Let $X_1, X_2, \ldots \ldots X_{18}$ be eighteen observations such that $\sum_{i=1}^{18}\left(x_i-\alpha\right)=36$ and $\sum_{i=1}^{18}\left(x_i-\beta\right)^2=90$, where $\alpha$ and $\beta$ are distinct real numbers. If the standard deviation of these observations is 1 , then the value of $|\alpha-\beta|$ is $\_\_\_\_$ .