Photodiode Gamma Ray Detector

More progress on gamma photon detection using junkbox photodiodes.

Category:

Science & Technology

Tags:

• vk2zay
• gamma ray
• gamma photon
• photodiode
• radioactivity
• thorium
• uranium.

[smartpartzzkidd]

have you tried using a piece of dark paper instead of Al foil? if detecting energy level jumps, do you know the series for the material in the photodiode?

[vk2zay]

@smartpartzzkidd I tried lots of window materials, papers are too transparent it seems, the photodiode is very sensitive to light, and even with high-pass filtering ambient light leaks saturate the detector easily or induce so much buzz you can't discriminate the pulses from gamma photons. Mylar is also too transparent, and the leafing foil I have has tiny pinholes!

[tesla242]

Great! I will be anxiously waiting for the schematic ;) seems quite simple, and once its calibrated , plus using an array of photodiodes, make a remarkables simple pocket detector!

[vk2zay]

@tesla242 There is a limit to how many photodiodes you can parallel, their capacitance is a problem... About six at most I suspect, but you could give each it's own buffer transistor and make large pixellated arrays. Because the capture volume is so small it will never rival a big scintillator or even a modest GM tube in sensitivity, but it is very cheap (~$3) and rugged.

[U235hexafluoridedude]

Your photodiode counter should work as a MCA if you were to run the signals to the soundcard of your computer using PRA. The peaks are energy dependent and a non PRA gamma analysis with a photodiode was done by a fellow by the name of Thomas Rapp a few years ago. The energy resolution was quite admirable for such a tiny thing, although any detector's energy response is limited according to it's mass, in this case you're stuck in below about 100KeV or any meaningful data.

[rodjownsu]

Nice work! it's amazing the capabilities of some readily available components....

[bkelektronik]

Thanks for the nice comparison diode/GM-tube. Only about 1 count per minute with no source is what I also found.

[tesla242]

@vk2zay Thanks for your answer. Yes , I was planing to do a separate buffer each 3 to 5 diodes, a "solid state detector" it´s been in my "to do list" for a long time. A thing you can carry in your pocket and uses a few microamps, could be interesting.