1. According to the Bohr model, what is the energy of a K beta x-ray photon and

Question

1. According to the Bohr model, what is the energy of a Kbeta x-ray photon and Lalpha x-ray photon for Molybdenum?

2. 10 mCi of 24Na (half-life is 14.95h) are to be produced through irradiation of stable 23Na in a nuclear reactor whose thermal neutron flux is 1011 n/cm2.s. The thermal neutron activation cross section for 24Na is 0.513 b. The irradiation time should not exceed 30 minutes. What is the minimum amount of 23Na (in gm) that should be irradiated to produce the 10 mCi of 24Na? (1 mCi = 3.7 x 107 Bq)

Explanation / Answer

1) According to the Bohr model,  Molybdenum characteristic x-ray energies: K-alpha radiation, at 17.9 keV, and K-beta, at 19.5 keV.

2)

10 mCi of 24Na (half-life is 14.95h) are to be produced through irradiation of stable 23Na in a nuclear reactor whose thermal neutron flux is 1011 n/cm2.s. The thermal neutron activation cross section for 24Na is 0.513 b. The irradiation time should not exceed 30 minutes. What is the minimum amount of 23Na (in gm) that should be irradiated to produce the 10 mCi of 24Na? (1 mCi = 3.7 x 107 Bq)

1/2)n = 0.25

n = 2 (remember (1/2)2 = 1/4 and 1/4 = 0.25)

12.26 x 2 = 24.52 years

Comment: the more general explanation follows:

(1/2)n = 0.25

n log 0.5 = log 0.25

n = log 0.25 / log 0.5

n = 2

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