Mass spectrometric determinations for trace amounts of radioactive
54 Mn and
53Mn in the presence of
55Mn have been studied. Both
54Mn and
53Mn are readily produced by nuclear reactions. Absolute amounts of each isotope could be obtained from the disintegration rate of
54Mn and the isotope ratios of
54Mn to the others. In order to find suitable experimental conditions in the isotope ratio, measure ments, a commercially available“ carrier-free
54Mn” was used as the sample.
The manganese fraction was extracted from the sample containing 10
7 dpm of
54Mn and was puri fied for our mass spectrometric measurements by a wet chemical method. A silica gel method was applied for the solid source surface ionization and a pulse-counting method was improved to measure the extremely weak ion beam current. In one run about 10
11 atoms of
54Mn could be determined with a high reproducibility in the presence of about 10
14 atoms of
55Mn. Furthermore, coexisting
53Mn at the level of 10
10 atoms could also be detected with about±10%error.
This method has been applied to determine the production cross-sections of
54Mn and
53Mn induced in a cyclotron-irradiated iron target.
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