# Which types of particles are affected by the wave-particle duality?

If we take the double slit experiment as a way of demonstrating the wave-particle duality, which types of particles would show an interference pattern?

For example, I know that electrons show such a pattern. But do protons, too? What about atoms? Where is the boundary between "wavey particles" and "classical particles"?

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The largest thing I have heard of is buckyballs: univie.ac.at/qfp/research/matterwave/c60 –  DJBunk Mar 11 '14 at 22:39
Wow, this is impressive! –  buschtoens Mar 12 '14 at 12:39

$$\lambda = \frac{h}{p}$$
where $h$ is the Planck constant and $p$ is the object momentum. For an object moving at non-relativistic speeds you may remember that the momentum is defined as $\vec{p}=m\vec{v}$; the De Broglie wavelength is then inversely proportional to the object mass. The bigger an object is, the less relevant its wave-like nature is, and that's why in everyday experience we are not used to observing the wave-like nature of massive objects.