Mirion PDS 100G, Spectrometric Personal Radiation Detector

Scintillation crystals, PMTs, voltage dividers etc...
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Go-Figure
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Re: Mirion PDS 100G, Spectrometric Personal Radiation Detector

Post by Go-Figure » 20 Aug 2019, 06:32

Janni wrote:
20 Aug 2019, 02:24
Cool, that is really nice that you can convert it in a GN device! And I thought the detector is the expensive special part and not the software...
Would you also help me with mine to do that? I have also answer from my friend and she can give me the software, but seems like the CD is broken. Anyway maybe it is somehow possible to make it running... I don't know what program modules are available on the CD. I will see in two weeks because now I'm on holiday and not at home.

Regarding accuracy I did just a fast check because there was no time before holiday. I have a small uranium mineral that makes 10uSv/h on very reliable automess AD6 and on the PDS it was only 6, so that is the difference. But I can check more and specify better when back home. I can also compare with another PDS or other devices then. Anyway, the most interesting to me on this device is the spectrum and neutron function. :-)

For Fukushima tour the real-Fukushima.com is the official organization if you want to enter in the exclusion zone with official permission. You can also book a private tour I think. I was together with three other people. I am very sure you don't even need to go in the closed zone to make a spectrum. I'm just so curious person and always want to see everything and this is what I found out then, seems like there are also other ways.
If you need anything just send me a PM when you are back home.

As for the accuracy. I don't know the Automess AD6.
Is it this one? https://www.automess.de/Download/Prospekt_6150AD_E.pdf
I don't know if this can be more reliable than the PDS. I read in the datasheet the detector is a GM tube calibrated for Cs137 only while the PDS is a spectroscopic detector with a 9 cc CsI(Tl) crystal, albeit in dose mode he works in three specific energy "windows" (Am241, Cs137 and Co60).

luuk
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Re: Mirion PDS 100G, Spectrometric Personal Radiation Detector

Post by luuk » 20 Aug 2019, 06:39

Hi guys,
Turning on the neutron option does not mean it can measure neutrons!
There are two different detectors for these unit, the first one is just a CsI(Tl) crystals for gamma's, the second one is a combination from two crystals in one detector CsI(Tl/LiL(Eu) that is the only one that can also detect neutrons.
So if your Pds-100 has the second type detector inside than it is useful to turn on the neutron option but it I expect that it would be already done at the factory!
Because there is a big price difference between the two detectors, LiL(Eu) is an expensive scintillator I don't expect you get an pds-100 with that special detector inside without paying extra for it, but who knows you could be lucky.
Luuk

Janni
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Re: Mirion PDS 100G, Spectrometric Personal Radiation Detector

Post by Janni » 20 Aug 2019, 06:58

Thank you very much for your help already! I will contact you after holiday. By the way, very nice report with photos in your other post of this nice historic Italien city (Sorry, forgot the name of it).

It is the Automess that I mean and you are right, it is maybe not really perfect to compare because it is different kind of detector. But it is a very reliable and certificated device for professional use. So it has not so much sensitivity and fast response in the very low range, but in that range of 10 uSv it is definitly accurate. However, I want to specify better and more precise when I am back home and have time and then report here.

I have also my PDS with me on holiday to Kroatia, maybe I find something interesting:-)

Janni
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Re: Mirion PDS 100G, Spectrometric Personal Radiation Detector

Post by Janni » 20 Aug 2019, 07:29

luuk wrote:
20 Aug 2019, 06:39
Hi guys,
Turning on the neutron option does not mean it can measure neutrons!
There are two different detectors for these unit, the first one is just a CsI(Tl) crystals for gamma's, the second one is a combination from two crystals in one detector CsI(Tl/LiL(Eu) that is the only one that can also detect neutrons.
So if your Pds-100 has the second type detector inside than it is useful to turn on the neutron option but it I expect that it would be already done at the factory!
Because there is a big price difference between the two detectors, LiL(Eu) is an expensive scintillator I don't expect you get an pds-100 with that special detector inside without paying extra for it, but who knows you could be lucky.
Luuk
Ok, so it is still not clear... But what is then the neutron counts from Massimo in the Software? I think I will open mine and report what I find inside... or maybe just ask someone from Mirion :-)

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Go-Figure
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Re: Mirion PDS 100G, Spectrometric Personal Radiation Detector

