SAM III Series | What is the sigma trigger setting for?

The sigma trigger allows a low threshold for sensing a radioactive source while being unaffected by false triggering due to changes in background (sigma indicates standard deviations over background).  This provision automatically updates the current background which yields higher sensitivity while eliminating false triggers due to changing ambient background.  This feature allows the user to survey a large area without needing to continuously stop and store a new and different background.  A sigma setting of 4 is recommended.