1.1This test method covers procedures measuring reaction rates by the activation reaction ²⁷Al(n,α)²⁴Na.

1.2This activation reaction is useful for measuring neutrons with energies above approximately 6.5 MeV and for irradiation times up to about two days (for longer irradiations, or when there are significant variations in reactor power during the irradiation, see Practice E261).

1.3With suitable techniques, fission-neutron fluence rates above 10⁶ cm⁻²·s⁻¹ can be determined.

1.4Detailed procedures for other fast neutron detectors are referenced in Practice E261.

1.5This 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.