Russian corona counters get new life
Posted: Tue Nov 24, 2015 7:19 am
Like many of you here on the forum I invested in some Russian neutron detectors, but like most of you I also found out that they were pretty hopeless, they had a noisy signal and a poor pulse which hardly made it above the nose. To be honest i gave up on the project several times, but every now and then when I had some time to spare I gave it another go. Eventually, thanks do David Housley for suggesting a Schmidt trigger it all came together.
This is just one of many different kinds for sale on eBay and from Sovtubes.com
The raw signal from the detector is hopelessly noisy, it's all over the place and you have to wait forever to catch a pulse, sometimes 10 minutes between pulses when you don't have a source.
I designed a simple preamplifier (with some help from David Housley...thanks) it has an adjustable LLD and hysteresis, so it can be used on different tube types. The detector is completely blind to gamma and not sensitive to EMF, I usually test for EMF by turning the fluorescent lamps in my workroom on and off.
The circuit board has 25 turn Bourns trimmer potentiometers for the threshold and the hysteresis adjustments.
The input power for the SNM-12 detector (500V) can be provided by one of my GS-1100A or GS-1100-PRO but can also be provided by any NIM power supply. The output signal is at line level and can be plugged straight into a PC Line In and be analysed by PRA or any of the other open source programs.
I took the detector in to Marek at the University of Sydney, where they have a 2.2 x 10^6 AmBe neutron source, and we were getting 50 cps at 23 cm distance from the source, which after allowing for some paraffin blocks and lead worked out to a detector efficiency of 15% (nvth).
These Russian tubes are quite old and I imagine their efficiency not may be quite what they were 30 years ago, but they would certainly be useful in a fusor lab.
I have a stack of these tubes so if anyone is interested please PM me, or post a reply. For those of you who own Russian corona tubes I am happy to sell the boards only.
Steven
The moderator is manufactured from black HDPE and measures 90 mm Ø, and the whole detector stands about 340 mm tall.
A green LED indicates that the power to the preamp is switched on. The HV connector is an SHV and the signal connector is a standard BNC connector, best to have two different kinds of connectors, as connecting the HV to the signal would certainly kill the detector.
The battery is held neatly in the base of the detector, in the tests I have done so far, the battery life is around 50 hours (2-3 days).
This is just one of many different kinds for sale on eBay and from Sovtubes.com
The raw signal from the detector is hopelessly noisy, it's all over the place and you have to wait forever to catch a pulse, sometimes 10 minutes between pulses when you don't have a source.
I designed a simple preamplifier (with some help from David Housley...thanks) it has an adjustable LLD and hysteresis, so it can be used on different tube types. The detector is completely blind to gamma and not sensitive to EMF, I usually test for EMF by turning the fluorescent lamps in my workroom on and off.
The circuit board has 25 turn Bourns trimmer potentiometers for the threshold and the hysteresis adjustments.
The input power for the SNM-12 detector (500V) can be provided by one of my GS-1100A or GS-1100-PRO but can also be provided by any NIM power supply. The output signal is at line level and can be plugged straight into a PC Line In and be analysed by PRA or any of the other open source programs.
I took the detector in to Marek at the University of Sydney, where they have a 2.2 x 10^6 AmBe neutron source, and we were getting 50 cps at 23 cm distance from the source, which after allowing for some paraffin blocks and lead worked out to a detector efficiency of 15% (nvth).
These Russian tubes are quite old and I imagine their efficiency not may be quite what they were 30 years ago, but they would certainly be useful in a fusor lab.
I have a stack of these tubes so if anyone is interested please PM me, or post a reply. For those of you who own Russian corona tubes I am happy to sell the boards only.
Steven
The moderator is manufactured from black HDPE and measures 90 mm Ø, and the whole detector stands about 340 mm tall.
A green LED indicates that the power to the preamp is switched on. The HV connector is an SHV and the signal connector is a standard BNC connector, best to have two different kinds of connectors, as connecting the HV to the signal would certainly kill the detector.
The battery is held neatly in the base of the detector, in the tests I have done so far, the battery life is around 50 hours (2-3 days).