Biomaterial Database

Neutron flux self-shielding in activation analysis. 1980

T Takeuchi

Some effects of self-shielding of neutron flux in neutron activation analysis have been investigated. Induced specific activities in dilute samples were compared with those in solid elements irradiated under the same conditions. Two factors affecting the neutron flux were investigated: thermal neutron self-shielding and epithermal neutron self-shielding. The former effect can be computed reasonably accurately, using a well-known approximation. Self-shielding of epithermal neutrons cannot be calculated rigorously, so an empirical approach was used. The self-shielding effects of neutron flux were evaluated for uranium and a maximum permissible weight has been calculated by assuming that the product of the maximum permissible weight and the atom density is a function of the ratio of the resonance integral of the absorbing element to that of uranium.

UI	MeSH Term	Description	Entries
D009501	Neutron Activation Analysis	Activation analysis in which the specimen is bombarded with neutrons. Identification is made by measuring the resulting radioisotopes. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Activation Analysis, Neutron,Analysis, Neutron Activation,Activation Analyses, Neutron,Analyses, Neutron Activation,Neutron Activation Analyses
D009502	Neutrons	Electrically neutral elementary particles found in all atomic nuclei except light hydrogen; the mass is equal to that of the proton and electron combined and they are unstable when isolated from the nucleus, undergoing beta decay. Slow, thermal, epithermal, and fast neutrons refer to the energy levels with which the neutrons are ejected from heavier nuclei during their decay.	Neutron
D000201	Activation Analysis	A method of chemical analysis based on the detection of characteristic radionuclides following a nuclear bombardment. It is also known as radioactivity analysis. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Analysis, Activation,Activation Analyses,Analyses, Activation
D014501	Uranium	A radioactive element of the actinide series of metals. It has an atomic symbol U, atomic number 92, and atomic weight 238.03. U-235 is used as the fissionable fuel in nuclear weapons and as fuel in nuclear power reactors.