Does heavy related to the elemental mass no. or that the velocity is reativistic (i.e speed of light) that mass and energy are correlated.. anybody specify..
There are two part of question: any ion which is heavier than alpha (2He4) is treated as HEAVY. When people talk about swift heavy ion irradiation - its also related to velocity but has nothing to do with the relativisticness. An AMeV range ion (A>4) is swift heavy ion. Let me know it works for you.