 | Term | Definition |
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radioactive nuclei |
nuclei that undergo spontaneous changes and emit energy in the form of radiation |
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radioactive decay |
process where an unstable nucleus changes energy states and in the process emits radiation |
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alpha particle |
particle that makes up alpha rays; it is identical to the helium nucleus and is composed of two protons and two neutrons |
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beta particle |
the particle that makes up beta rays; it is identical to an electron but is produced in the nucleus when a neutron is changed into a proton and an electron |
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gamma ray |
high energy ray that is like an X ray but with a higher energy |
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radioisotope |
an isotope of an element that emits nuclear radiation |
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daughter nuclei |
the new nuclei produced when unstable nuclei undergo radioactive decay |
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positron |
+ charged electron |
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electron capture |
mode of decay for some unstable nuclei where an electron from outside the nucleus is drawn into the nucleus, where it combbines with a proton to form a neutron |
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half life |
time required for one half the unstable nuclei in a sample to undergo radioactive decay |
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radical or free radical |
electron deficient particle that is very reactive |
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acute radiation syndrome |
condition associated with and following short term exposure to intense radiation |
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inverse square law of radiation |
mathematical way of saying that the intensity of radiation is inversly proportional to the square of the distance from the source of the radiation |
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physical unit of radiation |
radiation measurement unit indicating the activity of the source of the radiation; ex. number of nuclear decays per minute |
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biological unit of radiation |
radiation measurement unit indicating the damage caused by radiation in living tissue |
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curie |
physical unit of radiation measurement corresponding to 3.7 x 10^10 nuclear disintegrations per second |
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becquerel |
physical unit of radiation measurement corresponding to one nuclear disintegration per second |
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roentgen |
biological unit of radiation measurement used with X rays and gamma rays; the quantity of radiation that generates 2.1 x 10^9 ion pairs per 1cm^3 of dry air or 1.8 x 10^12 ion pairs per 1 g of tissue |
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rad |
biological unit unit of radiation measurement corresponding to the transfer 1 x 10^-2 J or 2.4 x 10^-3 cal of energy to 1 kg of tissue |
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gray |
biological unit of radiation measurement corresponding to the transfer of 1 J of energy to 1 kg of tissue |
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rem |
biological unit of radiation measurement corresponding to the health effect produced by 1 roentgen of gamme or X rays regardless of the type of radiation involved |
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scintillation counter |
radiation detection device operating on the principle that phosphors give off light when struck by radiation |
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Geiger-Muller tube |
radiation detection device operating on the principle that ions form when radiation passes through a tube filled with low pressure gas |
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tracer |
radioisotope used medically because its progress through the body or localization in specific organs can be followed |
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hot spot |
tissue in which a radioactive tracer concentrates |
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cold spot |
tissue from which a radioactive tracer is excluded or rejected |
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radioactive dating |
process for determining the age of artifacts and rocks based on the amount and half life of radioisotopes contained in the object |
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moderators |
materials capable of slowing down neutrons that pass through them |
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cyclotron |
cyclic particle accelerator that works by changing electrical polarities as charged particles cross a gap; the particles are kept moving in a spiral path by a strong magnetic field |
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linear accelerator |
particle accelerator that works b changing electrical polarities as charged particles cross gaps between segments of a long tube |
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transuranium elements |
synthetic slements with atomic numbers greater than that of uranium |
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nuclear fission |
process where large nuclei split into smaller, app equal sized nuclei when bombarded by neutrons |
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chain reaction |
nuclear reaction where the products of one reaction causes a repeat of the reaction to take place; in the case of uranium fission, neutrons from fission reactions cause other fission reactions to occur |
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expanding or branching chain reaction |
reaction where the products of one reaction cause more than one more reaction to occur |
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critical reaction |
constant rate chain reaction |
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supercritical reaction |
branching chain reaction |
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critical mass |
minimum amount of fissionable material needed to sustain a critical chain reaction at a constant rate |
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supercritical mass |
minimum amount of fissionable material that must be present to cause a branching chain reaction to occur |
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breeder reaction |
nuclear reaction where isotopes that will not undergo spontaneous fission are changed into isotopes that will |
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thermonuclear reactions |
nuclear fusion reactions that require a very high temperature to start |
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nuclear fusion |
process where small nuclei combine or fuse to form larger nuclei |
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