Why do beta gauges have noise in their measurement?
This is due to the fact that the decay of an atom is a random event. If we have say 1000 atoms, each with a half life of 1 year, then over the course of a year, we would expect half of them (500) to decay. But not exactly 500 of them will decay. It gets a little technical, but bear with us… The standard deviation of the number which will decay is equal to the square root of the expected number. The square root of 500 is about 22. That means that, 67% of the time, we would expect 500 +/- 22 atoms to decay, or anywhere from 478 to 522 atoms. So, if we place a material in the beam that only stops say 10% of the beta particles, then it stops 50 of them, and we would expect to count 450 particles, with a standard deviation of 21. But it’s clear that there really might be 429 to 471 particles, one standard deviation is 4.8%. The randomness of the number of beta particles detected is large compared to the change caused by the material. So we cannot make a good measurement. By increasing the
