Thursday, 26 March 2015

Project: New Alpha, Beta & Gamma Geiger Tube SBT-11A

So with all the geiger counters and stuff i have here i realised i had no means to measure alpha particle radiation.

Detecting Alpha particles requires a Geiger Muller tube with a mica window, the mica window allows the retention of the gasses inside the geiger tube but also allow alpha particles to enter and create a count. Using metal or glass for the body of the tube prevents any alpha particles from entering the geiger tube and as such will only be Beta and Gamma sensitive.

After a little searching on ebay i found a seller in Ukraine selling new-old-stock of the SBT-11A tube, it's a flat rectangular shaped tube. It's sensitive to Alpha, Beta and Gamma and operates at around 320v. SBT-11A was ordered from any-devices.

A small metal project box by Hammond was used to house the tube to which i attached a monopod 'selfie stick'.

Total cost to build was about £50.

Hammond 27969P Metal Box

Fitting of the BNC connector.

Fitting the SBT-11A Tube

Connecting to the BNC. The SBT-11A has five connections, two are ground the other three pins are the anodes. There are actually four in this tube, the centre of the three pins connects to anodes 2 & 3. The outer two connect to anodes 1 and 4. So these should be connected in parallel.

Fitting a Tripod screw thread to the box and attaching the angled head from a selfie stick.

Attaching the selfie stick. This is a cheap Chinese stick from Ebay, it's telescopic and can extend to about 1 meter.

Testing the new probe on the Ludlum Model 3