NSHAPE: Nuclear Shapes of Heavy Atoms and Proton-Emitting nuclei

The charge radius is one of the fundamental properties of the atomic nucleus upon which we build our
understanding of nuclear structure. It offers a great laboratory with which to test and improve our
understanding of nuclear structure, to design better models and predict the properties of nuclei that cannot
be studied in the laboratory, such as those found in exploding stars.
While great progress has been made in the last decades to study exotic radioisotopes by means of laser
spectroscopy at radioactive ion beam facilities, a crucial benchmark is missing to analyze data from
elements with an odd number of protons. Indeed, odd-Z elements only have 1 or 2 stable isotopes with
which the benchmarking experiments were performed in the 20th century, while 3 are required to complete
the process.
In particular, for potassium (Z=19) and silver (Z=47), new data has recently been collected that promises to
reveal great features of nuclear structure. An additional, radioactive benchmark is required. We thus
propose to perform muonic x-ray spectroscopy on the radioactive 40K and 108mAg isotopes at the Paul
Scherrer Institute, using the new muX spectrometer which allows such measurements for the first time.