Materials:
- Webcam (http://ali.pub/3j30am);
- Thin food foil;
Operating principle of the sensor
The webcam matrix consists of photodiodes (pixels), which, when charged particles hit them, generate an electrical pulse. Such visual flashes are registered by the camera chip. This data is analyzed by a special computer program that allows you to determine the presence and quantity of emitted radioactive particles.
The camera matrix fully responds only to beta particles and a little to gamma rays.It is almost impossible for alpha particles to pass through the filter of such a sensor. The program records frames with flashes of the electronic trace of isotopes on the camera matrix over a certain time, adjusts them into one photo and counts artifacts.
Webcam conversion
The front housing cover is removed from the camera.
Near its lens you need to desolder Light-emitting diodeto avoid glare.
The lens is unscrewed from the camera counterclockwise to reveal the matrix. If it doesn't rotate due to the compound, you just need to apply more force.
Instead of a lens, a piece of foil is attached to the matrix.
After laying it down, the camera body is put back together.
How to use the detector
The camera is connected to a computer with the “Theremino Particle Detector” program downloaded and running. In the main program window you need to select a webcam. After this, a small window with parameters will open. You need to set the settings in it as in the photo. It is important to check the box next to the “Exp.” slider.
First, the natural radiation background should be measured. In the program, press the “Start” button. The panel will begin counting down the time in seconds. After 1000 seconds you need to click “Stop”. During the countdown period, you should refrain from using the keyboard, as this will disrupt the settings in the program. Under the timer, in the “Patricles” line window, a number will appear with the number of radioactive particles recorded during this time. There will be a few of them, 10-20 pieces.
Next, you need to place an object with a likely increased background radiation close to the camera lens. The program runs for 1000 seconds. After this, you can get results with a fixed number of particles. In this case, a dark photo will be formed on the part of the program window that is responsible for displaying the image from the camera.It consists of frames superimposed on each other, taken by the camera over 1000 seconds. If there are radiation particles, then their flashes on the matrix in the form of light small dots will be visible in the black picture. With significant radiation, the photo will begin to resemble a starry sky.
Examples of analysis of various radioactive substances
Such a detector can respond to uranium glass, which gives an α, β and γ background of 210 μR/hour.
This is a completely safe sample for humans. The device receives 24 pulses from it.
When analyzing also a relatively safe thoriated electrode from a DKST lamp with a general background β and γ of 500 μR/hour, the program identifies 61 particles.
The active drug americium 241 from the HIS-07 smoke sensor with a dangerous background of 11.3 mR/hour, mainly emitting α and γ is also detected by the camera.
It has 299 impulses.
The camera reacts to radium 226 from the luminous composition on the hands of old wristwatches with a background of 9.17 mR/hour.
The program contains 1010 impulses.
When analyzing uranium ore with a background of 21.2 mR/hour, 1486 particles are determined.
Source 1 from a Soviet smoke detector with a background of 61.3 mR/hour, bombarding the matrix with americium 241 and plutonium isotopes, when analyzed, produces 3707 particles to the sensor.
The control source B-8 from a military dosimeter with a background of 52.8 mR/hour creates 11062 flashes on the matrix.
A very dangerous control source BIS-R with a background of 826 mR/hour projected 15271 particles onto the sensor.
In fact, the sensor and the program determine how many particles flew out of the emitter and landed on the matrix. This is enough to understand that the sample being studied is radioactive. The only drawback of the sensor is its wear. A truly radioactive sample, such as BIS-R, will simply ruin the matrix.
