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Month: January 2022

Gamma Spectrometer

Gamma Spectrometer

I recently acquired a small gamma spectrometer that I can used for radioactive sample profiling. A simple Geiger counter can detect alpha, beta, and gamma emissions but does not have way to measure the energy level of the detected emissions. A gamma spectrometer can measure the energy of a gamma emission which provides a profile of the sample under test.

As a first test I used a Cesium 137 sample from Oak Ridge. This is a sample I have had since 2011 and used for misc calibration. Cesium decay is a great source since it has a nice mono energetic emission at 662 keV. You can see that emission on the chart, as well as a few other cool things. On the far left you can see an emission at 32 keV that is the result of internal conversion where an electron in the 1s orbital is energized and an an electron from an upper orbital replenished it, releasing the 32keV X-ray.

A second cool effect is the bump at 184keV which is the result of Compton Backscatter. The Compton effect is the result of electromagnetic radiation passing thru and interacting with matter.

I pulled some radioactive samples out from my nuclear archive to test, and I included a couple of them here. I have some excellent Radium-226 samples that are inside radioactive vacuum tubes from the early 1950s. That spectrum shows the Bismuth 214 peak, and a bit of the Radium 226 peak. I also tested a Thorium Ore sample which had the PB-212, Ti208, and Ac228 lines present.

A cool tool to add to my tool chest. One never knows when a radioactive sample might need to be identified!

A bump

A bump

My friend Dan Martin pointed out that if you have local pressure recorders you can see the pressure wave from the Tonga Volcanic explosion. Sure enough just past 4am you can see the jump in the sensor in my shop. Pretty cool to see how it can be detected.

https://www.youtube.com/watch?v=zoMRwyNhqJ4