Related Experiment Video
Updated: Jun 21, 2026
08:48
High-Resolution Neutron Spectroscopy to Study Picosecond-Nanosecond Dynamics of Proteins and Hydration Water
Published on: April 28, 2022
Positron kinetics in soft condensed matter
1ARC Centre for Antimatter-Matter Studies, James Cook University, Townsville 4810, Australia. Ronald.White@jcu.edu.au
Physical Review Letters
|August 8, 2009
Summary
A new kinetic theory models positron behavior in soft matter by combining molecular scattering data with medium structure. This theory explains negative differential conductivity in liquid argon due to positron formation and medium properties.
Area of Science:
- Condensed matter physics
- Plasma physics
- Computational physics
Background:
- Understanding charged particle behavior in condensed matter is crucial for various applications.
- Existing theories often simplify the complex interactions within soft matter.
- Positron interactions are particularly complex due to their antimatter nature.
Purpose of the Study:
- To develop a novel kinetic theory for positrons in soft matter.
- To incorporate both single-molecule scattering and medium structure effects.
- To investigate phenomena like negative differential conductivity.
Main Methods:
- Developed a kinetic theory integrating positron-molecule cross-sections with the medium's structure function.
- Applied the theory to positrons in liquid argon.
- Performed numerical simulations to analyze positron behavior.
Main Results:
- The new theory successfully models positron dynamics in soft matter.
- Numerical results for liquid argon show negative differential conductivity.
- This conductivity is attributed to positron formation and the medium's structure.
Conclusions:
- The developed kinetic theory provides a more comprehensive understanding of positrons in soft matter.
- The findings highlight the importance of medium structure in positron transport.
- The study offers insights into the mechanisms behind negative differential conductivity.
Related Concept Videos
01:09Electron Behavior
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,...
00:54Electron Behavior
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 NucleusElectrons 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...
01:14Atomic 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.
01:27π Electron Effects on Chemical Shift: Overview
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0, resulting in...
02:45The Quantum-Mechanical Model of an Atom
Shortly after de Broglie published his ideas that the electron in a hydrogen atom could be better thought of as being a circular standing wave instead of a particle moving in quantized circular orbits, Erwin Schrödinger extended de Broglie’s work by deriving what is now known as the Schrödinger equation. When Schrödinger applied his equation to hydrogen-like atoms, he was able to reproduce Bohr’s expression for the energy and, thus, the Rydberg formula governing hydrogen spectra. Schrödinger...
01:23Equilibrium Conditions for a Particle
When an object is in equilibrium, it is either at rest or moving with a constant velocity. There are two types of equilibrium: static and dynamic. Static equilibrium occurs when an object is at rest, while dynamic equilibrium occurs when an object is moving with a constant velocity. In both cases, there must be a balance of forces acting on the object.
To understand the concept of equilibrium, let us first consider the forces acting on an object. When different forces act on an object, they can...
To understand the concept of equilibrium, let us first consider the forces acting on an object. When different forces act on an object, they can...