Radioactivity Counter

457 reviews
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About this app

Radioactivity Counter

This is a real working radioactivity counter. You only need a BLACK TAPE to cover the lenses !!

Disclaimer: The type of radiation picked up by the camera can be dangerous/detrimental to the user's health as well as cause damage to the device.

Its NOT a JOKE! The App is using the camera sensor to detect radiation, like a geiger mueller counter, of course with a smaller area. We tested several mobile phones at the Helmholtz research facility in Munich, using a professional radiation device in the range of 2-10 µGy/h till 1-10 Gy/h (CS137 and CO60). The CMOS sensors can detect primary gamma radiation and some higher beta radiation (depends on the shieldings in the mobile phone). Typically not going into saturation as most GM tubes. See FAQ on our homepage for what you can measure and how.
PLEASE SEND US FEEDBACK via EMAIL !! We add new devices in short intervals.

Attention: the tape must shield the light completely. Please check with a light source !
On our homepage you find several measurement result for different devices we tested so far. Some are excellent, some not that sensitive.
Feel free to use our table to assign radiation values to our counter measurements when you have the same device.
The real values might differ as sensors can change. There we need your help and the help of the manufactures for a future calibration service.
You can use the contact button in the help menu to provide us with feedback and please use it.

If you need any help, PLEASE send us an email. We have cannot answer the comment section below, so please ask us first on measurment problems. We help as fast as possible. Please contact us on any problems you have with this application! Look at our videos, more are comming soon. Attention: The counts per minute (CPM) for the background noise should be low (increase the noise setting if not). This is camera noise not radiation noise basically. If the radiation increases then also counts from the radiation adds to the CPM values (see our tables for the sensitivity). If you have a phone with 200 CPM for 100 uGy/h then the background noise produces for 100 nGy/h only 0.1 CPM. That means in 10 minutes ONE counts in 100 minute TEN counts adding to the CPM0 (noise of sensor). So you need a LONG time to measure for low radiation values on this device. Attention: AM241 (smoke detectors) only emit ALPHA rays, they get stuck in the plastic of the phones. H3 (tritium - watches etc) are beta emitters with 45 keV. They also get stuck quickly, mainly already in the watches. K40 (KCL for example contains 16 Bq/g) are beta emitters with small amount of gamma (due to positron collisions)- you need also a long integration time to measure them. Same for TH rods (2% Thorium) mainly alpha rays, then beta and some gamma. Very small diameter ! You need a large area to detect them (best GM with mica windows). The CMOS sensor of the camera only has 2mmx2mm.
Good objects are TH lenses (up to 30% TH232), pitchblend (gamma of decay products) and CS137 for checking food which might be contaminated (if larger 1 uSv/h). Don't experiment with radiation sources !!!

* saving raw counter values in 3 different noise levels
* saving temperature data
* saving location (optional)
* saving settings data
* export by email (CSV) or file, CSV / HTML
* export of mean values in Counts + standarddeviation
* unit converter (Sievert, Gray, Rem...)

We just released a comprehensive help on our homepage --
Important you NOISE value should be similar as in our tables, if it is too high check the tape to cover the lense - use multiple tapes if necessary and start calibration again !!! Please before writting a bad one star comment write us we will help you very quickly PLEASE !!!
more videos on our homepage -

instruction and help:
some more:
Updated on
May 31, 2018

Data safety

Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region, and age. The developer provided this information and may update it over time.
No data shared with third parties
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No data collected
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Ratings and reviews

426 reviews
Ron Henry
August 18, 2022
This detector works and works well! It cannot tell you what flavor the particles are but I have detected alpha and beta emissions from Granite and Gamma emissions from PET scan Glucose. It detected all! The way this works is understood well with digital Astrophotographers. Radiation causes the photo sensors to "white out" resulting in fake stars. We use software to remove them. This is a clever use of what was considered a weakness in CMOS sensors. DOES NOT work on Android 12 :-(
9 people found this review helpful
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A Google user
January 5, 2019
I have Samsung Galaxy Note 9 and I needs to be a way to change it to the rear camera because the front camera keeps picking up light from the screen, for example in the notification tab gets pulled down I've tried everything for foil, duct tape foil and duct tape. Electrical tape as well but everything still lets light in
18 people found this review helpful
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A Google user
August 8, 2019
app works. I get a linear dose response from various CS-137 sources. however it is glitchy and sometimes freezes or dies when switching from front to back camera. please update software functionality.
8 people found this review helpful
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What's new

rev 2.1
new datat privacy hint.
rev 2.0
new menu button, several internal function update. And currently test url for uploading data (will be provided to test users)
rev 1.8
new split modus, for better noise handling with low radiations. Help updates new design. Support for the new OS versions. Less permissions needed.
rev 1.7
* higher cover lense level for some phones required.