Variation of environmental neutron flux with altitude and depth of both water and soil

MISCELLANEOUS

Variation of environmental neutron flux with altitude and depth of both water and soil

K. KOMURA，

N.K. AHMED，

A.H. EL-KAMEL，

A.M.M. YOUSEF

Nuclear Science and Techniques

Vol.15, No.4

pp.248-256

Published in print 01 Aug 2004

CLC：X125,TL816

23100

Applying the extreme low-level γ-ray spectroscopic analysis the environmental neutron flux is measured using different moderator construction and environment through the reaction ¹⁹⁷Au (n, γ) ¹⁹⁸Au. The contribution of thermal and resonance neutrons is separated using the cadmium difference technique, while fast neutrons are measured by the paraffin moderator. The results of altitude dependence of the neutron flux are discussed. The thermal neutron flux near the surface of sea water is less than its value at 100 cm over ground near sea water, while the value over the surfaces of fresh water is higher than that near the surface of sea water. Also the thermal neutron flux at 5 cm soil depth increases, then decreases to its original value at 10 cm depth and still constant until 25 cm, then decreases rapidly to reach 27% of its original value at 60 cm depth. The soil compositions, corresponding neutron temperatures and effective absorption cross sections of earth are the most effective factors on the equilibrium region of thermal neutrons in the ground.

Extreme low-level γg-ray spectroscopyEnvironmental neutron fluxGold activation

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