EPJ D Highlight - Colliding molecules and antiparticles
- Details
- Published on 13 December 2019

A new theoretical study of the interaction between positrons and simple tetrahedral and octahedral molecules agrees with experimental work and could have useful implications for PET scanning techniques.
Antiparticles - subatomic particles that have exactly opposite properties to those that make up everyday matter - may seem like a concept out of science fiction, but they are real, and the study of matter-antimatter interactions has important medical and technological applications. Marcos Barp and Felipe Arretche from the Universidade Federal de Santa Catarina, Brazil have modelled the interaction between simple molecules and antiparticles known as positrons and found that this model agreed well with experimental observations. This study has been published in EPJ D.
Positrons, the antimatter equivalent of electrons, are the simplest and most abundant antiparticles, and they have been known and studied since the 1930s. Particle accelerators generate huge quantities of high-energy positrons, and most lab experiments require this energy to be reduced to a specific value. Typically, this is achieved by passing the positrons through a gas in an apparatus called a buffer-gas positron trap, so they lose energy by colliding with the molecules of the gas. However, we do not yet fully understand the mechanisms of energy loss at the atomic level, so it is difficult to predict the resulting energy loss precisely.
Some of this energy is lost as rotational energy, when the positrons collide with gas molecules and cause them to spin. Barp and Arretche developed a model to predict this form of energy loss when positrons collide with molecules often used in buffer-gas positron traps: the tetrahedral carbon tetrafluoride (CF4) and methane (CH4), and the octahedral sulphur hexafluoride (SF6). They found that this model compared very well to experimental results.
This model can be applied to collisions between positrons and any tetrahedral or octahedral molecules. Barp and Arretche hope that this improved understanding of how positrons interact with molecules will be used to improve techniques for positron emission tomography (PET) scanning in medicine, for example.
M.V. Barp and F. Arretche (2019) Rotational excitation of tetrahedral and octahedral molecules caused by electron and positron impact, European Physical Journal D 73: 244, DOI: 10.1140/epjd/e2019-100444-5
Open calls for papers
-
EPJ A Topical Issue: First joint gravitational wave and electromagnetic observations: Implications for nuclear and particle physics
-
EPJ A Topical Issue: Heavy and Super-Heavy Nuclei and Elements: Production and Properties
-
EPJ A Topical Issue: Light clusters in nuclei and nuclear matter: Nuclear structure and decay, heavy ion collisions, and astrophysics
-
EPJ A Topical Issue: The QCD Phase Diagram in Strong Magnetic Fields
-
EPJ B Topical Issue: Extreme Value Statistics and Search in Biology: Theory and Simulations
-
EPJ B Topical Issue: Evolutionary Game Theory
-
EPJ B Topical Issue: Recent progress and emerging trends in Molecular Dynamics
-
EPJ D Topical Issue: Atoms and Molecules in a Confined Environment
-
EPJ D Topical Issue: Low Temperature Plasmas: Processes, Diagnostics and Applications
-
EPJ D Topical Issue: Quantum Aspects of Attoscience
-
EPJ D Topical Issue: Spectroscopy of biomolecular ions in vacuo
-
EPJ D Topical Issue: “Advances in Physics of Ionized Gases and Spectroscopy of Isolated Complex Systems: from Biomolecules to Space Particles" (2020)
-
EPJ E Special Issue: Diffusion and Convection in Nature
-
EPJ E Topical Issue: Physics and Geometry of Flexible Plates and Shells
-
EPJ E Topical Issue: Advances in Computational Methods for Biological Physics
-
EPJ E Topical Issue: Disordered, non-equilibrium systems: From supercooled liquids to amorphous solids
-
EPJ E Topical Issue: Physics of phase separation in cell biophysics: From non-equilibrium droplets to reaction-diffusion systems
-
EPJ E Topical Issue: Tissue Mechanics
-
EPJ N Topical Issue: Liquid-gas and liquid-vapour flows: theory, simulation and experiments
-
EPJ Plus Focus Point Issue: Breakthrough optics- and complex systems-based technologies of modulation of drainage and clearing functions of the brain
-
EPJ Quantum Technology: Special Issue on Quantum Industry
-
EPJ Quantum Technology: Special Issue on Quantum Metrology & Quantum Enhanced Measurement
-
EPJ ST Special Issue: Transport properties of non-Newtonian nanofluids and applications
-
EPJ ST Special Issue: Chaotic variable-order fractional neural networks
-
EPJ ST Special Issue: Circuit Application of Chaotic Systems: Modeling, Dynamical Analysis and Control
-
EPJ ST Special Issue: Complex Bio Rhythms
-
EPJ ST Special Issue: Intense laser-matter interaction in atoms, finite and condensed systems
-
EPJ ST Special Issue: Modeling, Machine Learning and Astronomy
-
EPJ ST Special Issue: Non-equilibrium phase transitions in heterogeneous systems: biophysical aspects
-
EPJ ST Special Issue: Strong Correlations in Dense Matter Physics
-
EPJ ST Special Issue: The Accelerating Universe – Evidence and Theories
-
EPJ ST Special Issue: Tipping in Complex Systems: Theory, Methods & Applications
-
EPJ Techniques and Instrumentation: Instrumentation and Control of Large Helium Cryogenic Systems
-
EPJ Techniques and Instumentation: Diagnostics for electric propulsion systems