Probing Absolute Nuclear Charge Radii with Precision Muonic X-Ray SpectroscopyHYBRID

The knowledge of absolute nuclear charge radii has a significant scientific impact, from testing nuclear theories to beyond standard model physics. Using the muonic atom spectroscopy method, the absolute charge radii of almost all stable isotopes were extracted till the late 1990s. In this method, negative muons are stopped in a target material and subsequently captured into high atomic orbitals. From there on, the muon will cascade down to the ground state of the atom, emitting Auger electrons and muonic x rays. Due to the heavy mass of the muon, there is an enhanced overlap between the muonic states and the nuclear charge distribution making the low-lying muonic x rays a sensitive probe of the nuclear charge radius. However, to stop and capture the muon directly in the target, tenths to hundreds of milligrams of target material are typically needed, limiting past muonic measurements to stable or abundant targets. Since then, we have developed a method in which muon captures in microgram targets are realized through subsequent transfers of the muon in a high pressure H2/D2 gas, and thus we have extended the muonic measurements to radioactive and rare isotopes across the nuclear chart. At the same time, while standard semiconductor detectors are used for the muonic x-ray detection of heavier elements, their energy resolution limits the precision achievable for light systems. To probe the latter, the quantum sensing technology of metallic magnetic calorimeters has been employed instead. In this seminar, an overview of the muX, ReferenceRadii and QUARTET experiments and the current stage of charge radii extraction of isotopes spanning from Li to Cm will be discussed, highlighting the experimental and theoretical principles and challenges in that process.

https://gsi-fair.zoom.us/j/63856816325
Meeting-ID: 638 5681 6325
Passcode: AP_Seminar
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