Post by Go-Figure » 20 Aug 2019, 07:43

luuk wrote:
20 Aug 2019, 06:39
Hi guys,
Turning on the neutron option does not mean it can measure neutrons!
There are two different detectors for these unit, the first one is just a CsI(Tl) crystals for gamma's, the second one is a combination from two crystals in one detector CsI(Tl/LiL(Eu) that is the only one that can also detect neutrons.
So if your Pds-100 has the second type detector inside than it is useful to turn on the neutron option but it I expect that it would be already done at the factory!
Because there is a big price difference between the two detectors, LiL(Eu) is an expensive scintillator I don't expect you get an pds-100 with that special detector inside without paying extra for it, but who knows you could be lucky.
Luuk
I hear you luuk.
My information on the matter are the same cicastol has, same hardware, but it might be wrong.
I was in touch with a man from Mirion last month, it took me a long time before finding someone who could actually answer my questions on the device. I can try to get in touch with him again and clarify this matter.
This is the result of a 5 hours data acquisition I did this afternoon in my office (pretty low background), and for the first time the average CPS for neutron showed in the display. 0.15 is pretty low, but it's probably not too far from what you should expect in a "normal" situation. Was it really detecting those neutron? As I said I will try to clarify the matter.
DSC04306-R.jpg
It is the Automess that I mean and you are right, it is maybe not really perfect to compare because it is different kind of detector. But it is a very reliable and certificated device for professional use. So it has not so much sensitivity and fast response in the very low range, but in that range of 10 uSv it is definitly accurate. However, I want to specify better and more precise when I am back home and have time and then report here.
I am bit reluctant in commenting on a detector I don't really know and I've never used before, so I might be very wrong here, but reading is a GM tube calibrated for Cs137 I am not sure it can actually discriminate the different energies of what goes through it with the same precision a spectroscopic detector with a scintillator can.

cicastol
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Re: Mirion PDS 100G, Spectrometric Personal Radiation Detector

Post by cicastol » 21 Aug 2019, 01:59

luuk wrote:
20 Aug 2019, 06:39
Hi guys,
Turning on the neutron option does not mean it can measure neutrons!
There are two different detectors for these unit, the first one is just a CsI(Tl) crystals for gamma's, the second one is a combination from two crystals in one detector CsI(Tl/LiL(Eu) that is the only one that can also detect neutrons.
Hi Luuk, mine is equipped with 22B28/0.75MCSTXN detector , it is the neutron & gamma or only the gamma ? only you can clarify the type of detector !
I think all PDS100G only has this type of detector.

Thanks!
Ciro

cicastol
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Re: Mirion PDS 100G, Spectrometric Personal Radiation Detector

Post by cicastol » 21 Aug 2019, 02:07

Go-Figure wrote:
20 Aug 2019, 07:43
I am bit reluctant in commenting on a detector I don't really know and I've never used before, so I might be very wrong here, but reading is a GM tube calibrated for Cs137 I am not sure it can actually discriminate the different energies of what goes through it with the same precision a spectroscopic detector with a scintillator can.
Hi Massimo,
Automess AD6 has an energy compensated GM tube (ZP1200) with good linear response across wide energy range, it's one o the best device of this type .
Ciro

cicastol
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Re: Mirion PDS 100G, Spectrometric Personal Radiation Detector

Post by cicastol » 21 Aug 2019, 02:27

Janni wrote:
20 Aug 2019, 02:24

Regarding accuracy I did just a fast check because there was no time before holiday. I have a small uranium mineral that makes 10uSv/h on very reliable automess AD6 and on the PDS it was only 6, so that is the difference.
Hi, the problem imho is the source-detector geometry, i think you need to compare in a uniform radiation field , i did a check in a high radiation background near Uraninite mine
(2uSv/h field) and AD6 showed near identical results like PDS100.
Ciro

luuk
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Re: Mirion PDS 100G, Spectrometric Personal Radiation Detector

Post by luuk » 21 Aug 2019, 04:29

If your detector has a 22B28/0.75MCSTXN inside it can only detect gamma's
Luuk

luuk
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Re: Mirion PDS 100G, Spectrometric Personal Radiation Detector

Post by luuk » 21 Aug 2019, 04:33

Hi guys,
As far as I know is the detection from neutrons based on PHD (Pulse Height Discrimation) and not on PSD (Pulse Shape Discrimination).
That means that the detector considers every puls above a certain level to be a neutron.
This principle is used in most portable detector systems, because good PSD analysis is a complicated and very expensive method.
The PHD method is much more simple, it works as follows: every pulse above a fixed level mostly around 3.0 -3.4MeV is considered to be a neutron because the “normal” gamma energy is lower than ± 2.9MeV.
Unfortunately there are high energy cosmics’ that interact with the detector that also give pulses far above the maximum gamma energy and therefore they will be detected as a “neutron”! so it will give you a false "neutron" reading on your detector.
So again I am not certain how the PDS100G works but my guess is it used the PHD to detect neutrons.
Luuk

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