Th232 spectrum from today 3hr sample time

[Conor Whyte]

I just recieved 24g of 99.96% analytical grade Thorium dioxide from a chemical supply vendor. On the surface of the vial with a pancake probe ~80-100,000CPM... With a 2.5" plastic scintillation detector nearly 350,000CPM
Yes, so quite active. All safety precautions were taken around this material, especially since this material is in a very fine powder form.

I managed a 3 hour spectrum from a 12g vial today and managed to see a very complete spectrum from all the progeny. Pb212, Tl208, Ac228 and a few interesting peaks related to single escape peak at 511KeV and another Escape peak at 2103.


Please critique my spectrum for issues. This spectrum was gatherthered in theremino and exported to .CSV... From there dumped into Numbers in MacOS Catalina.

SPECTRUM_2020_02_20_13_18_45.png

[Svilen]

Nice post-processing. Is that Bi-212 (727keV) that you didn't label between Tl-208(583keV) and Ac-228(911keV)?

[Conor Whyte]

Nice post-processing. Is that Bi-212 (727keV) that you didn't label between Tl-208(583keV) and Ac-228(911keV)?

Correct -- I totally forgot the Bi212 at 727.3KeV. Great catch. Had I left this long, I'd probably been able to resolve more peaks.

---> I still have a lead castle to build. This is my next project.
Also trying to port Theremino to Linux for ARM/MacOS as well as the new Beqmoni release.

[Go-Figure]

Hi Conor, nice spectrum!

Svilen alreday told you about Bi212 at 727 keV.

I would say the peak you have around 1600 keV looks like Ac228 at 1588.20 keV rather than K40 at 1460 keV.
The first labelled Pb212 peak is at 238.6 rather than 338.3 as the label says, that's a typo I guess.

I also see you have some lower energy peaks. I can't tell the exact energy just by looking at them, but I guess you should have X-rays from Pb212 around 77-80 keV, and possibly another Bi212 peak at 39.86 keV.
Besides, the annihilation peak at 511 keV is reinforced by a Tl208 peak ar 510.77 keV.

Massimo

[Conor Whyte]

Yes again, you are right....

I went back and had another look. I was a bit sloppy when I quickly read the histogram.

I am going to try and convert the .CSV file so that Interspect can use it for post processing. Numbers doesn't give me the ability to finely tune my X-axis for energies.

Lots of Ac228, several Pb212 peaks... a number of peaks missing that show up under Beqmoni after 4-5 hours resolving time.

[Conor Whyte]

Activity for Th232 is 4.04 KBq/gram, or 96.96KBq in 24g -- 2.6uCi total