Whats Hot and Whats Not – Becoming an Expert With Your Geiger Counter – Spark Detector
Lucaswhitefieldhixson.com
May 30th, 2011
We are at a nuclear tipping point. More people are aware of radiation today, then ever before. There are also more unanswered questions, and many people are looking for qualified experts to explain a complicated field.
I recently came across one of the most interesting DIY videos I’ve ever seen. Carl (Thallium208 on Youtube) has uploaded videos of his home-built Spark Detector, which detects alpha radiation.
Carl has also been to the Ukraine and visited Chernobyl, and Pripyat. I got in contact with him to talk about radiation detection, and the interesting things that a geiger counter owner can find.
After the nuclear disaster at Fukushima Daiichi Nuclear Power Plant, geiger counter sales around the world immediately picked up. Many suppliers are now scouring for manufacturers that are able to keep up with the demand. When a person motivated to a “buying decision”, they also expect to see results.
Radiation is a tricky thing to measure, and its extremely hard to detect, you can’t see, smell, or touch airborne radiation. If a purchaser doesn’t see the results they expect, they can potentially “tune out” to radiation danger in the future.
However, you can’t just buy a geiger counter, and go outside and start taking specialized readings. Radiation is measured in a variety of different ways, and different devices and equations are used to measure the radiation and its potential risk.
To start with, every geiger counter owner needs practice with their device. Different radiation sources will register differently on a geiger counter, and only through experience can you begin to firmly understand your tool.
My interview with Carl – A Radiation Detection Expert
What can you tell me about Carl? I’ve seen some really great videos of you exploring Chernobyl, and Pripyat?
Well, as far as personal details go, I was born into science–to a geologist mother and a physicist father in Oak Ridge, Tennessee (home of the famous Manhattan Project-era national laboratory). And with that background revealed, my life trajectory since has been probably not surprising at all! I majored in chemistry and physics in college and got my MS in nuclear engineering at Ohio State University in 2005.
Since then I have been “working” on my Ph. D. dissertation on accelerator-based neutron sources for a type of cancer treatment, but to be honest I have been mostly working professionally–at Linac Systems, LLC, a particle accelerator manufacturer in Albuquerque, New Mexico; and at Qynergy Corporation, a small research firm that is involved with nuclear batteries, neutron generators, and other technologies of interest to me.
The videos from Chernobyl are from a trip last year, the highlight of which was actually touring the nuclear power station. I’m a “nukehead”: an avocational enthusiast for all things radioactive, including radioactive places, radioactive items, and radiation-related technology of all kinds.
Can you tell me a little bit about your spark detector, and what makes it so cool to look at?
The spark detector is particularly cool to look at because it demonstrates a large-scale, easily-observable phenomenon (in essence miniature lightning) being triggered by the invisible and microscopic processes from alpha radiation passing through the air.
It’s a particularly transparent window into an otherwise-invisible world. You can see the spatially-resolved distribution of the radiation; if you move the source, the sparks follow. This detector has the added advantage of being stunningly simple to create.
It’s the kind of thing my physics adviser at college would have labeled “cute.”
Check out these pictures provided by Carl
What are some different types of radiation detectors you are familiar with, and what do they detect?
I am intimately familiar with a broad range of detection equipment. I own and operate numerous types of scintillation detectors, which detect mostly gamma radiation by the glow it causes in a crystal. I have a high-purity germanium detector for gamma spectrometry. I have ion chambers, Geiger counters, proportional tubes, bubble dosimeters for neutron detection, and a few smaller (than the HPGe, anyway) semiconductor detectors.
This list of equipment encompasses technologies that are exceedingly simple and accessible (Geiger counters), and some that are very costly and obscure.
A lot of my personal interest deals with neutrons and gamma rays, so most of my best equipment is exclusive to detecting one or the other of those. Geiger counters detect alpha and gamma radiation, and often alpha radiation also. I use Geiger counters or scintillation detectors to locate radioactive items in nature or in flea markets.
