Search found 93 matches

by ChristofferBraestrup
Tue Apr 13, 2021 6:53 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Is a PMT a PMT ?
Replies: 8
Views: 200

Re: Is a PMT a PMT ?

Mu-metal is not yet installed, this is a bare tube.

All mu metal I've ever owned has been pillaged from scrapped CRT's. But Ebay probably has all you need.
by ChristofferBraestrup
Mon Apr 12, 2021 11:06 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Is a PMT a PMT ?
Replies: 8
Views: 200

Re: Is a PMT a PMT ?

You're in for the slightly soul crushing experience of making a really beautiful looking instrument and then completely destroying its aesthetics by flooding it with black tape!

I've just been there!
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by ChristofferBraestrup
Mon Apr 12, 2021 1:45 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Is a PMT a PMT ?
Replies: 8
Views: 200

Re: Is a PMT a PMT ?

This looks like a buck standard bialkali pmt. I suspect it will do just fine. As long as the spectral response isnt wierd. Scintillation counting is a very forgiving setup, pmt wise. The only admitted light is the scintillation light (if you light proof properly!), and they're operated at positive h...
by ChristofferBraestrup
Wed Apr 07, 2021 2:43 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Channeltron woes
Replies: 18
Views: 1234

Re: Channeltron woes

Oh I'm sure you're right, and I'm very grateful for the help! I will try adding in the preamp and see if there is a difference. Perhaps the 3.6n is too large a coupling cap as well. The wrong polarity of my pulses could be my scope being too slow to see the original negative component, leaving only ...
by ChristofferBraestrup
Tue Apr 06, 2021 2:48 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Channeltron woes
Replies: 18
Views: 1234

Re: Channeltron woes

I don't think that's right. There's no voltage drop over the anode resistor, it's purely a current limiting thing. One can also ground it, and take the inverted signal from the last dynode. http://winspa.de/help101/images/Channeltron.jpg http://winspa.de/help101/hardware.htm Here's an example of a b...
by ChristofferBraestrup
Mon Apr 05, 2021 7:49 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Channeltron woes
Replies: 18
Views: 1234

Re: Channeltron woes

For bias a meg seems pretty standard for electron multipliers, but I could be mistaken. Here's an article featuring a neg bias VEU-6 for positive ion detection, and to me it looks like they terminate the output directly in 50 ohm, and get 100-200 mV pulses out. http://www.mathnet.ru/links/da376d7812...
by ChristofferBraestrup
Mon Apr 05, 2021 1:31 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Channeltron woes
Replies: 18
Views: 1234

Re: Channeltron woes

I just realized something strange is going on - Why are my output pulses positive?! I've set up the channeltron for negative ions/electrons, and with signal tapped from the anode. See below for an actual schematic of my setup. If electrons collect on the anode, then the bias should momentarily drop,...
by ChristofferBraestrup
Sun Apr 04, 2021 10:45 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: NIM - "Oh let me count the ways"...but how many ways??
Replies: 6
Views: 546

Re: NIM - "Oh let me count the ways"...but how many ways??

That's more or less exactly the dekatron scaler I was thinking of! Yeah, having one of those in a NIM bin world fill the entire bin! I think fundamentally, if displays and readouts were needed as human friendly readouts, they were important enough instruments that they would have their own rack unit...
by ChristofferBraestrup
Sun Apr 04, 2021 4:56 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: NIM - "Oh let me count the ways"...but how many ways??
Replies: 6
Views: 546

Re: NIM - "Oh let me count the ways"...but how many ways??

These strange scaler displays are really a treasure of display technology - and a horror from a human interface device point of view! The earliest scalers from the 1940s used the cyclic dekatron tubes, which are also bizzarely beautiful. Even into the standardization of 7segment LED displays, the hu...
by ChristofferBraestrup
Sat Apr 03, 2021 9:10 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Channeltron woes
Replies: 18
Views: 1234

Re: Channeltron woes

Oh and some imagery
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