Speaker
Description
High-precision Q value determination of the $^7\text{Be}$ decay through Penning-trap mass measurements
Julius Franke, Sergey Eliseev, Christoph Schweiger, Pavel Filianin, Jan Nägele, Finn Mehlhorn, Nils Bock, Burcu Cakirli and Klaus Blaum for the PENTATRAP experiment - Max Planck Institute for Nuclear Physics, Heidelberg
The cryogenic Penning-trap mass spectrometer PENTATRAP, located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, achieves mass-ratio determinations with relative uncertainties in the low $10^{-12}$ range [1]. This is made possible by measuring the free-space cyclotron frequency of highly charged ions (HCI) confined in a stack of five cylindrical Penning traps within a homogeneous $7\;\mathrm{T}$ magnetic field, utilizing a non-destructive image current detection system. PENTATRAP has contributed with high-precision mass-ratio measurements in several fields of fundamental physics with applications in atomic, nuclear and neutrino physics. Notably, the setup features access to two Electron Beam Ion Traps serving as external sources for HCI. They both employ in-trap laser-induced desorption, a system specifically suited for the injection of very rare nuclides.
This contribution will focus on the planned Q value determination of the electron capture decay process of $^7\text{Be}$. At PENTATRAP, the Q value is determined from a measurement of the free-space cyclotron frequency ratio of HCI of $^7\text{Be}$ and its daughter nuclide $^7\text{Li}$. The binding energy difference of the missing electrons in both HCI is taken into account using precisely measured atomic binding energies, which for these few-electron systems are experimentally accessible with sufficient precision. The Q value is crucial for the BeEST [2] experiment, which performs a model-independent kinematic study of the decay in the search for sterile neutrinos in the $\mathrm{keV}$ mass range. To prevent the Q value uncertainty from limiting the experimental sensitivity, we aim to achieve sub-$\mathrm{eV}$ precision, corresponding to atomic mass-ratio measurements with relative uncertainties at the few times $10^{-12}$ level. Efficient preparation and handling of samples containing extremely small quantities, in the tens of nano grams range, of the synthetic radioisotope $^7\text{Be}$ are essential due to its limited availability. We will explore ion implantation at a radioactive ion beam facility as a potential method for producing such a target.
[1] Schweiger, Ch., et al., Nat. Phys. 20, 921, (2024)
[2] Leach, K.G. et al., J. Low. Temp. Phys. 209, 796 (2022)
| Academic level | PhD student |
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