Thermal neutron macroscopic absorption cross section measurement (theory, experiment and results) for small environmental samples
- Henryk Niewodniczanski Institute of Nuclear Physics, Krakow (Poland)
Czubek`s method of measurement of the thermal neutron macroscopic absorption cross section of small samples has been developed at the Henryk Niewodniczanski Institute of Nuclear Physics in Krakow, Poland. Theoretical principles of the method have been elaborated in the one-velocity diffusion approach in which the thermal neutron parameters used have been averaged over a modified Maxwellian. In consecutive measurements the investigated sample is enveloped in shells of a known moderator of varying thickness and irradiated with a pulsed beam of fast neutrons. The neutrons are slowed-down in the system and a die-away rate of escaping thermal neutrons is measured. The decay constant vs. thickness of the moderator creates the experimental curve. The absorption cross section of the unknown sample is found from the intersection of this curve with the theoretical one. The theoretical curve is calculated for the case when the dynamic material buckling of the inner sample is zero. The method does not use any reference absorption standard and is independent of the transport cross section of the measured sample. The volume of the sample is form of fluid or crushed material is about 170 cm{sup 3}. The standard deviation for the measured mass absorption cross section of rock samples is in the range of 4 divided by 20% of the measured value and for brines is of the order of 0.5%.
- OSTI ID:
- 68109
- Report Number(s):
- CONF-940507-Vol.1; CNN: Contract 4121/RB; TRN: 95:002915-0037
- Resource Relation:
- Conference: International conference on nuclear data for science and technology: nuclear data for the twenty-first century, Gatlinburg, TN (United States), 9-13 May 1994; Other Information: PBD: 1994; Related Information: Is Part Of Proceedings of the international conference nuclear data for science and technology. Volume 1; Dickens, J.K. [ed.]; PB: 592 p.
- Country of Publication:
- United States
- Language:
- English
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