So, a gamma ray is essentially a helium nucleus
Nobelium 102 is not an isotope. The 102 refers to the atomic number. The isotope would be Nobelium-254, Nobelium-250, Nobelium 264, etc.
When you find the correct isotope, it will emit a helium nucleus and a new element with a mass 4 less and a number 2 less, if it exists at all.