Abstract
We report a high-statistics measurement of the L/K orbital electron capture ratio in Be7 embedded in cryogenic Ta. The thin Ta film formed part of a high-resolution superconducting tunnel junction radiation detector that was used to identify the signals from different decay channels. The measured L/K capture ratio of 0.070(7) is significantly larger than the only previous measurement of this quantity and the theoretical predictions that include in-medium effects. This value is a uniquely sensitive probe of the 1s and 2s orbital overlaps with the nucleus and is of relevance to nuclear and atomic physics, as well as Li production in novae and other astrophysical scenarios. This is the first experiment that uses superconducting tunnel junctions for nuclear-recoil detection, opening a new experimental avenue for low-energy precision measurements with rare isotopes.
| Original language | English |
|---|---|
| Article number | 032701 |
| Journal | Physical Review Letters |
| Volume | 125 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jul 17 2020 |
| Externally published | Yes |
Funding
This work was funded by the Lawrence Livermore National Laboratory Lab Directed Research and Development program through Grants No. 19-FS-027 and No. 20-LW-006 and the U.S. Department of Energy, Office of Science under Award No. DE-SC0017649. TRIUMF receives federal funding via a contribution agreement with the National Research Council of Canada. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The theoretical work was performed as part of the European Metrology Programme for Innovation and Research (EMPIR) Project No. 17FUN02 MetroMMC. This project has received funding from the EMPIR program cofinanced by the participating states and from the European Union’s Horizon 2020 research and innovation program. We would like to thank Friedhelm Ames, Louis Clark, Peter Kunz, Jens Lassen, and Brad Schultz for their efforts in facilitating the ion-beam implantation. K. G. L. also thanks Tibor Kibedi, Uwe Greife, John Behr, Fred Sarazin, Vladan Stefanovic, Mark Lusk, Xerxes Stirer, and Jeramy Zimmerman for useful discussions.