Effects of linear polarization and Doppler broadening on the exposure buildup factors of low-energy gamma rays

Journal Article · Sat Jul 01 04:00:00 EDT 1995 · Nuclear Science and Engineering

OSTI ID:89681

Namito, Y; Ban, S; Hirayama, H ^[1]

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1. National Laboratory for High Energy Physics, Tsukuba (Japan)

The effects of including linear polarization and Doppler broadening of the Compton-scattered photon energy, i.e., the Compton profile, in a calculation of the exposure buildup factors for plane normal gamma-ray sources are investigated by using an improved electron gamma shower Monte Carlo code, EGS4, for water, iron, and lead in the 40- to 250-keV range for penetration depths of up to 16 mean free paths (mfp). The effects of including the bound Compton total cross section ({sigma}{sub bC}) and the bound Compton-scattered photon angular distribution by using the incoherent-scattering function [S(x, Z)] were also evaluated. The ``pseudo`` exposure buildup factors were calculated to determine these effects combined with the effects of Rayleigh and/or Compton scattering. The pseudo exposure buildup factor increases at points farther than a few mfp`s and decreases in the neighborhood of the source upon including linear polarization. It decreases upon including Doppler broadening. The degree of each effect varies with the atomic number of the material. The effect of linear polarization is large for materials of small atomic number; that of the Doppler broadening is large for materials of medium and large atomic number.

• OSTI ID: 89681
• Journal Information: Nuclear Science and Engineering, Journal Name: Nuclear Science and Engineering Journal Issue: 3 Vol. 120; ISSN NSENAO; ISSN 0029-5639
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
BUILDUP
COMPTON EFFECT
E CODES
GAMMA RADIATION
IRON
KEV RANGE 10-100
KEV RANGE 100-1000
LEAD
PHOTON TRANSPORT
WATER