Copper is often the target in an \(\mathrm{X}\) ray tube because of its high thermal conductiv ity. The target is typically mechanically rotated at several thousand revolutions per minute to average the heating effect of the electron beam. Copper's principal \(K_{\alpha}\) line has a wavelength of \(0.154 \mathrm{~nm}\). What is the shortest lattice spacing that can be observed by XRD using a copper target?