Gamma Spectrometry Forum

Electronics are sensitive to ionizing radiation. With silicon image sensors, it is straightforward to detect the traces left by atmospheric muons and high-energy electrons. One just needs to get access to the raw sensor data, before any noise reduction or data compression. The Raspberry Pi and its Pi Camera are almost ideal for this (and inexpensive). Its pixels are 1.4 x 1.4 um in a 1944 x 2592 array.

This is a work in progress, but I am getting somewhere. The program takes long exposures. If there are pixels brighter than some threshold, it will write an area of 50x50 to disc. The code can be downloaded from GitHub: https://github.com/pietkuip/raspberrypi_muon_microscope

Most events are "spots", clusters of a few bright pixels, probably caused by particles moving at a steep angle to the sensor plane. Then there are "worms": curved or meandering traces, sometimes going "subsurface". Muon tracks are rare. Here is the longest one so far: To do: update documentation, re-introduce a screen display of the data, maybe display data on an 8x8 led display.

Interesting ! What is the position of the camera, vertical or horizontal ? Di you try to "irradiate" the pi camera with an electron source such as Sr90 ?
Lodovico

lodovico wrote:Interesting ! What is the position of the camera, vertical or horizontal ? Di you try to "irradiate" the pi camera with an electron source such as Sr90 ?

The sensor plane is approximately vertical. Landscape or portrait does not matter now, but I will specify this when I have a stable setup.

For testing the code I use a 370 kBq americium source. The sensor then reacts immediately, probably to the 60 keV gammas that produce electrons in the silicon. I have not looked into that yet. There will be many different energies: compton, photoelectrons, Auger electrons, I will read up on what one should see. And I will test with our Na-22 positron source, if one could detect annihilation events.

A question : Did you remove the cover glass from the CMOS sensor of the camera ?
Lodovico

Hi Pieter, I tried to imitate your setup for Raspberry Pi microscope but when I start getrawimage.py, I get ImportError : No module named scipy.misc.
Do you know what went wrong? I did perform sudo apt-get install python3-scipy python3-picamera and the other two .py files seem to work.
Screendump attached

lodovico wrote:A question : Did you remove the cover glass from the CMOS sensor of the camera ?
Lodovico

Sorry, I had not logged in for a while. No, I did not remove anything, I just wrapped the camera in black electrical tape. Cosmic muons will penetrate anything, many meters of concrete.

I used the NoIR camera (no infrared filter), but that does not matter at all for this application.

Yes,
For the muons the cover glass is not a problem ..
I was just thinking about the possibility to use the webcam as a particle detector in order to catch also alpha, low energy beta, etc .. but the cover glass stops many of them. I tried to remove the cover glass from one of my webcams but it is not easy at all and eventually I broke the chip. I wonder if someone knows a way to remove this cover or knows a way to get a webcam chip without that cover.
Thank you,
Lodovico