March 2025

Lead 210 – Why Radon is actually not so short lived

Welcome back my fellow radiation nerds! Today we will take a closer look at a radioactive isotope of lead, Lead 210!

Element Lead 208

The element Lead (Pb) is a dense, heavy metal with an atomic number of 82, making it the heaviest stable element in the periodic table. Despite its high density, Lead is surprisingly soft, which makes it easy to bend and shape. In its pure form, Lead has a silvery grey colour, similar to most metals but if it is exposed to air, it will oxidise and darken over time as a layer of lead oxide forms on its surface.

Lead has been known to humanity since the ancient times where it was a popular material thanks to its malleability and relatively low melting point of 327 °C. For example the Romans, used Lead in plumbing, cookware, and cosmetics. However, they weren’t aware of its toxicity which contributed to many health issues including neurological damage, gastrointestinal problems, and developmental delays.

Today the use of lead is much more limited to help minimise potential health risks it poses but it is still being used in some key industries including production of lead acid battles or in radiation shielding.

In nature, there are several isotopes of lead, with the most common being Lead 208, which makes up 52.4%. This is followed by Lead 206 at 24.1% and Lead 207 at 22.1%. All of these isotopes are stable, but lead also has a few naturally occurring radioactive isotopes. These isotopes, are found in the decay chains of Uranium or Thorium, and aren’t present in typical lead ore. Most of them have a pretty short half-lives ranging from a few minutes to several hours—except one: Lead 210.

Radioactive Lead 210

Lead 210 exists naturally in trace amounts as it is one of the daughter isotopes of Uranium, more precisely it is produced by the decay Polonium 214 through an alpha emission or by the beta decay of Thallium 210. It undergoes a beta decay into Bismuth 210 and it also releases a gamma ray at 47 keV and has a half-life of 22.3 years. Bismuth then undergoes a beta decays into Polonium 210 which finally decays into a stable Lead 206 by releasing an alpha particle.

Very rarely Lead 210 will undergo an alpha decay turning into Mercury 206 which then decays through a beta emission into Thallium 206 which finally decays by releasing a beta particle, turning into a stable Lead 206

Since lead 210 is the only Radon daughter isotope with long half-life, it can accumulate and build up over time in areas where high levels of radon gas are present. This is the case with my DP-63-A, which insides are still heavily contaminated with Pb-210 despite the Radium dial being removed long time ago.

My sample

My sample of Lead 210 is a bit of an unconventional one. In order to create it, I used active carbon pallets which I then exposed to a strong radon emitter and I left them sealed in a jar for over two years. After removing the radon source, the jar was highly radioactive due to all the short lived isotopes being present but after a few day, they have decayed leaving only longer lived isotopes including Lead 210 and Polonium 210 inside.

When the lid of the jar is removed, the active carbon pellets reads 500 CPM on my Ludlum Model 3 with a 44-9 probe when measured just above the opened jar. The gamma dose rate is just barely above background and my RAYSID only detects an increase of about 10 CPS when placed right next to the jar.

Gamma spectroscopy

A gamma spectroscopy of my Lead 210 revealed a clear peak at 47keV with a smaller X-ray peak to the left. This peak at 47keV can be also seen in gamma spectra of Uranium or Radium samples which makes it pretty interesting to see how peaks from parent isotopes star to disappear as we go lower in the decay chain.

Gamma spectra made with RAYSID <7% FWHM

Summary

Exploring the radioactivity of Lead 210 was a lot of fun and I certainly learned a lot about it! It definitely showed me that while radon might have a short half-life of only 3.6 days, its daughters will remain radioactive for many years to come.

If you want to find out more about Radon I recommend checking out my previous video on it, which I have linked in the description.

I want ot hear from you! Do you have any Lead 210 samples and what other radioactive isotopes should I cover in the future videos? Let me know in the comments below!

Thank you so much for reading this post, I hope you enjoyed it and learned something new! If yes, please make sure to subscribe to the email list so that you get notified when new posts are added. Also feel free to check out my Ko-Fi page where you can donate a nice cup of radioactive coffee and support my work financially.

and remember, stay active!

By allRadioactive, ago

Bicron 1.12×1.12M3/1.12L Scintillator – How good is this budget scintillator

Welcome back my fellow radiation nerds, Today we will take a closer look at a budget Bicron scintillator probe and whether it is any good.

What’s the deal with this detector?

The detector we will be covering today is the Bicron 1.12×1.12M3/1.12L (P/N I600-2265). What really caught my attention, is that those scintillators can be found for dirt cheap, often way below 100 euros making them one of the most affordable scintillation probes on the market.

Originally they have been designed for use in portal monitors, which is why these detectors have a quirky, cubic design, and the cable awkwardly sticks out to the side. Since I wasn’t a fan of that, I modified my unit by adding a BNC connector at the back. It was a pretty simple mod, and if you decide to do it for yourself, be sure to properly seal back the detector to prevent any light leaks, as they will permanently damage the photomultiplier tube resulting in the failure of the detector.

However what “counts”, is what is inside and that is a 1.12×1.12×3 inch, NaI(Tl) crystal making the probe very sensitive to gamma radiation resulting in background alone being at around 5-10k CPM. The operating voltage should be between 600V and 1000V and personally I’ve been running the scintillator at 650V without any problems and recently started to use it at 900V so that I can quickly swap out between the scintillator and my 44-9 pancake probe and I haven’t had any issues.

The extra sensitivity of the detector came in handy during my recent trip to the military aviation museum in Berlin, where I could easily pick up Radium dials in the airplanes from even a few meters away.

I’ve also took it on my recent Uranium prospecting trip and it performed fantastically being able to detect rocks buried deep underground, which I wouldn’t be able to find with a traditional geiger counter.

One downside of this detector is that it might be sometimes too sensitive. As mentioned before, the background alone is between 5-10k CPM, which makes only the x10 and x100 scale usable on my Ludlum Model 3 and hot rocks like the ones I found during my trip, will quickly max out my meter. So while the detector did a great job at finding hot spots, I did end up using my RAYSID and BetterGeiger S-2 and S-2L for pin pointing the exact location of the rocks. One solution could be to run the scintillator at lower voltage, maybe around 500-550V which will lower its sensitivity and give a bit more headroom.

One interesting thing about many Bicron scintillators is that they have this weird potentiometer sticking out. It is basically a gain adjustment which allows to control how strong the output is. This doesn’t affect sensitivity but can be useful for gamma spectroscopy and slightly improve resolution.

Gamma Spectroscopy and resolution

Speaking of which, this scintillator is definitely a great tool for detecting radiation, but can it be used for gamma spectroscopy? So far I had chance to test 3 of those units with my Gamma Spectacular GS-PRO-V5 and the results varied drastically from being “ok” at 7.8%, to pretty much unusable at over 13% at 662 keV. It really is a gamble with those detectors and if spectroscopy is a priority for you, then I’d definitely recommend getting a higher-end probe for that purpose.

Summary

Overall the Bicron 1.12X1.12M3/1.12L detector is a real bargain and is definitely worth considering if you’re looking for decent scintillator that wont break the bank. It won’t produce amazing gamma spectra but for radiation detection, it performs fantastically!

I want to hear from you, do you have any scintillator probes in your collection? What do you use them for? Let me know, in the comments below!

Thank you so much for reading this post, I hope you enjoyed it and learned something new! If yes, please make sure to subscribe to the email list so that you get notified when new posts are added. Also feel free to check out my Ko-Fi page where you can donate a nice cup of radioactive coffee and support my work financially.

and remember, stay active!

By allRadioactive, ago