What do you think about all of the public exposure to new information about radiation they might not have known before?
The Fukushima accident is the reason for a recent renewal of public interest in radiological subjects. The accident is unfortunate, but it is also clearly an opportunity of which people are availing themselves to take interest in and learn about radiation phenomena. It goes without saying that more understanding is a good thing.
Some younger people newly awakened to the relevance of nuclear accidents, radiation metrology, radiobiology, etc. will study these subjects in academia, become experts, and go on to solve problems and make discoveries. Hopefully at the level of the general public, awareness and understanding will prevail as well, in contrast to the high levels of hysteria and phobia that have historically been associated with all things “nuclear.”
So lets talk about all the new owners of radiation detection equipment – Why do I need practice with my geiger counter?
The Geiger counter (or other type of survey instrument) endows its operator with a new sensory dimension. Imagine being deaf and mute, then wake up one day being able to hear. Will you understand what you’re hearing, what people are saying? Probably not.
So you need to get familiar with your Geiger counter and how it responds to radiation, and you need to simultaneously build awareness of the natural and manmade radiation environment around you. Many people who are uninitiated recoil in shock when they turn on their Geiger counter and find it immediately clicking away from everyday background radiation.
Some people worried about fallout from Fukushima have been horrified that rainy weather brings increased activity to their counters at ground level, unaware that natural radon is routinely responsible for essentially all of the observed effect.
To make sense of a Geiger counter’s signal, you have to have some hands-on experience, and the more experience you have, the better you’ll understand the counter.
What do the numbers mean on my Geiger counter and what should be cause for concern?
It is true that higher count rates signify higher levels of radiation. But I encourage you to pay NO ATTENTION to the actual numbers indicated on the scale of any Geiger counter, unless those numbers are counts per some unit of time (CPM, CPS) AND you are comparing your Geiger counter’s reading to an identical unit’s reading (a common example in the US for which CPM counts are widely compared is the CDV-700 civil defense counter).
If you have units of effective dose equivalent (rem, millirem, sieverts, millisieverts) or exposure (roentgen, milliroentgen), note that the meter reading is absolutely meaningless in 99% of the situations in which you’ll encounter radiation with the Geiger counter. The number is only even approximately (+/- 50%) accurate under some fairly strictly-defined and atypical conditions, usually pure gamma radiation fields with energies between ~200 keV and ~3 MeV.
I will defer to the Glenn Knoll book mentioned above to elucidate the physical meaning of these units. The other aspect of reporting quantitative results from a Geiger counter measurement is good statistics. Basic counting statistics are discussed very nicely in the Glenn Knoll book also.
The bottom line is that all measurements should be represented along with the measurement uncertainty. Beginners with Geiger counters should be wary of the significant challenges when attempting to make quantitative measurements with Geiger counters. They can’t be treated like black boxes that spit out a number.
How can I become an expert with my geiger counter?
In addition to playing around with the counter and getting experience finding radioactivity, you should consider joining a community of people that collectively has good subject matter knowledge, and should consider reading a good reference textbook on radiation metrology.
For the former, I recommend “Geiger Counter Enthusiasts” and “The CDV-700 Club” on Yahoo. The BEST textbook in this field, hands down, is Glenn Knoll’s “Radiation Detection and Measurement.” This was my text in a radiation detection course early on in grad school.
It’s understandable to a novice, but packed with enough unobtrusive detail and citations that I keep coming back to it all the time.
So let’s go use a geiger counter – Where can I find radiation in my home?
It’s usually pretty easy to track down your first “hits” with a Geiger counter right in your home. Household smoke detectors typically contain a small quantity of a synthetic (i.e. made in a reactor) alpha- and gamma-emitting element called americium, the Am-241 isotope in particular.
Dryer lint traps and furnace air filters often become quite radioactive during use (and for about half an hour after use) owing to atmospheric radon and its daughters precipitating on the filter.
