1.1 This test method covers procedures for measuring reaction rates by the activation reaction 63Cu(n,alpha)60Co. The cross section for 60Co produced in this reaction increases rapidly with neutrons having energies greater than about 5 MeV. 60Co decays with a half-life of 1925.1 days (177; 0.5 days) and emits two gamma rays having energies of 1.1732 and 1.3325 MeV3. The isotopic content of natural copper is 69.17 % 63Cu and 30.83 % 65Cu. The neutron reaction, 63Cu(n,947;)64Cu, produces a radioactive product that emits gamma rays 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,alpha)60Co reaction can be used to determine fast-neutron fluences for irradiation times up to about 15 years (for longer irradiations, see Practice E 261).
1.3 Detailed procedures for other fast-neutron detectors are referenced in Practice E 261.
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.
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