URGENT:PLEASE HELP:VADER MODEL

Hello everyone, I am in a complete disaster right as in I can't find solution for my Degree Project. 

Does anyone know how VADER model works? It is a sentiment operator inside RapidMiner.

I mean not just how it gives intensity of words but how exactly VADER model works, what is the algorithm, how does it determine negativity of a word stuff like that? In details. 

If any of you find articles or has research upon this please do let me know. My whole degree is depending on this. Thanks in advanced.