Provided herein are systems and methods for generating a plurality of different monoenergetic neutron energies using a plurality of interchangeable ion beam targets. In certain embodiments, each of the plurality of ion beam targets is configured to generate a monoenergetic energy value that is at least 100 kiloelectron volts (keV) different from the other ion beam targets. In some embodiments, the ion beam targets are composed of LiF, TiD1.5-1.8, TiT1-2, ErD1.5, ErT, or Li.