Measurement of the $^{229}$Th isomer energy with a magnetic micro-calorimeter
| Autor: | Sikorsky, Tomas, Geist, Jeschua, Hengstler, Daniel, Kempf, Sebastian, Gastaldo, Loredana, Enss, Christian, Mokry, Christoph, Runke, J��rg, D��llmann, Christoph E., Wobrauschek, Peter, Beeks, Kjeld, Rosecker, Veronika, Sterba, Johannes H., Kazakov, Georgy, Schumm, Thorsten, Fleischmann, Andreas |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: | |
| Popis: | We present a measurement of the low-energy (0--60$\,$keV) $\gamma$ ray spectrum produced in the $\alpha$-decay of $^{233}$U using a dedicated cryogenic magnetic micro-calorimeter. The energy resolution of $\sim$$10\,$eV, together with exceptional gain linearity, allow us to measure the energy of the low-lying isomeric state in $^{229}$Th using four complementary evaluation schemes. The most accurate scheme determines the $^{229}$Th isomer energy to be $8.10(17)\,$eV, corresponding to 153.1(37)$\,$nm, superseding in precision previous values based on $\gamma$ 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 $b_{42}=0.3(3)\%$. Comment: 5 pages, 5 figures + supplementary |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|