HW13-6 - 7-4 Radiation Interactions Chap.7 6 Calculate the...

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Unformatted text preview: 7-4 Radiation Interactions Chap.7 6. Calculate the linear interaction coefficients in pure air at 20°C and 1 atm pressure for a I-MeV photon and a thermal neutron (2200 m S-I). Assume that air has the composition 75.3%nitrogen, 23.2%oxygen, and 1.4% argon by mass. Use the following data: Element Nitrogen Oxygen Argon Solution: The density of dry air at standard conditions is Pair = 0.0012 gfcm3, The atom density of the elementscomprising air are Ni = Wi PairNa 0.0636 0.0636 11.9 4.2 2.2 0.0574 A (P7.1) where Wi is the mags fraction of the ith element (i = N, 0, Ar). Photons: Use the gamma-ray data in Ap. C to obtain = 0.0012[(0.153)(0.0636) (0.232)(0.0636)+ (0.014)(0.0514)] + = 7.61 X 10-5 cm-l. Neutrons: obtain . L = .i -iO't Use the neutrons cross section data in Ap. C and Eq. (P7.1) to f i J.tn a~r i = N~O'tPairNa L -:.A~ ~ [ (0.753)(11.9) 14.007 + (0.232)(4.2) 15.9994 + (0.014)(2.2) 39.948 ] (0.0012)(0.6022) = 5.07 X 10-4 cm- July 24, 2002 ...
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This note was uploaded on 02/01/2010 for the course ECE 4130 taught by Professor Cady during the Spring '06 term at Cornell.

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