Exercises in Nuclear Physics Universit Leipzig

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					Dr. Daniel Spemann                                                                            WS 2012/13
Nukleare Festk¨rperphysik                                                                         Sheet 7
      a u
Fakult¨t f¨r Physik und Geowissenschaften
Universit¨t Leipzig

                              Exercises in Nuclear Physics

Task 1: (6 points)
                                                hot spot
A “hot spot” is a strong radioactive source, possibly of just one certain isotope, with very strong specific
activity and the size of a dust particle. A punctual “hot spot” of 106 Ru is fixed at a certain point of the
lung and irradiates the tissue there hemispherically. 106 Ru is a 40 keV-β-source with a half-life T1/2 =
367 d. The activity of the “hot spot” is 100 µCi and the penetration depth of the radiation is 0.1 mm
                                         0,1 mm
in average. Calculate the number of 106 Ru atoms of the “hot spot” and the energy dose the surrounding
tissue is exposed to (human tissue mainly consists of water).

                                                hot spot

                                                              lung tissue
                                       0.1 mm

Task 2: (5 points)
The decay of 57 Co via electron capture to the 57 Fe ground state has two intermediate states (see decay
scheme). What are the multipolarities l and types (E,M) of γ-radiation emitted in the two transitions in
the 57 Fe nucleus? Which of them are the most probable ones?

Task 3: (10 points)
In the Pound-Rebka-experiment the M¨ßbauer-effect was used to determine the wavelength shift of γ-
quanta in the gravitational field of the earth.

 a) What is the relative frequency shift of a γ-quantum in the gravitational field of the earth for a
    height difference of h = 23 m between source and absorber?
 b) Compare this result with the natural line width of the 14.4 keV γ-line of the transition in the 57 Fe
    (half-life of the excited state T1/2 = 98 ns)!
 c) In the experiment a 57 Co source with an activity of 0.4 Ci was used. How many 14.4 keV γ-quanta
    can be expected at the absorber per second (distance h = 23 m, diameter d = 7.62 cm), if a scattering
    of the quanta between source and absorber can be neglected?

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