Terrestrial thermal neutrons

Author

Dirk, LT John D ; Nelson, Martin E. ; Ziegler, James F. ; Thompson, Alan ; Zabel, Theodore H.

Volume

50

Issue

6

fYear

2003

Firstpage

2060

Lastpage

2064

Abstract

The first NIST-traceable measurements of environmental thermal neutrons have been completed. The average sea level flux of thermal neutrons is 4 cm²/hr. This flux changes less than two times over wide varieties of terrain, in all weather conditions and over the solar year. The neutron flux is normalized to 39N-76.5W. This flux scales with geomagnetic Lat/Long and with altitude in a manner similar to the flux of incident energetic cosmic rays. The shielded flux has been measured under 450 g/cm², with a residual flux of 0.1 times the sea-level value. Preliminary shielding studies inside buildings and under water shows significant variability in the thermal neutron mean attenuation coefficient.

Keywords

cosmic ray neutrons; geophysical aspects of cosmic rays; neutron flux; radiation hardening (electronics); average sea level flux; environmental thermal neutrons; incident energetic cosmic rays; shielded flux; solar year; terrestrial thermal neutrons; thermal neutron mean attenuation coefficient; weather conditions; Attenuation; Cosmic rays; Geomagnetism; Military computing; Neutrons; Nuclear electronics; Pollution measurement; Rain; Sea level; Sea measurements;

fLanguage

English

Journal_Title

Nuclear Science, IEEE Transactions on

Publisher

ieee

ISSN

0018-9499

Type

jour

DOI

10.1109/TNS.2003.821587

Filename

1263842