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1.1 This test method covers procedures for measuring reaction rates by the activation reaction 63Cu(n,α) 60Co. The cross section for 60Co produced in this reaction increases rapidly with neutrons having energies greater than about 4.5 MeV. 60Co decays with a half-life of 1925.27 days (±0.29 days)() and emits two gamma rays having energies of 1.1732278 and 1.332492 MeV(. The isotopic content of natural copper is 69.17 % 63Cu and 30.83 % 65Cu )(. The neutron reaction, 63Cu(n,γ)64Cu, produces a radioactive product that emits gamma rays (1.34577 MeV ( ) )) which might interfere with the counting of the 60Co gamma rays.
1.2 With suitable techniques, fission-neutron fluence rates above 109 cm−2·s−1 can be determined. The 63Cu(n,α)60Co reaction can be used to determine fast-neutron fluences for irradiation times up to about 15 years, provided that the analysis methods described in Practice are followed. If dosimeters are analyzed after irradiation periods longer than 15 years, the information inferred about the fluence during irradiation periods more than 15 years before the end of the irradiation should not be relied upon without supporting data from dosimeters withdrawn earlier.
1.3 Detailed procedures for other fast-neutron detectors are referenced in Practice .
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
|Engelse titel||Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Copper|