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Unformatted text preview: NE-524 Interaction of radiation with Matter Problem Set #5 (Complete by 11/13/2005)
1) A beam of 0.52 MeV electrons pass into a large reservoir of He at 3 atm pressure, 20 oC (electrons are totally absorbed). a) What is the range of the electrons? b) What is the average total radiative loss (eV/electron)? c) What is the total ionization produced in He (ion pairs/electron)? Estimate the rate of energy loss due to ionization of 2 MeV electrons passing through silver in MeV/cm and MeV.g/cm2. What is the stopping power of 600 keV electrons in water? Calculate the range of Y-90 betas (Emax = 2.27 MeV) in bone (=1.9 g/cc). A health physicist finds an unknown contaminant that turns out to be a pure beta emitter. Using a GM tube with a mica window 0.1 mm thick (r=2.7 g/cc), he finds that 1.74 mm of Al stops all betas. If the distance between the sample and the detector was 2 cm, what is the energy of the beta and what is the contaminant? 2) 3) 4) 5) Answers:
1) a) 346 cm, b) 325 eV/electron, c) 12,583 ion pairs / electron 2) 12.9 MeV/cm, 1.23 MeV.cm2/g 3) 2.014 MeV/cm 4) 0.574 cm 5) 1.177 MeV, Bi-210 ...
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- Fall '08