Alpha Spectroscopy: Why does Peak Resolution Change?

In summary, the conversation discusses a change in peak resolution in an alpha spectroscopy experiment. The distance between the source and detector was increased, resulting in a decrease in FWHM and an increase in peak resolution. The reason for this change is unclear, but it could be due to energy degradation of the alpha particles as they travel through air. The plot shown in the experiment is not fully understood, and there are questions about defining resolution and multiple points at the same distance. Further measurements may need to be done to determine why the peak gets narrower with increased distance.
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I'm trying to understand why peak resolution changed in my alpha spectroscopy experiment.

I've increased the distance between a Am-241 source and a silicon surface barrier (semiconductor) detector and taken spectra along the way, recording information about peak height and FWHM.

As the distance between the source and detector increased the FWHM got lower, but the peak resolution increased. I've calculated the peak resolution = (1/FWHM) * 100 and expressed it as a percentage.

The peak resolution has changed because the FWHM has changed. I understand that much. I don't really understand why the FWHM would decrease though. Is it purely because of the energy degradation of the alpha particles as they travel through air?

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I don't understand what this plot shows. Couldn't you define the resolution as the uncertainty/standard deviation [itex]\sigma[/itex] or FWHM (they both are related if you fit gaussians) of what you measure over the average value? And why do you have several points at the same distance?
If the above can be explained, why did you stop at that point? probably you would have to remake that measurement because something went wrong at that point?
Your explanation (eg alpha energy degradation) wouldn't explain why your peak gets narrower (decreased FWHM)? What you show (as you define your resolution) says that the further away you get, the best your detector records the particles. How do the actual distributions (the ones you used for the FWHM calculation) look like in the small-distance vs those bad ones in large-distance case?
 
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1. What is alpha spectroscopy?

Alpha spectroscopy is a technique used in analytical chemistry to identify and measure the concentration of alpha particles in a sample. Alpha particles are charged particles that are emitted by some radioactive materials.

2. How does alpha spectroscopy work?

In alpha spectroscopy, a sample is bombarded with alpha particles, and the resulting energy spectrum is analyzed to determine the types and concentrations of radioactive elements present. This is achieved by measuring the energies and intensities of the various alpha particle peaks in the spectrum.

3. Why does peak resolution change in alpha spectroscopy?

Peak resolution in alpha spectroscopy can change due to a number of factors, such as the presence of interfering elements in the sample, variations in instrument settings, or changes in the sample itself over time. These factors can affect the ability to accurately distinguish and measure individual peaks in the energy spectrum.

4. How can peak resolution be improved in alpha spectroscopy?

Peak resolution in alpha spectroscopy can be improved by carefully selecting sample preparation methods and using appropriate calibration standards. It is also important to regularly calibrate and maintain the instrument and to carefully analyze and interpret the resulting energy spectrum.

5. What are the applications of alpha spectroscopy?

Alpha spectroscopy has a wide range of applications, including environmental monitoring, nuclear forensics, and medical diagnostics. It is also commonly used in nuclear power plants to monitor the levels of radioactive material in the surrounding environment.

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