Measurement of electron screening in muonic lead

Abstract

Energies of the transitions between high-lying ($n\ge 6$) states of muonic lead were accurately determined. The results are interpreted as a ∼2% test of the electron screening. The agreement between experiment and theory is good if it is assumed that the refilling of the electron $K$ shell is fast. The present results furthermore severely restrict possible ionization of the electron $L$ shell.