This post describes how to build a versatile A/B/G ionizing radiation detector for about $200 using the LND 7317 detector tube.
Most Geiger counters are able to detect Beta & Gamma radiation, and perhaps X-rays; these are the more energetic types of ionizing radiation. However, Alpha radiation is the most frequent source of health problems, usually by inhalation in the form of radon gas, and is not easily detected. There are other sources of alpha particles that are more exotic, but still hazardous when ingested or inhaled. Uranium & polonium in granite counter-tops is a common environmental source of Alpha radiation. Detection of radiation in the environment and food-chain is of increasing importance to health and safety.
The key element to detecting Alpha particles is the sensor, or GM Tube. Only sensors with a radiation transparent “window” that allows the Alpha particles to pass-through can be used. This window is usually made of mica. The LND corporation LND-7317 is one such GM tube, and costs about $130. The tube is very sensitive, and also detects Beta & Gamma radiation.
I used “Atomic Dave’s” mounting bracket & installation kit for attaching the LND-7317 ($12.) Read the information in his auction post to acquaint yourself with the issues in dealing with this GM tube.
To cut the hole in the case, I used a Harbor Freight #69063 circle cutter. Be sure to have the enclosure well secured before cutting.
I’m using a Pelican case model 1040 to transport the sensor in a pressure-stabilized fashion. A couple of pieces of DU-BRO 513 1/4″ R/C foam cradles the completed detector snugly:
The rapid change in pressure from the careless slam of a car door could rupture the thin mica membrane (it’s almost 1.5″ in diameter). LND mails the sensors in a small sealed “coffee can”. This isn’t an issue for GM tubes with a small or no mica window. Be careful if you live at a high altitude (see Atomic Dave’s blurb).
The sensor must then be coupled to a high-voltage power supply and detector hardware. DIYGeigerCounter makes “Arduino“-based kits that can be directly wired to the LND-7317 for about $55 (plus enclosure, battery). These kits support many other GM tubes as-well (the SBM-20 is one of my favourites). I’ve built several of the kits of different versions & options. One of them runs 24/7 “internet of things” connected to radmon.org (Colorado Springs, Colorado, USA) using the GKNet module.
Be aware, there are no “safe” limits to ionizing radiation; merely exposures, below which the effects are uncertain. Governments set “safe” limits, but recently have begun to raise these limits arbitrarily in response to environmental disasters. Do your own research and become informed.
Both David @ Atomic Dave’s, and John @ DIYGeigerCounter are great guys, and very helpful. I don’t hesitate for a moment to recommend doing business with either of them.