Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: stana on 25/11/2007 16:04:33
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Hey guys. what was the type of radiation used in the atomic bomb dropped on Hiroshima in 1945?
Gamma
Alpha
or Beta?
thnks!
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To some extent, all 3, as well as neutron radiation. On the other hand, alpha radiation does not penetrate very far, so is generally the safest of the types of radiation, and beta is not far behind.
Gamma radiation can cause serious burns (as can light, and infra-red - they are all at the higher end of the electromagnetic spectrum). These would all have caused short term harm. The neutron radiation can cause longer term harm, as they have the capability of changing atomic nuclei, even turning them into something radioactive.
Aside from that, a lot of radioactive atoms were spewed into the atmosphere over Hiroshima, and these could be breathed in, or ingested, and then trigger a radioactive release within the human body itself (so bypassing any protection that the skin and clothing may have provided to the radiation if it was outside of the body). Many of these elements are also naturally toxic, or become toxic after radioactive decay.
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and then trigger a radioactive release within the human body itself
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What do you mean. Release?
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Radiation can mean many things, and come from many sources, but the kind of radiation we are talking about here is what is nuclear radiation, where an unstable atom decays into a different atom, and emits some radiation in the process.
For instance, one common type of radioactive atom that is created in an atomic bomb is strontium. There are different types of strontium - they all have the same number of protons in the atom (otherwise they would not be strontium atoms), but they have different numbers of neutrons, and these can effect how they decay.
Some forms of strontium (84Sr, 86Sr, 87Sr, and 88Sr) are not radioactive at all, but most other isotopes of strontium are radioactive.
90Sr is for instance radioactive, with a half life of 64 hours (which means that an atom of 90Sr has a 50% chance of decaying into 90Y within 64 hours of its being created). As it happens, strontium is chemically very similar to calcium, so when you ingest strontium, it can easily become incorporated into your bones. If, after having been incorporated into your bones, it then decays to 90Y, then you will have a flash of beta radiation, that could trigger damage to local cells in the vicinity, possibly causing damage to the DNA in the cells, and possibly causing cancer. In small doses, this may be a manageable risk (in fact, this feature of 90Sr is even used to help treat bone cancer - but that assumes that the the risk of the existing bone cancer is greater than the risk of creating new bone cancer).
Polonium is another radioactive element that can be ingested, and this is what is believed to have caused the deliberate poisoning (in this case, 210Po is thought to have been used) of the ex-KGB officer, and dissident, Alexander Litvinenko. It is believed that the polonium came from a nuclear reactor, but it would ofcourse also be created by a nuclear explosion.
http://en.wikipedia.org/wiki/Polonium#210Po
210Po is an alpha emitter that has a half-life of 138.376 days; it decays directly to its daughter isotope 206Pb. A milligram of 210Po emits about as many alpha particles per second as 4.5 grams of 226Ra. A few curies (1 curie equals 37 gigabecquerels) of 210Po emit a blue glow which is caused by excitation of surrounding air.
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What normally happens when you are close to a nuclear explosion is you are either blown to pieces or burnt to death.
As we sank further into the cold war emphasis was on radiation which we might readily shield our selves against so nuclear bombs weren't really that bad