A custom handmade Geiger Counter based on a Russian SBT-11A tube was installed outside to monitor for any radiation changes. A photo of the tube can be seen here:
The tube was purchased on eBay from a seller in Ukraine for around $50.00USD. More information on the SBT-11A can be found here. The tube is sensitive to Alpha, Beta partials and Gamma rays. Since the Geiger Counter is mounted outside with a plastic bag surrounding the device it will not pickup Alpha partials very well since they are blocked by even a thin piece of paper. Here are the tube specifications:
- Voltage of start of counting - 260-320 V
- Operating Current each section (uA) - 0.5-1.1
- Recommended Operating Voltage - 400 V
- Plateau Length/ Inclination - 80V/0.5%/V
- Own Background (Pulses/s) - 0,6
- Length - 55 mm Width - 29 mm
To complete the Geiger Counter a power supply with a microprocessor was purchased through DIYGeigerCounter. The cost was around $55.00USD with the LCD screen. The board uses a ATmega386 Arduino "Uno" compatible CPU that does the event counting and displays the information on a small LCD screen. The firmware on the board was modified to communicate with a C++ program running on our Windows 7 based earthquake datalogger system. The program collects the data from the Geiger Counter once per minute and generates a set of plots that can be seen here. The plotting program gnuplot is used to create the actual gif images from the Geiger Counter data. All of the plots are in Counts Per Minute or CPM and the time axis is in UTC/GMT time.
Here are some pictures of the D.I.Y. Geiger Counter. Not pretty but functional...
