Thoriated glass lenses—sometimes used in vintage cameras to reduce chromatic aberration—may contain up to 30% Th-232 by mass. For this analysis of Th-232, the Radiacode will rely on gamma emissions from its decay products, with a focus on the 238.6 keV peak produced by Pb-212, as well as the 583 keV and 2614 keV peaks produced by Tl-208.
Steps for Calibration:
1. Power on the Radiacode device.
2. Open the Radiacode application on your mobile device and connect to the Radiacode.
3. Turn off the sound to avoid triggering alarms.
4. Place the thoriated glass specimen over the trifoil symbol or beneath the plus sign located at the end of the Radiacode.
5. Reset the spectrum on the application by touching the three dots on the right side of the spectrum and selecting “Restart Accumulation.”
6. Allow the Radiacode device to collect sufficient data. Data collection is complete when the spectrum graph appears filled in with yellow past the 2614 keV line. This should take at least five hours with a thoriated glass specimen measuring 6000 CPM on the Radiacode 103.
7. Once enough data is collected, save the spectrum by pressing the three dots on the right side of the spectrum and selecting “Save Spectrum to Library.” Then, touch the three dots again and select “Energy Scale Calibration.” A blue overlay will appear at the top.
8. Indicate the first peak (point one) on the graph near 238.6 keV by touching it.
9. Enter the value 239 and touch “Next.”
10. Indicate the second peak for point two near 583 keV by touching it.
11. Enter the value 583 and touch “Next.”
12. Indicate the third peak and enter the value 2614, then touch “Finish.”
13. Touch “Save Coefficients” and then “Program Coefficients into Device.”
14. The calibration is now complete.