Depleted Uranium 238
Posted: 04 Apr 2023, 18:22
Hello Forum,
I am writing this post because I have been an enthusiast for 30 years but I am recently entering the world of gamma spectrometry so I would like to share some doubts with you to take advantage of the greater experience of some of you.
Because measuring the radioactive minerals in my collection is still complex given the overlapping of many radioisotopes, I preferred to start analyzing single elements and after CS137, Co60, K40 and TH232 (which I also use for calibration), I switched to a piece of depleted uranium.
Below you will find a spectrum obtained with a 2" CsI probe and Spectacular Spectacular spectrometer, PRA software and a measurement time of about one day (22 million counts) to obtain a nice "smooth" spectrum
What I expect is Uranium U238 with only first children and a small percentage of U235 and first children (U235 in % lower than which would be found with natural uranium, being depleted).
I have doubts about a couple of peaks so I would like to share the results with you. I also used Interspec to help identify.
U238 inserted in self-made shielded case with Pb (6cm), Cu (8mm), Al (2mm), Plastic (1mm)
Peaks:
A = here I have a doubt as the peak falls halfway between two possible main emissions, one of U238 and one of U235 as can be seen from the Interspec low energy image. Both are "probable", the first, for U238, Pa234m>U234 at 43.5 KeV while the second, for U235, Th231>Pa231 at 25.65KeV. It is obvious that here I should have better calibrated the probe using maybe the 32kev line of the Cs137 and perhaps the peak would have fallen more precisely. But anyhow… What do you think?? The peak is at 32.33 KeV but probably miscalibrated
B = Th234>Pa234m at 63.29 KeV (U238 series)
C = U238>Th234 at 92.38 and 92.8 KeV (U238 series)
D = here I don't know ! Interspec tells me that in this position there should be U235>Th231 and Th234>Pa234m but they are really insignificant as probabilities while here the peak is high. The peak is at 107-108 KeV. Even with uranium ore or various sources, I always get this peak but can't identify it.
E = peaks at 143 and 163 KeV of U235 (in uranium glass having more U235 they are seen distinct and evident, therefore they are "weak")
F = U235>Th231 at 185.71 KeV (U235 series)
G = a slight “hump” is seen around 255 KeV. Is it Pa234m>U234 at 258.26 KeV( U238 series) ??
H = correct to say that it is Pa234m>U234 at 766.37 KeV (U238 series)?
I = correct to say that it is Pa234m>U234 at 1000.99 KeV (U238 series)?
Thanks in advance
Marco
I am writing this post because I have been an enthusiast for 30 years but I am recently entering the world of gamma spectrometry so I would like to share some doubts with you to take advantage of the greater experience of some of you.
Because measuring the radioactive minerals in my collection is still complex given the overlapping of many radioisotopes, I preferred to start analyzing single elements and after CS137, Co60, K40 and TH232 (which I also use for calibration), I switched to a piece of depleted uranium.
Below you will find a spectrum obtained with a 2" CsI probe and Spectacular Spectacular spectrometer, PRA software and a measurement time of about one day (22 million counts) to obtain a nice "smooth" spectrum
What I expect is Uranium U238 with only first children and a small percentage of U235 and first children (U235 in % lower than which would be found with natural uranium, being depleted).
I have doubts about a couple of peaks so I would like to share the results with you. I also used Interspec to help identify.
U238 inserted in self-made shielded case with Pb (6cm), Cu (8mm), Al (2mm), Plastic (1mm)
Peaks:
A = here I have a doubt as the peak falls halfway between two possible main emissions, one of U238 and one of U235 as can be seen from the Interspec low energy image. Both are "probable", the first, for U238, Pa234m>U234 at 43.5 KeV while the second, for U235, Th231>Pa231 at 25.65KeV. It is obvious that here I should have better calibrated the probe using maybe the 32kev line of the Cs137 and perhaps the peak would have fallen more precisely. But anyhow… What do you think?? The peak is at 32.33 KeV but probably miscalibrated
B = Th234>Pa234m at 63.29 KeV (U238 series)
C = U238>Th234 at 92.38 and 92.8 KeV (U238 series)
D = here I don't know ! Interspec tells me that in this position there should be U235>Th231 and Th234>Pa234m but they are really insignificant as probabilities while here the peak is high. The peak is at 107-108 KeV. Even with uranium ore or various sources, I always get this peak but can't identify it.
E = peaks at 143 and 163 KeV of U235 (in uranium glass having more U235 they are seen distinct and evident, therefore they are "weak")
F = U235>Th231 at 185.71 KeV (U235 series)
G = a slight “hump” is seen around 255 KeV. Is it Pa234m>U234 at 258.26 KeV( U238 series) ??
H = correct to say that it is Pa234m>U234 at 766.37 KeV (U238 series)?
I = correct to say that it is Pa234m>U234 at 1000.99 KeV (U238 series)?
Thanks in advance
Marco