Nuclear fusion. Computer simulation sequence of gold & nickel nuclei joining (fusing) to make a nielsbohrium heavy nucleus. Each nucleus type has a specific number of positively-charged particles (protons). Gold has 79 protons (blue), & nickel 28 (red); neutrally-charged particles (neutrons) are grey/white in both nuclei. The nuclei collide & fuse to make a nielsbohrium nucleus (107 protons). This nucleus is unstable and will quickly undergo radioactive decay. Image based on data from the Separator for Heavy Ion reaction Products (SHIP) at the Society for Heavy Ion Research (GSI), Darmstadt, Germany.