding energies per nucleon—that is, mass numbers and binding energies per nucleon that are closer to the “peak” of the binding energy graph near 56. Sometimes neutrons are also produced. This decomposition of a large nucleus into smaller pieces is called fission. The breaking is rather random with the formation of a large number of different...
Nuclear Power
Controlled nuclear fission reactions are used to generate electricity. Any nuclear reactor that produces power via the fission of uranium or plutonium by bombardment with neutrons has six components: nuclear fuel consisting of fissionable material, a nuclear moderator, a neutron source, control rods, reactor coolant, and a shield and containment system.
Nuclear Fuels
Nuclear fuel consists of a fissile isotope, such as uranium-235, which must be present in sufficient quantity to provide a...
Nuclear Fuels
Nuclear fuel consists of a fissile isotope, such as uranium-235, which must be present in sufficient quantity to provide a...
Nuclear Fusion
The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process called fusion. The principal source of energy in the sun is a net fusion reaction in which four hydrogen nuclei fuse and ultimately produce one helium nucleus and two positrons.
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...
Nuclear Transmutation
Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest Rutherford’s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with other nuclei or with neutrons. Rutherford bombarded nitrogen-14 atoms with high-speed α particles from a natural radioactive isotope of radium and observed protons being...

