Measurement of the ^{229}Th Isomer Energy with a Magnetic Microcalorimeter.

  title={Measurement of the ^\{229\}Th Isomer Energy with a Magnetic Microcalorimeter.},
  author={Tomas Sikorsky and Jeschua Geist and Daniel Hengstler and Sebastian Kempf and Loredana Gastaldo and Christian Enss and Ch. Mokry and J{\"o}rg Runke and Christoph Emanuel D{\"u}llmann and Peter Wobrauschek and Kjeld Beeks and Veronika Rosecker and Johannes H. Sterba and G A Kazakov and Thorsten Schumm and Andreas Fleischmann},
  journal={Physical review letters},
  volume={125 14},
We present a measurement of the low-energy (0-60 keV) γ-ray spectrum produced in the α decay of ^{233}U using a dedicated cryogenic magnetic microcalorimeter. The energy resolution of ∼10  eV, together with exceptional gain linearity, allows us to determine the energy of the low-lying isomeric state in ^{229}Th using four complementary evaluation schemes. The most precise scheme determines the ^{229}Th isomer energy to be 8.10(17) eV, corresponding to 153.1(32) nm, superseding in precision… 

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