Search found 27 matches

by Lukas Springer
Tue Jan 28, 2020 12:46 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Easy $150 Neutron Detection System
Replies: 23
Views: 3252

Re: Easy $150 Neutron Detection System

I'm a bit surprised your ludlum managed to detect the events, in my experience the model 3 need a small notification for a lower trigger. Also 750V is not the "Corona mode voltage", but only the ignition voltage, meaning that the detector is in corona discharge *above* that voltage. https://www.yout...
by Lukas Springer
Mon Jul 01, 2019 11:21 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Joe Gayo's lab tour
Replies: 69
Views: 28698

Re: Joe Gayo's lab tour

Damn statistics, ruin everything! :D

That sounds like signal pileup in your detector, have you tried just using a higher distance to your reactor?
faster shaping can do only so much and most gas proportional detectors are not made for high counting rate.
by Lukas Springer
Mon Jul 01, 2019 10:22 am
Forum: Fusor Construction & Operation (& FAQs)
Topic: Joe Gayo's lab tour
Replies: 69
Views: 28698

Re: Joe Gayo's lab tour

Your most recent graph shows some "oscillation" / quantized steps, any Idea as to where this comes from?
by Lukas Springer
Tue May 21, 2019 8:27 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: DIY Charge sensitive Amplifier
Replies: 5
Views: 5255

Re: DIY Charge sensitive Amplifier

The pin does not have to be lifted, with proper guard traces the capacitance can be held at a minimum. Also, this is a CSA, not a voltage amplifier, the input capacitance is not as important, since it only affects pulse shape, not the absolute output. The parasitic leakage and capacitance of the res...
by Lukas Springer
Mon May 20, 2019 10:04 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: DIY Charge sensitive Amplifier
Replies: 5
Views: 5255

Re: DIY Charge sensitive Amplifier

Did some noise measurements, noise is equivalent to 2.5 fC / 115 keV (Si).
Next revision will half that, a smaller feedback cap should also fix this.
by Lukas Springer
Sun May 19, 2019 8:25 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: DIY Charge sensitive Amplifier
Replies: 5
Views: 5255

DIY Charge sensitive Amplifier

Hello! Since my HP 5554A died I was in need of a proper charge sensitive amplifier for my detectors. They're not often on ebay, and if they are it's $100+... So I designed my own: The Operational amplifier is the heart of my design, that's why I choose a very fast one, with very low input current. T...
by Lukas Springer
Wed Mar 20, 2019 9:12 pm
Forum: Images du Jour
Topic: Neutron detector build
Replies: 4
Views: 2490

Re: Neutron detector build

I don't see why you seem to dislike the russian SNM tubes and "my" circuit that much. The circuit with a 100 pF / 16 kOhm high pass filter is recommended by the manufacturer, what else can you wish for. The low impedance filters out pretty much everything of the high impedance corona noise, leaving ...
by Lukas Springer
Thu Feb 28, 2019 9:58 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Collection of information about russian SNM tubes
Replies: 13
Views: 11188

Re: Collection of information about russian SNM tubes

Which just goes to show how easy to use those tubes are :) No window comparator needed, no fine tuning, just a comparator with some hysteresis and done! I've got a question for you, steven: You spec your GS-NEUTRON-150 as 15% efficiency, is that with the moderator in a fast neutron field or just a s...
by Lukas Springer
Wed Feb 27, 2019 10:21 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Collection of information about russian SNM tubes
Replies: 13
Views: 11188

Re: Collection of information about russian SNM tubes

I'm sorry, maybe I'm bad at explaining, but I wanted to make the point that people don't have to be "scared" by those russian detectors, but that they're instead pretty easy to use once one got the hang of it. They reject the 59 keV of Am-241, tested with a source giving off > 3mSv/h at point blank,...
by Lukas Springer
Wed Feb 27, 2019 7:01 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Collection of information about russian SNM tubes
Replies: 13
Views: 11188

Re: Collection of information about russian SNM tubes

There is no corona noise, that is true, but gamma peaks get huge. With some corona current gamma rejection becomes really easy, since all gamma events are drowned out in the noise and only neutron events get above it. Setting your disc to ~1.5 times the voltage of your noise pretty much garantees yo...