Well, I’ll admit we are getting a little bit further away from photography than would normally be considered sane but after my last expedition, I have become quite interested in gathering all sort of data during my trips. Radio-activity levels is a fairly easy one to start playing with, even if it is actually quite difficult to master.

I spent the usual few weeks on the Internet gathering information and reading comparisons and reviews but found that, unfortunately, only consumer grade instruments were talked about, scientific grade detectors only being rated on well hidden official reports. Even their elevated prices were difficult to obtain.

The limited information problem was also compounded by a serious lack of availability for the devices in Europe so I settled on second or third choices. That’s where this long winded introduction is finally going: I ended up quite happy about what I bought and I learned a lot in the process.

The best deal on the market has to be the CDV-700 line of detectors. Built in the hundred of thousands during the cold war, they now pop up everywhere and can be had for a song. Two models are of particular note, the actual CDV 700, which is a proper Geiger Counter and has a useful range in everyday life (0 to 50 mR/h) and the CDV 715 which is a scintillator and will only start working at near lethal doses (up to 500 rems/h), long after the 700 has exceeded its maximum reading. As they are old analog instruments, they need periodic recalibration but a little bit of DIY will makes them useful even if you don’t have the powerful radio-active sources needed to calibrate them.

If all the voltages are within parameters on the old analog circuit board of the 700, it will emit clicks in rhythm with the passage of ionising particles. Counting them by hand, or with the help of the fantastic App GeigerBot, gives a fairly accurate indication of the local radio-activity. To get any more meaningful data, you would have to go into determining the emitting material presents and adjust the value according to the specific harm they might do to biological organisms. Most detectors assume they are reading emissions from Cesium 136 and should be calibrated using samples of the material. A 700 in working order will therefore give a meaningful value for background radiation and be able to detect hot spots, something you can experiment with by getting it close to known radio active sources such as old watches Radium luminous dials (scary!) or Fiesta Ware Uranium coloured china.

Up the scale in price and capabilities is a little device made in Germany called the Gamma Scout. It has a lot going for it, the best part being that it is actually available to buy in most countries. It is a bit expensive, ranging between $350 and $500 depending on the model but has many features not usually found until you spend thousands for professional devices.

The Gamma Scout has a checkered history, with the first few iterations being remarkably sub-par and it is still riding a fine line between being a hobbyist toy and a properly calibrated tool but the good surprise was that the latest model, I bought a GS Rechargeable version 6.05L, is a pretty solid performer.

The best feature of the GammaScout by far, is that it is also a dosimeter. Just like with sun exposure, time is just as important as intensity if you want to avoid being sunburnt, or in this case irradiated. To that effect, the GammaScout is always on and counting the particles passing through its Geiger Muller tube so it can give you not only an instant reading, the intensity, but also a total of all the radiation absorbed. Even better, it can store a pretty large log of readings which can then be transferred to a PC via an USB port. This always-on feature has led the manufacturer to opt for a large capacity, permanently installed battery which should last for a long time, 10 years of normal use, but forces you to send back the device to the factory for a replacement. Fortunately, there is now a version that recharges the battery via the USB port and this is definitely the one I would recommend as you are likely to play with power hungry features such as the tick sound output and the PC interface.

The PC software provided with the GammaScout is universally considered as mediocre but it can output a nicely formatted list of readings which can then be used to much better effect in a spreadsheet.  With a lot of hacking, and the help of a piece of fan software a Mac or Linux powered computer could also read the data.

Either way, this is a fantastic way to get good radiation history to make nice curves with and there are not many other options to do so unless your budget is unlimited.

After you have run around the house trying to measure radioactive sources, the most interesting thing to do is to travel with your Gamma Scout. It is probably better to check it in as the little radio active symbol would seriously spook security agents. Back to your computer, you’ll see very interesting peaks where your luggage was x-rayed but mostly, a ten fold increase in radiation as you got away from the ground. It is a well know issue and the quantity of radiation you get at 30,000 feet makes the odd x-ray visit or having a tritium key chain quite innocuous.

I just took my Gamma Scout to Iceland and noted that the young, basaltic island gave off a third of the background radiation our old, granite island does.

The Gamma Scout is not sensitive enough to help you find low level radio active sources but it works well with background radiation and medium level sources, all the way to 1 Sievert. It would be a fantastic tool for managing a Fukushima-style nuclear emergency at the personal level by telling you which areas of your house are safer to stay in and whether it is safe to venture outside and for how long. It is also very good for my purpose of adding one more variable to my environment readings while out on expeditions.

I think Dr Mirow has now made a perfectly usable device and there is little I would like to see changed on it: I would love to have it behave as a standard USB storage device with all the readings already neatly organised as readable CSVs. I would also like it to be more seriously calibrated although I do understand this might take it completely off the category of affordable devices.