Energy Resolution of a solid state X-Ray detector

[garyd]

Homework Statement

Hi all,
I have been given the task of quantifying the energy resolution of a p-i-n semi-conductor x-ray detector and present it as a value in electron volts

Homework Equations

%Resolution=E FWHM / Ei
Where E FWHM is the full width half maximum of a peak and Ei is the centroid value of that peak[/B]

The Attempt at a Solution

I can calculate % Resolution no problem, but I need to relate it to an energy value. My detector is connected to a multi-channel analyzer that has 4000 channels. Say I have a calculated a %Resolution of 6% for a certain peak value. 6% of 4000 channels =240. I'm not sure where to go from here. The x-ray unit has an anode voltage of 35keV.
Any help would be appreciated

 

[garyd]

Still working on this and now I'm wondering if my detector energy resolution is the fraction of full width half max of the centroid value? I should also state that I have obtained a counts Vs. energy spectrum of the characteristic x-rays from a copper sample. I have identified the K-α line and applied a normal distribution curve to the data. I have obtained the mean value, i.e. the centroid value and have also determined the full width half maximum energy value. The centroid value obtained for Cu K-α line =8.04 keV and FWHM=0.49 keV. So energy resolution of my detector for this energy is 490keV?

 

[mfb]

If your resolution is 6% of the energy of the specific peak, then you need the energy corresponding to this peak to get the absolute resolution.

The centroid value obtained for Cu K-α line =8.04 keV and FWHM=0.49 keV. So energy resolution of my detector for this energy is 490keV?

Sounds good. Try to verify this with other peaks, if possible.

 

[garyd]

If your resolution is 6% of the energy of the specific peak, then you need the energy corresponding to this peak to get the absolute resolution.Sounds good. Try to verify this with other peaks, if possible.

I have verified the results for five different samples and the numbers look good, So am I correct in thinking that at this energy my detector can not distinguish two peaks that are separated by 490 eV

 

[mfb]

Not on an event-by-event basis, but if you have many events you can see where the average is for a single peak - or you can see the source is not a single peak, and identify the magnitude of both peaks separately.