How Do Calibration Methods Differ Between Thin and Thick Silicon Detectors?

[indie452]

i am calibrating a detector set up using alpha particles to find resolution.
i have 2 silicon detectors a thin and thick one where the alpha is expected to pass through and lose energy in the first and be stopped by the second.

My handbook says i can find the energy resolution in the second thicker detector by using the standard FWHM/centroid and times this by alpha particle energy 5157KeV to get KeV resolution. then i can just take measurements from the face (front or back) of the detector with best resolution.

This i understand. But, for the first detector it is saying to plot a difference in the energy between the front and back face measurement, of which the width of this peak is the resolution of the detector. this i don't get at we generally choose a face to measure from in the actual experiment.

why is there two different methods?
is it because the particles pass through the first detector and because it has a thickness (in order to slow down the particle) there will be an energy difference between front and back?

 

[Valerie Park]

Yes, that is correct. The difference in energy between the front and back face measurements of the first detector is due to the particle passing through the detector and losing energy in the process, which is why the resolution of the first detector is calculated by measuring the width of this peak. This is different than the second detector, which stops the particle completely, allowing the resolution to be calculated using the standard FWHM/centroid.