New Experimentally Observable Gamma-ray Emissions from 241Am Nuclear Decay.

With the high resolution of microcalorimeter detectors, previously unresolvable gamma-ray lines are now clearly resolvable. A careful measurement of 241Am decay with a large microcalorimeter array has yielded never before seen or predicted gamma lines at 207.72 +/- 0.02 keV and 208.21 +/- 0.01 keV. These have been made possible because of new microwave-multiplexing readout and improved analysis algorithms for microcalorimeters.