Method for Determining theK+0−K−0Mass Difference

The equations of motion for the amplitudes of short-lived (${K_{+}}^0$) and long-lived (${K_{-}}^0$) neutral $K$ mesons in an absorber are simplified for the case of dominance of the decay term. For the case of a thick absorber, a simple relation between the intensities of scattered and unscattered regenerated ${K_{+}}^0$, at zero degrees, results; the relation is sensitive to the ${K_{+}}^0-{K_{-}}^0$ mass difference.