10 Radioactive Decays

Modern Physics

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PHY251 - Radioactive Decays PHY 251 Radioactive Decays Introduction In this experiment we will measure the half-life of an excited state of the 137 Ba nucleus. Samples are prepared from a radioactive isotope of 137 Cs. This isotope has too many neutrons to be stable; it decays by β -decay into 137 Ba * . This daughter nucleus is produced in an excited state, indicated by the asterisk (*). The excited state subsequently decays into the ground state of 137 Ba with a half-life of the excited state of 2.6 min. The decay of the excited state is detected by measuring the emitted γ -rays of 0.66 MeV. This energy corresponds exactly to the energy difference between the excited state in 137 Ba * and the ground state. Cesium decay Figure 1: The 137 Cs decay chain. The γ -ray emission rate R ( t ) = - dN ( t )/ dt , where N ( t ) is the number of 137 Ba * nuclei present at time t . The emission rate is proportional to N ( t ): dN ( t )/ dt = - λ N ( t ) , where the proportionality factor λ is defined as the decay constant. Integration of above expression leads
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This lab report was uploaded on 02/05/2008 for the course PHY 251 taught by Professor Rijssenbeek during the Fall '01 term at SUNY Stony Brook.

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10 Radioactive Decays - PHY251 Radioactive Decays PHY 251...

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