Technological Development for Half-life Measurement of ¹⁴⁶Sm Nuclide

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Techniques for the measurement of the ¹⁴⁶Sm nuclide, which is known as an extinct nuclide on the present Earth, were developed in order to determine its half-life. The nuclide was produced in three reactions of ¹⁴⁷Sm (γ, n) ¹⁴⁶Sm, ¹⁴⁷Sm (n, 2n) ¹⁴⁶Sm, and ¹⁴⁷Sm (p, 2n) ¹⁴⁶Eu (→¹⁴⁶Sm). The Sm fraction in the target was chromatographically purified to prepare α counting samples as hydroxide. The ¹⁴⁶Sm/¹⁴⁷Sm α-activity ratios in the samples were measured using a Si surface barrier detector. The ¹⁴⁶Sm²²⁺/¹⁵²Sm²³⁺ and ¹⁴⁷Sm²²⁺/¹⁵²Sm²³⁺ ratios were measured by accelerator mass spectrometry using the ECR-ATLAS-GFM system. The ¹⁴⁶Sm ions were distinguished clearly from the other ions such as the abundant isobar, ¹⁴⁶Nd in the samples.