Isotopic Effects in the X-Ray Spectrum of Muonic Atoms ofCa40andCa44

The $2p\to 1s$ is transitions in muonic atoms of ${\mathrm{Ca}}^{44}$ and ${\mathrm{Ca}}^{40}$ were compared by use of a NaI(Tl) scintillation spectrometer with an anticoincidence annulus of NaI(Tl). It was found that the energy of the $2p\to 1s$ transition in ${\mathrm{Ca}}^{40}$ is 0.9±0.3 keV greater than that in ${\mathrm{Ca}}^{44}$.