Swift heavy ion

If the irradiation is carried out in an initially crystalline material, ion tracks consist of an amorphous cylinder.

Heavy ion beams are generally described in terms of their energy in Mega electron volts (MeV) divided by the mass of the atomic nucleus, written "MeV/u".

They can be considered to produce thermal spikes[4][5] in the sense that they lead to strong lattice heating and a transient disordered atom zone.

However, at least the initial stage of the damage might be better understood in terms of a Coulomb explosion mechanism.

[6] Regardless of what the heating mechanism is, it is well established that swift heavy ions typically produce a long nearly cylindrical track of damage in insulators,[1][4] which has been shown to be underdense in the middle, at least in SiO2.

Four atomic scale images of a SHI track in quartz at different times
Time evolution of a Molecular Dynamics simulation of a swift heavy ion track in crystalline quartz, producing a cylindrical amorphous track in the material. Image size 17 nm × 13 nm.