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Definition
| defined as the time it takes for internally deposited radioactive material to be reduced to one-half of the initially deposited activity. Relative to the biological half-life or the radioactive half-life, the effective half-life is always less than both. |
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Term
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Definition
(Teff)of a radionuclide can be determined by multiplying the radioactive (T1/2)and biological (Tb)half-life of the nuclide together and then dividing by the sum of the radioactive and biological half-life of the nuclide.
Teff=(T1/2 x Tb)/(T1/2 + Tb) |
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Definition
The mathematical expression which expresses the relationship between the radioactive decay constant and the half-life of an isotope (to convert from half-life to decay constant or vice versa) is "t1/2 = 0.693/λ". That is the decay formula and uses λ as the decay constant.
"Both remain constant and are closely related" is a true statement regarding the relationship of the decay constant and the half-life.
The decay constant for a given radionuclide is equal to the natural log of 2 divided by the half-life of the radionuclide.
A curie is the amount of an element that decays at a rate of 3.7E10 disintegrations per second.
1 Ci = 3.7E10 DPS = 2.22E12 DPM |
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Definition
| the most difficult to shield. |
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Definition
| A thin sheet of paper can effectively shield Alpha. |
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Definition
| Water would be most effective material for attenuating neutron radiation, assuming all materials are the same thickness. |
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Term
| Half value layer/thickness |
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Definition
| defined as the thickness of a given material required to reduce the photon intensity to one-half the initial value (assuming no buildup). |
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Term
| The amount of shielding required to reduce a 2.5 R/hr gamma source to 2.5 mr/hr is |
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Definition
3 tenth-value layers.
For the same given thickness, lead would be the most effective for attenuating gamma radiation. |
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Term
| Tenth-value layers for a 1 Mev gamma |
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Definition
1.5 inches for Lead.
2 to 3 inches for Steel.
12 inches for concrete.
24 inches for water. |
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Term
| Tenth-value layers for a 6 Mev gamma |
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Definition
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Term
| Half-value layer thickness for 1 Mev gamma rays passing through steel |
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Definition
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Term
| Tenth value thickness for steel for Co-60 |
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Definition
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