Standard Test Method for Measuring Reaction Rates and Fast-Neutron Fluences by Radioactivation of Sulfur-32

5.1 Refer to Guides E720 and E844 for the selection, irradiation, and quality control of neutron dosimeters.

5.2 Refer to Practice E261 for a general discussion of the determination of fast-neutron fluence and fluence rate with threshold detectors.

5.3 The activation reaction produces ³²P, which decays by the emission of a single beta particle in 100 % of the decays, and which emits no gamma rays. The half life of ³²P is 14.262 (14)³ days (1) ⁴ and the maximum beta energy is 1710 keV (2).

5.4 Elemental sulfur is readily available in pure form and any trace contaminants present do not produce significant amounts of radioactivity. Natural sulfur, however, is composed of ³²S (95.02 % (9)), ³⁴S (4.21 % (8)) (1), and trace amounts of other sulfur isotopes. The presence of these other isotopes leads to several competing reactions that can interfere with the counting of the 1710-keV beta particle. This interference can usually be eliminated by the use of appropriate techniques, as discussed in Section 8.