Radioactivation analysis of silicon and aluminum with 14 MeV neutrons

Abstract

A rapid and nondestructive activation analysis of silicon and aluminum in silicate was proposed, by means of ²⁸Si(n, p)²⁸Al and ²⁷Al(n, p)²⁷Mg reactions caused by 14 MeV neutron irradiation.
A sample(3 g) in a polyethylene rabbit and a quartz neutron monitor were irradiated simultaneously for 3 min. with 14 MeV neutrons produced by T-d reaction in a Cockcroft-Walton neutron generator, and then the induced radioactivities were measured by a well type scintillation detector. A multichannel analyzer or two single-channel pulse height analyzers were used for counting the ²⁸Al and the ²⁷Mg photopeaks. One minute's counting after 3.5 min. cooling was adopted for silicon, and 3 or 4 min. counting after 25 min. cooling for aluminum. The radioactivities were normalized with the activity induced in the monitor, and then silicon and aluminum were determined, referring to the calibration curve.
The determination of aluminum was interfered from ⁵⁶Mn introduced by (n, p) reaction of iron as a sample constituent, and the result should be corrected for this by counting ⁵⁶Mn at 1 hr. after the ²⁷Mg counting.
The analytical errors by this method were 2% for silicon and 4% for aluminum, under the neutron flux 1× 10⁷ n/cm²/sec.