A negatively charged muon (mass 207 times the mass of an electron) is captured in a Bohr’s orbit of high principal quantum number (n). The atom thus formed is called mesic atom. The muon in high energy state cascades down to lower orbits by emitting photons.
(a) The emitted photons are X rays. Why?
(b) Find the atomic number (Z) of a mu-mesic atom in which the orbit with `n = 1` will just touch the nuclear surface. Assume that the nucleus has equal number of protons and neutrons.

Answer

(b) `z = 48`