The most common health hazard associated with radiation is cancer. The news has made the public very aware of this fact. The devastating effects of extremely large dosages of radiation is indeed harmful. Pictures form the aftermath of Hiroshima and Chernobyl attest to this. The dangers associated with much lower levels of radiation are not so clear.
As cloud chambers show, radiation is always around us.. It is possible to see examples of the natural background radiation by looking at a cloud chamber with no radioactive source in it. Sensitive chambers show a continual barrage of particles. A person is struck by a radioactive particle, once a second for each square centimeter on their body. Cloud chambers make it extremely easy to visualize the radioactive tracks that are continually around us. It is impossible to escape the effects of radiation. The very potassium in our body is a significant source of radiation. It is, however, possible to minimize our exposure to radioactive particles. As one can see from figures representing the sources of our radiation exposure, the largest sources are relatively impossible to control. Natural deposits in the soil contribute a large fraction of our annual radiation dose. Secondary cosmic radiation produced in the atmosphere from high energy stellar cosmic particles also continually douse us with radiation. It is really only the very minor sources that we can control. These minor sources are usually the ones being publicly touted as lethal. However few stop to realize that radiation from radon gas in one's basement is a higher source of radiation than that received by a nuclear power plant next door.
Large sources of extra radiation can come from unexpected sources. Pilots and Stewardess receive at least equal radiation dosages as any worker in a nuclear power plant. The higher in elevation one is, the less atmosphere one has to be shielded from radioactive cosmic rays. This has become quite a serious issue for members of the airline industry. The most sane way to understand radiation is to be able to put it into perspective. Radiation is not merely a byproduct of modern technology. Cloud chambers would have shown the same background radiation levels 100 years ago as they would today.
More Sophisticated Detectors
Cloud chambers made it possible to study the unseen world of atomic physics. Today many physicists are interested in finding out more about the inner structure of atom. Newer and more sensitive devices are used. As seen below, large bubble chambers can show unusual reactions such as a p+ meson reacting with a Helium nucleus, to split the nucleus and produce a He1, a He3 and a p+ and p- meson
To simulate or induce very rare reactions, high energy particle accelerators have been developed. Accelerators such as TRIUMFat UBC, or fermi-lab below are very large in order to confine the high energies required.
The information that instruments such as these have provided us, have proven to be invaluable in our understanding the atomic universe.
Other Links on Radiation and Cloud Chambers
Supersaturated Enviroonments : a company that sells large cloud chambers.
radiation.: a good link with lots of general information on
FAQ: a general frequently asked question page on radiation
Radiation is most often connected with increased rates of cancer. Cancer occurs when cells mutate and start to reproduce uncontrollably. This occurs when a cells genetic code is modified. This usually happens by rare errors in DNA replication. Radiation, can also cause this. Radioactive particle are able to ionize the bonds that form DNA. This may lead to the miscoding of information. The body has many natural defenses against this. As mentioned before, alpha particle will react with our dead skin before reaching any vital organs. Gamma particles usually pass completely through our body. If any source of radiation is to have a harmful effect it must also have significant enough energy to ionize one of the DNA bonds. The DNA size also minimizes radiation caused cancer. The DNA is usually very compact. Radioactive particle must be able to pass near enough the tiny DNA in order to react with it. In addition, the body can also repair mistakes along the DNA double helix. If a cell does happen to mutate, mutation usually results in the cell's death. If not, the body has a strong immune system of white blood cells to destroy any surviving mutants. If all of this fails, a cell may become cancerous. This is a natural occurrence. Radiation only serves to somewhat increase the chances that a cell may mutate. For those who fear any exposure to anything radioactive, they might find it ironic that evolutionary changes caused by cell mutation, which radiation can slightly increase, have caused us to come into being.
While radiation increases the chance of developing cancer, it is often used to combat it as well. Kemotherapy uses radiation to accurately destroy a region of mutating cells. Radiation is also used for some types of medical imaging, such as PET scans. Recent outbreaks of E.Coli bacteria, and the associated deaths, have led to increase pressure to irradiate meats and other food. Food is exposed to gamma rays. These radioactive particles destroy bacteria such as E.coli. Thus they serve as very good preservatives. Food does not become radioactive, because no neutrons are absorbed to destabilize the nucleus of the irradiated food. High energy neutrons are also being used as bomb detectors in airplanes. Since x-rays only show the shape of an object, not its composition, airplanes are very subject to basically simple explosives. Neutrons sent through luggage, can easily discern phosphate loaded bomb material. Radioactive decay is also responsible for the invaluable technique of carbon dating. Since radioactivity levels decrease with time, it is relatively simple to calculate how old something is by its relative radioactivity.