Member Since: February 12, 2011

Country: United States



Former CTN (Cryptologic Technician Networks) Malware reverse engineering Booz Allen Hamilton Security Researcher



Spoken Languages


Programming Languages

x86 assembly, C, C++, Java, C#, MIPS assembly




Computer Security, Reverse Engineering

  • Using dose units is pretty meaningless because they'll be wildly inaccurate without proper calibration. Radiation detection instruments outside of some specialty ones are typically calibrated to Cs-137. You have a rig that puts the instrument at a precise distance of known calibrated activity and energy and use that to calibrate the unit which is the conversion factor for CPM/CPS to dose rate, which is only good for that individual instrument. There are more factors to consider like using Hp(10) or H*(10) dose calculations. H*(10) are normally search instruments, and dosimeters use Hp(10) which is the dose calculated at 10mm penetration in a flesh analog. Also exposure rate varies dramatically with distance dosimeters have to be worn on the body. The chest preferred for whole body exposure. It gets more complicated with weighting factors(Wr) for type, body parts, and organs to calculate the final dose.

    Once you have it calculated it will only be accurate for Cs-137 which, and I'll use only gamma energies for this explanation, emits gamma photons at 663KeV. Another, say Co-60 emits gamma photons at 1.173MeV and 1.332MeV. So in layman's terms a single count from a Cs-137 source will have less energy than a single count from a Co-60 source. I'm going to use uSv/h but to be totally correct it should be uGy/h for absorbed dose, so I'm using a weighting factor of 1 for gamma rays to get the uSv value for what a whole body effective dose rate would be theoretically. At 37kBq @ 1cm with a 100% theoretical exposure the H*(10) dose rate from Cs-137 would be 28.3 uSv/h, Co-60 would be 113.7 uSv/h, and very common Potassium-40 (K-40) would be 6.8 uSv/h. That's why using dose measurements with a geiger counter, unless you have a known source, is fairly pointless. With unknown sources such as background the standard to use is CPM or CPS for good reason. There are ways to energy compensate a GM tube so it can be used in dosimetry which essentially puts a material around the tube to level out it's energy response as much as possible. Dose will still be inaccurate for anything it's not calibrated for, but less so than without it. The trade off is it loses some of it's detection sensitivity. That doesn't matter for a dosimeter, but it does for a general purpose instrument.

    Also be aware that count comparisons between different instruments are not always accurate unless they use the exact same GM tube, and even then the detection circuitry can affect things. Every model of geiger tube will have different count rates. Larger tubes tend to have more than smaller ones. Different tubes also have different detection efficiencies so even with very similar sizes if there's a source energy that ones tube is not very good at detecting there will be difference in count rates.

  • I can't agree more. Bre Pettis talks up open hardware and software in public and then turns out to be a hypocrite when someone does what the very thing he spoke so strongly for when someone actually does it.

    Improvements don't have to be about design or software. It can be as simple as being able to make it cheaper.

    The Arduino is a great example. It's been copied countless times and is still going strong.

  • It's a cool concept but considering you'd have to buy multiple sets to really do much with it, and there is no charger included for $160 I'll pass.

  • Just have to insert the control rod a little bit further...

  • Use the same profile as Kester EP256, works perfectly. The non-metallic composition may be different but the melting point of the metals are the same.

  • If you're using Hakko for production are you going to sell the T15 series tips? I normally order from Hakko but if you carry them I'll give Sparkfun my money instead just because you guys rock.

  • Hands down one of the best irons you'll ever use. You don't need an FX-951 unless you need the ability to lock temperatures for production environments or just want the top of the line iron. The FX-888 is honestly overkill for hobby work. It's an industrial iron so it's going to last a long time.

  • Check here
    They have some other kits but make sure the tube used detects at least beta and even better if you can find an alpha/beta tube. They have a lot of gamma only tubes that won't be as useful.

  • I spent about 3 years within a 150ft of a nuclear reactor. I was stationed on an SSN early in my navy career. My exposure underway was actually less than being in port unless I spent a lot of time aft where the diesel tank doesn't provide additional shielding, but even then I was still nowhere close to my exposure limits.
    What I find amusing about this is people are buying up old cold war era civil defense meters and all but a couple of models only detect high energy gamma emissions that would be expected from a nuclear attack. I was trying to bid on one of those old units to gut and use as a project enclosure but even with the broken ones I was getting outbid rather quickly.
    The particles seen in the US will be primarily be alpha and beta anyway so those gamma units are pretty useless.

No public wish lists :(