Bicron detector wiring

[luuk]

Hi Svilen

To connect this detector to a GS you need a single connector connection, one wire for high voltage and signal.
It can not be done with the wires that come out of the detector.
You need to be modified the voltage divider inside , this can only be done by opening the back of he detector to get to the voltage divider.

Luuk

[Svilen]

Yes, but I have the GS model with two BNC ports which supports also separated HV bias and signal, can't I use it for this detector without modification then ?

[luuk]

Hi Svilen

I am not familiar with the GS units so I did not know that there is also one with two separated hv and signal connectors.
You can connect your detector as follows:

Black is + HV
Red = ground
Mantel Coax= ground
Centre coax needs a 1nF/1kV capacitor serial is signal (warning on the centre of the coax is high voltage that is why you need a capacitor!!!!!)
The white wire is not used but there is high voltage on it so isolate it properly!

Succes,
Luuk

[Svilen]

Thank you very much Luuk! I'll try it and report back the result.

[Sesselmann]

Luuk,

What were they hoping to achieve with that rather unorthodox wiring of the PMT?

Steven

[luuk]

Hi Steven,

As far as I know it an design (from the customer) and it was made so that it could work on positive or negative high voltage, but as far as I know they only use it on positive high voltage.
The active part around the last dynodes is keeping the pmt stable when there is a high counter rate.
The white wire is used to temporarily reduce the gain when there is a high exposure, it works if you connected with ground the gain reduces around 100x.
But this is only for sure for the Scionix detector for the Bicron I think it is the same but I have never seen a Bicron open to compare it, so no warranty that it works the same.

Regards,
Luuk

[WillemG]

Hi Svelen,
I am also problem solving around Bicron detectors, but in my situation I have preamp directly connected and I am considering not to use preamp and instead, but take anode output direcly to my GS 1100. I have to solder then a new connection to BNC.
From Saint Gobain website you can get a lot of useful info about radiation measurement, data sheets and voltage divider design considerations, see:
www.crystals.saint-gobain.com

and look further at "radiation detection" and "detector operating and service"

From these schemes you can also see that connecting D1 to ground via "white" is not OK and that you better put "housing and coax shield to ground and not connect "white"

Kind regards,
Willem Glasz

[Svilen]

Hello again "radioactive" people,
Thank you for your post Willem!

I connected the detector the way Luuk proposed me, but unfortunately it didn't work. No signal. I got only some noise, when I boost up all the controls of the sound card. I tried with both PRA and Intune. Tried on another computer - same result.

Otherwise the high voltage is there (50V lower indeed, but I guess it's not a problem) and touching the pin of the signal BNC connector makes noise, which I guess proves to some extend, that the amplification circuit of the GS also works. Maybe Steven can say if this is enough or should I test something else on the GS?
Maybe next step is to open it, hoping that the PMT and the crystal are OK, and make the voltage divider which Steven shows here: http://www.gammaspectacular.com/index.p ... t&path=197
What do you think ?

[Sesselmann]

Yes I confirm that tapping the centre pin of the signal BNC should cause a pop in the loud speaker when the GS is working.

So your wiring should be, Black to positive HV (centre pin), Red to ground, on the BNC and voltage set to around 750V.

The white wire should be left disconnected and taped up for safety.

That leaves you with the coaxial signal cable, and as Luuk pointed out there is no coupling built in, so you need something like a 10pF capacitor rated for more than 1000 volts inline between the signal and the GS signal input.

Then with the switch on the GS set to the up position you should get some pulses out from the audio line, so the mono to mono jack plug goes between the GS and your computer line in.

Steven

[Svilen]

I think so Steven, this is how I connected it, with the difference that I used 1nF 3KV capacitor as Luuk adviced in his post.

Luuk said:
"Black is + HV
Red = ground
Mantel Coax= ground
Centre coax needs a 1nF/1kV capacitor serial is signal (warning on the centre of the coax is high voltage that is why you need a capacitor!!!!!)
The white wire is not used but there is high voltage on it so isolate it properly!"

This is what I did:



Is it correct ? If correct, should I try with a 10pf or this doesn't make big difference in this case ?