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In this instructable I will be demonstrating how to build a pocket radiation detector or "PIRD." The parts for this radiation detector will all be salvaged (that means no pricey GM tube off of ebay), but building will require steady hands and alot of patience! This is a "clicking" radiation detector, unlike many other DIY versions without a Gieger-Muller tube out there, and I have yet to see anyone try this concept and/or make one like it. Although it may not be as sensitive or practical as a standard geiger counter, it does detect background radiation (most likely gamma rays). Similar concepts are seen on the CERN website, demonstrating the potential to detect both alpha rays and background radiation: (http://teachers.web.cern.ch/teachers/archiv/hst2000/teaching/expt/new/new.htm) and on youtube (http://www.youtube.com/watch?v=RzglpP3D2tQ).
Here is a video testing it using a small amount of radioactive Americium found in a smoke detector:
In this instructable I will be demonstrating how to build a pocket radiation detector or "PIRD." The parts for this radiation detector will all be salvaged (that means no pricey GM tube off of ebay), but building will require steady hands and alot of patience! This is a "clicking" radiation detector, unlike many other DIY versions without a Gieger-Muller tube out there, and I have yet to see anyone try this concept and/or make one like it. Although it may not be as sensitive or practical as a standard geiger counter, it does detect background radiation (most likely gamma rays). Similar concepts are seen on the CERN website, demonstrating the potential to detect both alpha rays and background radiation: (http://teachers.web.cern.ch/teachers/archiv/hst2000/teaching/expt/new/new.htm) and on youtube (http://www.youtube.com/watch?v=RzglpP3D2tQ).
Here is a video testing it using a small amount of radioactive Americium found in a smoke detector:
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Signing UpStep 1: How it Works
This geiger counter works on similar principles that any other ordinary geiger counter works on. Essentially there is a small gap between two wires - a high dc voltage is applied to both wires, and when an ionizing particle moves between the wires, an ion channel is created and electrons arc across the wires, creating an audible "click" on a radio. Normally, the gap is inside of what is called a "geiger muller tube," where gases ideal for ionization are held for increased sensitivity. With this geiger counter, the absence of gases ideal to ionization is made up for by placing the wires in closer proximity to one another (so close that to the human eye they appear to be touching). The process of slowly moving the wires closer to one another is called "spark gap quenching".
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kinda like a ~||_||~ u shaped bracket with the screws from either side.
then you could pretty simply just twist in one of the bolts till it "auto quenched"
sand the tips of the srews to remove any burrs... DONE.
I had a bit of trouble following the pictures and descriptions -- you might consider using the "image notes" to identify exactly where in each picture we should focus.
One comment about your "ambient air" G-M counter. You note that when properly aligned, the counter should discharge every minute or two. That's consistent with sea-level cosmic ray rates in the Northern Hemisphere. I wonder if you could get a more quantitative calibration using an Am-241 source scavenged from a smoke detector?
http://www.youtube.com/watch?v=RzglpP3D2tQ
On an earlier build we thought if 3V gets us 200, then 8v might get use 500 or so, but it seemed to "kill" the unit. Back to the store for a new camera.
Any ideas on what we are doing wrong. We are nowhere close to the 400-600 volts needed to allow the ionization.
Thinking on from that, using a variable HV supply and the flash tube from the camera may make a more stable version as the gas is fully contained. Commercial GM tubes use a variety of noble gases, of which the xenon in the tube is one.