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CHM-12 Neutron Detector with Preamplifier

The GS-Neutron MKII released November 2016 is an easy to use neutron detector with excellent gamma rejection. This challenging product has been under development for some time and we now have an excellent working product.. Our goal was to develop a useful neutron detector from relatively low cost Russian corona tubes (CHM-12 and others). These tubes are famously difficult to work with as they are terribly noisy and the neutron pulse is weak and short, many people have bought these tubes and given up after spending hours trying to get them to work. The new GS-Neutron has a very stable circuit with a completely steady baseline and strong neutron pulse. The detector is completely blind to gamma radiation and is not easily affected by EMF as many other detectors are. 

At around 900 counts per µSv (9000 cpmR) this detector

is 300 times more sensitive than a BTI bubble detector (30 BpmR)

The preamplifier circuit has an adjustable lower limit threshold (LLD) and hysteresis setting to allow for fine tuning of noisy signals. 

The detector comes supplied with one 9V battery, which will power the detector for approximately 50-100 hours.

This detector is best powered by a GS-USB-PRO as it requires only 475-500V.

Connectivity

The GS-Neutron-150 requires an external DC power source to provide 450 to 475 volts DC high voltage, high impedance bias, we suggest our GS-USB-PRO

The signal output from this detector connects directly to the PC Line In port. It does not work well with the Mic port so for computers without a Line In port we recommend using an external USB sound card. 

CHM-12 Tube Specifications

1. Corona discharge Voltage, MIN..................... 450 V
2. Recommended working voltage MAX............ 500 V
3. Relative efficiency (cpm per µSv/hr)..............15.5   cpm per µSv/hr (may vary from tube to tube)
4. Background counts........................................ 12 cph.
5. Working temperature range ......................... -50 to +100 C˚
6. Tube working life, not less than.................... 1500 h.
7. Efficiency to thermal neutrons (nvth)............. ~0.40  (+-0.05)
8. Weight........................................................ 200 gr. (tube only)
9. Dimensions................................................ length 215mm diameter 8.5 mm
    

Preamp and Build

1. Moderator ................................................ Black HDPE
2. Moderator diameter ................................. 90 mm
3. Preamplifier power (battery)..................... 9V 
4. HV Connector ......................................... BNC
5. Signal connector ...................................... 3.5 mm Audio Jack (mono)
6. Output pulse ........................................... 1.7 V 150 µS
7. Overall dimensions ................................. H 320 mm x 90 mm Ø  

Still have questions? .......... Contact us

Important Notes

These detectors are built from old tube stock and the efficiency may vary from tube to tube,

we shall do our best to test that the tubes are working, but we do not offer a calibration guarantee at this time. 

Hobbyists wanting to roll their own tubes, see separate listing for preamplifier board, click here.