MicroTeslas As Gamma Radiation Unit

Question

I live in Poland and currently due to international situation (War in Ukraine) there is quite high risk of nuclear attack here. I also live in capital which makes it most probable target. This is why I wanted to install an Gamma Radiation Measuring App on my phone. I have read that such applications exist and they measure radiation "using CMOS matrix". However I could only find ones that use external dongles. Eventually I have found app called "EMF Radiation" that works and measures... something. It shows values in microTeslas, so it measures magnetic field flux. I have few questions about it:

1. Does this have anything to do with gamma radiation? On Wikipedia I have read that EMF covers variety of radiations including alpha, beta and gamma, however when reading about Tesla SI unit description I could only find information that it is used to check magnets power.
2. So can such an app give information about gamm radiation at all? And if so is there a way to convert value in microTeslas to for example Sieverts?
3. If this has nothing to do with gamma radiation, do actually "apps that measure radiation using CMOS matrix" exist? I could not find one.

Answer 1

Your eye detects light. Light has a wavelength. Your eye is sensitive to a narrow range of wavelengths. Red light has a relatively long wavelength, and blue has a shorter wavelength.

Light outside of this range isn't visible. There are a variety of names for it, depending on the wavelength. Infrared light is just a little too long to see. Radio waves are way too long. EMF is longer still.

On the shorter side, there is ultraviolet, Xrays, and gamma rays. Shorter wavelengths are more energetic and dangerous.

Your phone has a camera that is sensitive to roughly the same wavelengths you are. So asking your phone to detect gamma rays is a little like asking you to write down a note every time a gamma ray passes through you. How would you know? This is the reason for dongles. They would be a detector built for gamma rays.

However, all is not lost. Gamma rays are so energetic that they sometimes produce a flash of light when they travel through something. Your phone or your eye can detect that if the gamma rays are intense enough. This is not the kind of environment you want to stand around in looking at your phone.

However, people have written apps that use this. Here is an old report from Brookhaven National Laboratory on an early attempt. Test GammaPix Radiation Detection Software with Smartphones

The upshot is that it doesn't work very well. If you are interested, investigate apps that require a dongle.

However, you might consider a few more things first.

Nuclear weapons often generate an EMP (electromagnetic pulse). This is a very long wavelength pulse of light so intense that it generates a giant voltage spike. It tends to fry electronics. So if there is enough gamma radiation that your phone could detect it, your phone might not be in working order.

Also if war comes to a city, one of the first things to be attacked is infrastructure, like power stations. You might have a hard time charging your phone well before things got to the level of nuclear weapons.

Answer 2

EMF radiation is the low frequency radiation from power lines and appliances. Not gamma rays. Not the result of nuclear reactions. Not generally thought to be hazardous at the levels you commonly encounter (but people selling these dongles will want you to think otherwise).