Semiconductor radioactivity detector: part 3


Robert Gawron has made a new version of his radioactivity detector project and wrote a post on his blog detailing its assembly:

In this post I will present a new hardware version of my sensor, older versions are described in part I and part II. In comparison to the previous one, sensitivity is roughly x10 more sensitive.
In previous version, tin foil window for photodiodes was very close to the BNC sockets and because enclosure was small, it was hard to place a sample close enough. Not it’s better, however, if I would choosing again, I would use metal enclosure similar to those used in PC oscilloscopes and put BNCs on front panel, power socket on rear panel and tin foil window on top. This would allow me to easier access for debugging- now I have to desolder sockets to get to photodiodes or to bottom side of PCB.

See the full post on his blog.

Semiconductor radioactivity detector – part 2


Robert Gawron has been working on a radioactivity detector, that is available on GitHub:

There are many ways to measure radioactivity level, semiconductor detectors sense interactions between ionizing radiation and p-n junction. Because in hobbyist area most popular are Geiger-Muller based detectors (in short: not a semiconductor but lamp based devices), I think it’s a cool idea to take a look at this approach.
In this post I will present such home-made sensor and a set of software to parse collected results.

See the full post on his blog. Be sure to see Part 1 here.

Radioactivity detection using very simple ionization chamber and a single J-FET transistor


Robert Gawron writes:

Today I will show a very simple ionization chamber that can detect radioactivity. I was able to detect with it ionizing radiation from a smoke detector (Am241 isotope). It’s also immune to electromagnetic interference (EMI) due to a good shielding.

This device doesn’t explicitly use any power supply. It’s connected to a multimeter set to measure resistance, in this mode, the multimeter provides a small voltage to its probes (R=I/U, so to measure resistance, it has to put voltage across measured element). This is sufficient here, because basically we just need to polarise electrodes of the ionization chamber and nothing more. My multimeter provides 5.6V in this mode.
My setup is presented below, note that the sensor is this metal box, not the PCB visible on the image.

More details at Robert Gawron’s blog.

Semiconductor radioactivity detector


Robert Gawron has been working on a semiconductor radioactivity detector project:

Currently I’m trying to make a working version of a radioactivity detector that uses semiconductor as a sensor. It’s a different approach than Geiger-Muller detectors, more complicated, but also much more interesting.
While Geiger-Muller counters can only provide information about the amount of particles in a period of time, semiconductor detectors can also measure their energy, so it’s possible to say much more about the nature of observed ionizing radiation. Some of the disadvantages of these detectors are that they are more expensive, complex and sensitivity may degrade over time.

More details at Robert Gawron’s blog.