EMQ Comment (l=14:13, 21 December 2010 (EST)) I fixed it for you.
Poisson distribution function
Calculations
We plotted the number of occurances verse the number of counts to obtain the graphs the manual asked us for. We also plotted the Poisson distribution function on each graph by using this formula.
[math]\displaystyle{ \Pr = \frac{e^{-\lambda} (\lambda)^k}{k!} }[/math]
For the graph of the 1000ms dwell time we also plotted the Gaussian distribution function to compare with our data as well as the Poisson distribution. As you can see they are very similar.
This is the Gaussian function we used.
The error in our graphs is because we chose to follow the manual and use the lowest number of channels. We used only 256. If we had used more channel we would have gotten more measurements, and therefore a better result. Despite this, all of our graphs except the 800ms and 1000ms graphs match the Poisson distribution closely.