Inverse Square law with gamma rays, Dudley college (May 2017)
Inverse Square law with $\gamma$ rays with Dudley Sixth Form college's students
On 3rd May, 2017, we welcomed Eric Jackson and his students (15) to discuss and study $\gamma$ rays using our Cs-137 radiosource here at Wolverhampton. After a general discussion of radiation, in particular its origins and associated safety issues, we started counting.
These are the results we obtained for this first demonstration of our setup (that still has to be improved, homed in our Physics lab and with optical bench to measure the distances). Camilo was in command, with assistance from some of the students for taking the data.
The main result, the inverse square law:
Our source behaves like a good point source as it clearly evidences the main feature, a uniform distribution of the radiated high-energy photons over a sphere.
We studied the statistical aspects as well. For two distances, at 3.44cm and 7.44cm, we get average counts of 793.8 and 193.3 per 30s, respectively. That's measuring slightly over twice farther and indeed the ratio of intensity drops by about 1/4, so inverse square (with roughly 13% accuracy).
The intensity fluctuates, which we have represented through histograms (not "instagrams", as French accent may incline you to mishear) and compared with the best estimators from our sampling, with a rather good agreement:
