Liquid Scintillators

[GigaBecquerel]

Hello!

Years ago I bought a set of liquid scintillators and a PMT off eBay, but I still had no luck in identifying what I actually got.
The Scintillators are built like crystals, without any way for the liquid to get in or out, which struck me as odd. I only knew of liquid detectors for high counting efficiency where you dissolve the sample in your scintillator...

I did some mass spectrometry, it turns out that one is some form of perkin elmers ultima gold, but I am not sure if it has any other additives, I had very little time on the ms.
One is labeles "BoTri in EtOH", the only thing that comes to mind is tri(m)ethyl borate, maybe as a neutron scintillator with the ethanol to help dissolve it all?
The third one is just... green. I have no idea what it is, but I assume it's a scintillator that emits in the UV range, mixed with a wavelength shifter.

I've contacted the very nice people at scionix, but they could not help me in identifying what I have as well....
At least they made me aware of this forum ;-)

Do you guys have any idea what I might have here?
They all react weakly to gamma and beta doesn't really penetrate the housing.

Lukas

[Sesselmann]

Lukas,

Those look like an interesting find. Did you test them with a PMT and if so did they give any spectrum?

Here is a reference to a comprehensive list of scintillation materials, maybe the mystery liquids are on there; http://scintillator.lbl.gov

It would be interesting to make some liquid scintillation solution holders like that and experiment with some organic scintillator solutions.

Steven

[Pavel M.]

Interesting scintillators, Lukas!
Although I'm mostly into GS (and my knowledge about neutron counting is rather limited), I think that "BoTri" in this case stands for boron-triazole, but you are right, from what I've read, it's often mixed together with other boron containing compounds (like tri(m)ethyl borate, boron trioxide, triethylborane, etc.) to boost the boron content as much as possible.
It's usually processed into some sort of transparent plastic, borosilicate glass, or gel, but it can also be just dissolved in some organic solvents and used as a liquid scintillator.
That's all I know, but I'm almost certain that someone on this forum will help you find more info about your particular detectors.

-Pavel

[Mike S]

As a newcomer to this pursuit, I have no information to provide, but as a lover of technical mysteries, I thank you for sharing, and look forward to hearing more as you look for answers.

Mike S.

[GigaBecquerel]

Steven,

Back when I tested the detectors I did not have a MCA at my disposal, so I could not test them for spectroscopy.
As far as I know liquid scintillators never give spectroscopic information for gamma, and beta / alpha can't pass the housing, which is why I am so confused about them.
For neutron detection you could do pulse height analysis and look for 2.3 MeV of the ¹⁰B capture, maybe even discriminate some different particles by pulse shape analysis.
But then again, most won't even make it to the scintillator.

Pavel, thank you for your input!
I am a bit confused as to why it would be boron triazole, I've just never heard about that being used for boron loading.
Sadly I don't have access to a mass spectrometer at the moment, so I can't test for either...

I'd love to get my hands on a known, professional liquid scintillator and play around with that, maybe make my own neutron detector with boron or gadolinium loading!

Lukas

[GigaBecquerel]

It's not looking good for boron, I just removed a 500 µl sample from the scintillator and it does not burn with a green flame.
Of course, it might just mean that there's very little boron in there, but then it would not be a good neutron detector...

https://www.youtube.com/watch?v=fEpFCQ5D9PU
The burning scintillator

https://www.youtube.com/watch?v=e1c7efSOusU
Pure ethanol for comparasion

https://www.youtube.com/watch?v=E9_2ppI1-b4
Pure ethanol with a bit of boric acid for comparasion

Lukas