Step outside on a nice day and feel the sun’s warmth – that’s radiation; so’s the light. A body’s warmth is radiation. And radio waves. And television signals. And x-rays. And light from a glow worm’s tail.
Radiation is energy transfer. It can take several forms. One is tiny mass-less packets called photons. We experience photons most commonly as ordinary light. This radiation frequently is called electromagnetic radiation. Photons carry energy, and the more energetic they are, the higher their frequency, the more “dangerous” they can be. Harm results when energy is transferred to living cells in a damaging way. Early atomic scientists identified a form of radiation they called “gamma rays.” Ironically, it turned out to be nothing more than high energy photons, but the name still is frequently used.
Electrons can carry energy as radiation, too. Since electrons have mass, in the strictest sense they should not be called radiation, but no one ever claimed English was precise. Because of their mass, if electrons are moving fast enough when they strike something, they cause damagelike a bullet. Early atomic scientists named this radiation “beta rays” before they determined that it was only electrons. The name stuck.
Neutrons carry energy as radiation much like electrons, except that neutrons are much heavier, and so can cause more damage for a given speed. Since they have no electric charge, they cannot be deflected by a magnetic field like electrons.
Several subatomic particles actually emit gamma rayshigh energy photonsand are sufficiently light that they travel some distance, appearing, therefore, as radiation themselves. An especially common one is a helium atom without any electrons. Early atomic scientists called this an “alpha particle” before realizing what it actually wasthey still use the name.
There is a host of other radiation typesbecause there is a host of particles with and without mass that can carry energy away from an atom. From an every day perspective, however, they are relatively unimportant.
We deal with “radiation” every single moment of our lives. It is utterly, absolutely vital to our existence. When radiation is very energetic, how-ever, we must be careful. Sunburn is caused by high-energy light (ultra-violet radiation). A hot stove (infra-red radiation) can cook. X-rays (high energy photons) can disrupt cell functions, as can high energy electrons and neutrons. Alpha particles are not intrinsically dangerous since the photons they give off are relatively low energy. If ingested, however, so they come into intimate contact with vital organs, then the released energy can damage. [Nuclear fall-out (dust) is primarily in this category.]
One especially useful and exciting application for radiation is sterilizing food. A properly designed machine can set the energy level and focus both photon and electron radiation so that it kills bacteria while leaving other cells untouched. Food treated in this manner can last indefinitely while retaining its fresh taste and character. Since the “radiation” used is not in the category of “alpha particles,” it is entirely impossible for the food to become contaminated by the “radiation.” This makes irradiation the safest possible method for sterilizing food. Any other method either does not work as wellleaves bacteria behindor presents the likelihood of contaminating the food with the sterilizing chemical.
Food irradiation will greatly enhance humankind’s ability to feed itself. It is one of the most significant, exciting developments to come from nuclear research!
