Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Nuclear Stability

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...

Nuclear Binding Energy

Nuclear Binding Energy

The difference between the calculated and experimentally measured masses is known as the mass defect of the atom. In the case of helium-4, the mass defect indicates a “loss” in mass of 4.0331 amu – 4.0026 amu = 0.0305 amu. The loss in mass accompanying the formation of an atom from protons, neutrons, and electrons is due to the conversion of that mass into energy that is evolved as the atom forms. The nuclear binding energy is the energy produced when the atoms’ nucleons are bound together;...

Nuclear Fission

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 Fusion

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...

Atomic Nuclei: Nuclear Spin State Overview

Atomic Nuclei: Nuclear Spin State Overview

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 one, the...

Atomic Nuclei: Nuclear Spin State Population Distribution

Atomic Nuclei: Nuclear Spin State Population Distribution

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.

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Crust Composition and the Shallow Heat Source in KS 1731-260.

Physical review letters·2025

Same author

Precision Mass Measurements Reveal Low Neutron Pairing in Tin beyond N=82 and Its Impact on Stellar Nucleosynthesis.

Physical review letters·2025

Same author

Do cell culturing influence the radiosensitizing effect of gold nanoparticles: a Monte Carlo study.

EJNMMI physics·2025

Same author

Bound-State Beta Decay of ^{205}Tl^{81+} Ions and the LOREX Project.

Physical review letters·2024

Same author

Novel Bragg peak characterization method using proton flux measurements on plastic scintillators.

Physics in medicine and biology·2024

Same author

Excited-State Half-Lives in ^{130}Cd and the Isospin Dependence of Effective Charges.

Physical review letters·2024

Search research articles

Related Experiment Video

Updated: Jul 20, 2026

Laser-heating and Radiance Spectrometry for the Study of Nuclear Materials in Conditions Simulating a Nuclear Power Plant Accident

Laser-heating and Radiance Spectrometry for the Study of Nuclear Materials in Conditions Simulating a Nuclear Power Plant Accident

Published on: December 14, 2017

Electron capture rates on nuclei and implications for stellar core collapse.

K Langanke¹, G Martínez-Pinedo, J M Sampaio

¹Institute for Physics and Astronomy, University of Arhus, DK-8000 Arhus C, Denmark.

Physical Review Letters

|July 15, 2003

Summary

Electron capture on nuclei, not free protons, dominates during core collapse supernovae. This finding significantly alters supernova simulations and our understanding of stellar evolution.

More Related Videos

Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers

Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers

Published on: August 18, 2017

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Published on: June 7, 2018

Related Experiment Videos

Last Updated: Jul 20, 2026

Laser-heating and Radiance Spectrometry for the Study of Nuclear Materials in Conditions Simulating a Nuclear Power Plant Accident

Laser-heating and Radiance Spectrometry for the Study of Nuclear Materials in Conditions Simulating a Nuclear Power Plant Accident

Published on: December 14, 2017

Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers

Coulomb Explosion Imaging as a Tool to Distinguish Between Stereoisomers

Published on: August 18, 2017

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Published on: June 7, 2018

Area of Science:

Nuclear astrophysics
Computational astrophysics
Stellar evolution

Background:

Supernova simulations traditionally assume electron capture on free protons dominates during core collapse.
Electron capture on heavy nuclei is often neglected due to assumed Pauli blocking.

Purpose of the Study:

To calculate electron capture rates on nuclei with mass numbers A=65-112 under core collapse conditions.
To reassess the dominant electron capture mechanism in core collapse supernovae.

Main Methods:

Calculation of electron capture rates on specific nuclei (A=65-112).
Inclusion of relevant temperatures and densities characteristic of core collapse.

Main Results:

Electron capture rates on nuclei are found to be significantly large.
Electron capture on nuclei dominates over capture on free protons, contrary to prior assumptions.

Conclusions:

The dominance of electron capture on nuclei necessitates revisions to current supernova core collapse simulations.
This revised understanding impacts models of stellar explosions and nucleosynthesis.