6533b85dfe1ef96bd12bdbdc
RESEARCH PRODUCT
Measurement of the Th229 Isomer Energy with a Magnetic Microcalorimeter
Andreas FleischmannChristoph E. DüllmannC. MokryChristian EnssGeorgy A. KazakovJörg RunkeSebastian KempfPeter WobrauschekThorsten SchummVeronika RoseckerTomas SikorskyTomas SikorskyJeschua GeistD. HengstlerJohannes H. SterbaLoredana GastaldoKjeld Beekssubject
PhysicsExcited state0103 physical sciencesGeneral Physics and AstronomyLinearityElectronAtomic physics010306 general physicsSpectroscopy01 natural sciencesNuclear theorydescription
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 previous values based on γ spectroscopy, and agreeing with a recent measurement based on internal conversion electrons. We also measure branching ratios of the relevant excited states to be b_{29}=9.3(6)% and b_{42}<0.7%.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2020-09-28 | Physical Review Letters |