[1] NIST, Ionizing Radiat Div, Phys Lab, Gaithersburg, MD 20899 USA
[2] NIST, Informat Technol Lab, Gaithersburg, MD 20899 USA
[3] NIST, Mfg Engn Lab, Gaithersburg, MD 20899 USA
[4] Miami Univ, Dept Phys, Oxford, OH 45056 USA
[5] Bruker Analyt GMBH, EPR Div, D-76827 Rheinstetten Karlsruhe, Germany
[6] Bruker Instruments Inc, EPR Div, Billerica, MA 01821 USA