Radon concentration in the air varies enormously according to the local geology, with granitic or certain shale formations being responsible for the highest activities. As I mentioned earlier, rain
may temporarily increase the activities of radon near the ground.
Consumer products containing concentrated potassium are weakly radioactive and not too hard to detect with most Geiger counters. This includes stump removers (potassium nitrate), some brands of de-icing salt (potassium chloride), salt substitutes (NoSalt, NuSalt,etc.; also potassium chloride), and some varieties of fertilizer.
Lots of people may find that they own some detectably-radioactive rocks (varieties of granites, pegmatites, petrified wood) or gemstones (apatite, zircon, ekanite) that register a count above background.
Some types of glass (vaseline glass) and ceramic pottery (Fiestaware and other “California-style” glazed pottery) are notoriously radioactive due to the presence of uranium. Older mantles for gas lanterns may contain radioactive thorium.
For the real enthusiasts about radioactive consumer items, militaria, minerals, and so on, I recommend the wonderful (though hardly exhaustive) book put together by Bill Kolb and Paul Frame entitled, “Living with Radiation: the First Hundred Years.”
Ok, I’m ready to leave the house – Where can I look for radiation in my environment?
Radon and cosmic rays are usually the culprits whenever your Geiger counter clicks. But if you take your Geiger counter out hiking or biking, you’re likely to eventually come across rock formations that generate counts, and may experience the rise in counts that relates to elevation (cosmic rays are more potent at higher elevations).
It can be difficult to pin down the exact source of radiation if a geological formation is responsible; you’ll just note that the needle reliably swings up to three or four times the usual rate over a period of the trail, then settles back down.
Uranium mines are a different story. If you visit areas that have historically been mined for or that have notable deposits of uranium, such as Arches and Zion National Parks in Utah, you can expect to encounter very high readings on the counter and possibly even find discrete pieces of the active minerals.
Nobody living in the United States is likely to encounter detectable radiation in the environment from man-made sources unless they try really hard (I can name a few examples, though). Other parts of the world are more contaminated. The Techa River in Russia is notoriously radioactive due to operations at the Mayak fuel processing plant near Yekaterinburg, and in Ukraine and Belarus have their respective Chernobyl exclusion zones. Geiger counters will get very noisy in these places.Are there any other places to take a geiger counter and inspect?
Bring your Geiger counter on an airplane flight for a nice education about cosmic rays at altitude.
Bring a Geiger counter to a dental appointment or other medical appointment for which you have an x-ray scheduled, and listen to it shriek when the beam comes on (x-ray machines are very intense sources of radiation, but the beam is on for a split second).
Take it to cancer radiotherapy appointments or nuclear medicine procedures to liven up the proceedings.
If allowed, bring it on a tour of a nuclear power plant or academic research reactor.
Flea markets and electronics swapmeets (“hamfests”) are frequent sources of military or consumer items that contain radioactive material.
I really enjoyed watching your videos from Ukraine What are some of the craziest sources of radiation you have found?
Some of the strongest and most frustrating sources of radiation I encounter are other human beings who have recently had a nuclear medicine procedure. Many times I have been in flea markets or antique malls looking for hot goodies, and I think I’m on the trail of something amazing, only to find that the source keeps moving!
Unfortunately, having a radioactive person around means it’s practically impossible to look for anything else. You just have to wait until they leave the area.
Perhaps the most entertaining radioactive items that I have collected come from only about five miles from where I live: radioactive pieces of a Mark 17 hydrogen bomb that was accidentally jettisoned by a B-36 on its way to Kirtland Air Force Base. The bomb chunks are not hard to find with a regular Geiger counter.
The activity is due to unenriched uranium that presumably constituted the weapon’s “tamper.” You, too, can collect genuine radioactive American H-bomb parts if you come to Albuquerque (please also try our wonderful green chile).
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Is it just me or is there a concerted effort to conceal the whereabouts of typhoon Songda over Japan right now? Can’t find anything on it? Might be kinda important to see which way all that leaking radiation is going.