Beta Particle
Written by John Carl Villanueva
The Large Area Telescope (LAT) on Fermi detects gamma-rays through matter (electrons) and antimatter (positrons) they produce after striking layers of tungsten. Credit: NASA/Goddard Space Flight Center Conceptual Image Lab
This ionization property refers to a particle's ability to impart a charge to an originally neutral particle. For example, when a beta particle collides with an atom, it can remove an electron thereby rendering a positive charge to the atom. If the atom resides in a cell, the cell can then be damaged. This is precisely the reason why beta particles, just like all types of ionizing radiation, are harmful to the body.
Just to remind you of your high school physics, there are three types of ionizing radiation: alpha, beta, and gamma. Alpha particles are the heaviest and slowest, while gamma particles are the lightest and fastest. Beta particles, as you may have guessed by now, are somewhere in between.
These energetic electrons and positrons can be stopped by a few mm of aluminum. That would make them more penetrating than alphas but less than gammas. If you want to compare the three, alpha particles can be stopped by a sheet of paper, while gamma particles require thick layers of lead.
To give you an idea how lightweight these particles are compared to their heavyweight cousins, the alpha particles, a beta particle is just 1/2000 of the mass of a single proton or neutron. That alone shows the extreme disparity in terms of mass. Still, it is their very fast velocities, and subsequently very large momenta, that give them the ability to ionize.
There are two main conditions that spur the release of beta particles from radioactive nuclei: (1) when there is just too many neutrons compared to protons and (2) when there is just too many protons compared to neutrons. Easy to recall, isn't it?
In the case of the first condition, electrons will be released accompanied by the conversion of a neutron to a proton. Accordingly, the term beta minus decay denotes such a process. For the second condition, on the other hand, positrons will be released accompanied by a conversion of a proton to a neutron, and in the same manner, the term beta plus decay is used.
Some of the well-known beta-emitters, i.e., nuclei that are known to emit beta particles, are tritium, cobalt-60, strontium-90, technetium-99, iodine-129, and cesium-137.
Like that article? Allow us to recommend a few more that can be found hire at University Today. Want to know about howFermilab is putting the squeeze on the Higgs boson? There's also some related info among the comments on this article: What Was Before the Big Bang? An Identical, Reversed Universe. FYI, there are actually a lot of informative text from our readers on this site.
There's more still at SLAC. Here are a couple of sources there:
Here are two episodes at Astronomy Cast that you might want to check out as well:
- Avoiding the Heat Death, Orbiting Galaxies, and the Dangers of Space Radiation
- Hidden Fusion, the Speed of Neutrinos, and Hawking Radiation
Filed under: Astronomy
Tags: beta particle, electron, positron, radiation
