*** 50% of the profit from this kit will go toward disaster relief in Japan ***
So why would I build an ion chamber instead of a Geiger counter? Given the recent events in Japan (Let us all hope and pray for the safety of Japan), interest in Geiger counters have gone through the roof. Geiger tubes have all of a sudden become harder to get and the prices for tubes and Geiger counters have gone up considerably. I even hear that they have sold out of Geiger counters in France. The parts to build an ion chamber are cheap and readily available. Also most of the tubes (like the CI-3BG) that I see available on ebay are only sensitive to gamma radiation, some like the SBM20 will detect beta and gamma radiation. While this project will not tell you exactly how much radiation the source has, it will detect gamma and beta sources without any trouble, and if you want to detect alpha sources you can put a sample inside of the chamber. So it will tell you with relative certainty if something is radio active. This ion chamber is so sensitive that it detects the lantern mantles from over 6 inches away, which I was very surprised to see.
Kits contain all of the resistors, trimmer pot, transistors, battery snap, and hookup wire needed to build your own ion chamber.
The kit maker will have to provide a 9V battery, cookie tin or tea tin, aluminum foil, digital multimeter or analog multimeter with a 200-400mV range, soldering iron, and hand tools required to complete the build.
The premium kit includes a 7 function digital multimeter.
See the video of this detector in action (this unit took me less than an hour to build ):
Are you asking yourself how does this detect radiation? Here is a simple description: The ion chamber indirectly detects ionizing radiation by measuring ion pairs created when the radiation passes through the chamber. Radiations such as alpha, beta, gamma, and x-ray are energetic enough to dislodge electrons from atoms and molecules creating ion pairs. One side of each ion pair is positively charged and the other side is negatively charged. In order to detect the ion pairs inside of the can we need a way to collect them. The can body is positively charged to about 9V and forms the anode of the circuit that attracts the negatively charged side of the pair. The probe in the can is attached to the base of a darlington pair transistor and it forms the cathode of the circuit that attracts the positive charged side of the ion pair. As the radiation passes through the chamber, air in the chamber becomes ionized, the more radiation that passes through the chamber results in higher ionization levels. As ions pairs get collected at the anode and cathode it causes current flow in the circuit that is amplified and measured by the meter.
Any ion chamber kit shipped to Japan will be sold for $3.75 each plus postage. For sales to Japan please contact firstname.lastname@example.org