Beta Decay of Cs137: Understanding Electron Count-Rate Distribution

[maroon]

I recently performed a Beta-decay experiment for a senior level lab course. I'm expected to write-up a report but I'm fairly confused as to some of the theory surrounding the Beta-decay of Cs137.

This experiment deals solely with negative Beta decay, of which the predominant form (94%) is decay into the meta-stable Ba137, which theoretically has a 2.55 min half-life. This form undergoes internal conversion to Ba137. Only emmitted electrons are being detected by the sensor.

When plotting electron count-rate vs Hall probe voltage (the set-up of this experiment entails the 180 degree deflection of emmitted electrons by way of a variable magnetic field-perpendicular to the movement plane), why is the distribution continuous?

I have a plot consisting of two peaks (both of which I understand why exist-I think), however I don't understand why the count-rate outside these regions is not zero.

Note that "background count" was accounted for, there was sufficient vacuum in the apparatus, and hysterisis (spelling?) was avoided.

I apologize in advance if my description is vague; It would be unreasonable for me to outline the entire lab in a forum post.

 

[maroon]

Anyone have any thoughts? I feel like I've really hit a wall here..

Thanks

 

[PhysicsGente]

Think about the way the detector "sees" an electron. That will tell you why the distribution is continuous.