14 DAY TRIAL // A collaboration of Italian astrophysicists recently determined that proposals suggesting a radiation belt should exist around our planet are correct. The hypothesized structure – dubbed the Van Allen radiation belt – was identified using an advanced satellite.
University of Rome investigators led by Piergiorgio Picozza used the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) cosmic-ray instrument on the Resurs-DK spacecraft for this research.
The device is extremely well-suited for conducting this type of researcher, the study team says. As such, scientists decided to use it in order to either confirm or infirm the existence of this proposed radiation belt, Daily Galaxy reports.
According to theory, the Van Allen radiation belt would be comprised primarily of antiprotons, the antimatter equivalents of regular protons. These elementary particles would be produced as a result of interactions between nuclei in Earth's upper atmosphere and cosmic rays.
The latter can be produced by the Sun or other sources, although identifying precisely where the other sources are located has been a long-standing mystery in the field of astrophysics for many years.
As these high-energy particles collide with atoms and particles in our atmosphere, they decay into smaller, less-energetic particles, of which some must be antiprotons. Verifying this has proven difficult because matter-antimatter interactions end with both being annihilated.
Scientists determined that two Van Allen radiation belts exist. The outer one would be made up of lighter particles such as positrons (the antimatter equivalent of electrons), while the inner one would be made up of heavier antiprotons.
While flying through a dense section of the Van Allen belt called the South Atlantic Anomaly – between July 2006 and December 2008 – PAMELA was able to detect no less than 28 antiprotons. This count is about 3 times higher than one would expect to find being produced by solar winds alone.
“The PAMELA collaboration has recently reported the cosmic ray (CR) antiproton spectrum and antiproton-to-proton ratio measurements in the kinetic energy range 60 MeV-180GeV,” the team says.
These data significantly improve those from previous experiments thanks to the high statistical significance and wide energy interval. The results agree with models of purely secondary production where antiprotons are produced through interactions of CRs with the interstellar medium,” they conclude.