lecture 5

lecture 5 - 1/17/2012 Health Physics Principles EEE 498,...

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1/17/2012 Lecture 1 1 Health Physics Principles EEE 498, EEE 591 Lecture 5 Radiation Sources: Transformation Kinetics, Activity Spring 2011, ASU R. Metzger, rlmetzger@asu.edu, GWC 387 Half Life Half life ( T or T 1/2 ): The time required for any given radioisotope to decrease to one-half of its original quantity. Example: P-32 has a half life of 14.3 days. Half lives range from microsecond to billion of years: T( 220 Rn)= 55.6 s T( 137 Cs)= 30.07 y T( 14 C)= 5730 y T( 238 U)= 4.46 X10 9 y T( 209 Bi)= 1.9 X10 19 y
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Lecture 1 2 Half Life The following relation is between the original activity (A 0 ) and the activity after n half-lives (A). Decrease of 32 P activity n A A 2 1 0 Transformation Constant Transformation Constant (decay constant), λ: where t in decay time and N is the number of radioactive atoms. Average Life (mean life), : The sum of the lifetimes of the individual atoms divided by the total number of atoms originally present. ; / 693 dt e t N t
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This note was uploaded on 02/11/2012 for the course EEE 498 taught by Professor Barnaby during the Spring '08 term at ASU.

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lecture 5 - 1/17/2012 Health Physics Principles EEE 498,...

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