The op amp chip is in an 8 pin DIP. The capacitors, the photodiode, and 8 of the 9 resistors are all in packages with leads. The switch and BNC connector can easily have leads soldered to them
Then there is R3, a 40 M resistor that the parts list calls for getting as in SMD. In fact, the parts overview link specifically calls for a black SMD.
As far as I can see, R3 is the only thing that needs a PCB. Everything else would work fine with a solderless breadboard, or any other common non-PCB hobbyist electronics construction method.
Is there some reason R3 has to be black and has to be an SMD resistor for this thing to work? Looking at the schematic it appears to just be part of the feedback loop to control the gain of the op amp in the first stage amplifier, which should work no matter how one decides to get 40 M of resistance.
Please don't be put off by the circuit board requirement, I have listed it on kitspace such that it is really easy and cheap to get one: https://kitspace.org/boards/github.com/ozel/diy_particle_det...
Even if you have never ordered a PCB, it should be straight forward using kitspace as a proxy to get it right.
For beginners, I would propose soldering the electron-detector first (on the plus side, it has 4 times more the sensitivity) and if that works swap few parts and upgrade to the alpha-spectrometer variant since that is a bit more tricky to operate and get running.
I've commented on the through-hole/SMD choice and similar questions in this twitter thread https://twitter.com/0zelot/status/1260931205676990466.
In short, I choose leaded components over SMD where possible such that it is easy to solder. But analog signal integrity and low noise vs. signal require a circuit board.
The first op-amp is used as a charge amplifier. A high energy charged particle will deposit a charge Q on un-grounded node of the reverse biased diode. The voltage on the output of the amplifier is V_out = -Q/C_feedback + V_bias, where v_bias is made with the voltage divider on the non-inverting input. The resistor R3 is only used to adjust the frequency response (and I assume stability) of the amplifier. It will low pass the signal at ~800 Hz.
The problem and the reason they want you to use small low capacitance components is that in order to get a large charge to voltage conversion factor, C_feedback is small (5 pf). If you build the circuit on a breadboard and place the op-amp output and input on consecutive lanes then parasitic capacitance can easily add another ~10 pF to that and drop your amplification.
To get around this, you'd have to lift up that leg of the capacitor and solder your connections to it instead. This will avoid stray capacitance from lowering your gain.
The opamp appears to be configured as a transimpediance amplifier. 40M is a lot of gain. Probably keeping traces short and the resistor away from the board helps. That’s probably why they mount the resistor vertically when they use a through hole in the pic above (my guess anyway). Using a SMD keeps the traces short, which might be why they use it in the current version.
Another option could be just to air wire the resistor. Sometimes people bend up the legs on the opamp and wire the resistor/input directly to the IC pin.
I think you might have issues on a breadboard. Air wiring the whole thing would probably work. Or using protoboard, trying to keep the traces short.
That's the "electron-detector" version, which uses a 10M feedback resistor. The alpha-spectrometer version is the one that uses the 40M SMD resistor.
Paper (Open Access, click "Download PDF"):
* Smartphone and Tablet-Based Sensing of Environmental Radioactivity: Mobile Low-Cost Measurements for Monitoring, Citizen Science, and Educational Purposes
Dry ice is pretty easy to get at Graeter‘s if you have one of those local. Just don’t store it in a closed container. Gloves are a great idea of course but I also advise wearing thick socks or slippers when you’re using it. Stepping on even a very small piece of dry ice in bare feet is experience you will remember.
Dry ice is a lot of fun but doesn’t last long. If you go through this, check youtube for other experiments and things to do, and buy a little extra. Just remember never put it in a closed container, it will almost certainly explode. Physics doesn’t care about you, respect the material. (edit: I just checked, heat of sublimation of CO2 is approximately 570 kJ per kilogram. A stick of dynamite has approximately 1 MJ. There’s a lot of energy cached in those blocks.)
I've never built one but it's always something I plan on building.
Dry ice is the other problem it's not something readily available in my town. I don't think regular ice is cold enough especially when using isopropyl alcohol which isn't as volatile as methyl alcohol (methanol).
Yes, this project is very much doable for electronic beginners with a knack for science (16-year olds who have never soldered manage it well if guided a little bit). The parts are easy to solder and ordering the circuit board will make your life much easier in order to get it working.
BTW, no one earns money with the kitspace website above. This is community-run and intended to make open hardware projects easier to build by simplifying the ordering procedures. The parts and board suppliers linked on kitspace should cover most of the world.
This one uses plastic scintillating material in front of the detector.
In terms of difficulty to build and operate it, I would rate the discussed projects such:
cloud chamber < DIY particle detector (electron-detector variant) < DIY particle detector (alpha-spectrometer variant) < desktop muon detector
Even DIY cloud chambers can be a bit tricky to get running for the first time (especially with too high humidity like in summer). Just don't give up! ;-)
A few tips can be found in this manual: https://scoollab.web.cern.ch/cloud-chamber
If you look closely in thought emporiums video (link below), the thick clouds - representing each the full paths of individual alpha particles (from the point of decay until full absorption in the air) - don't originate right at the surface of his shielding materials (paper, chicken skin... whatever). Instead, the alpha particle clouds stand by themselves in free space and can only really stem from radon that decided to decay at those positions somewhere outside of the shielding (transforming to "solid" polonium in that process and sticking itself to the next closest lump of molecules/dust). If the alpha particles would penetrate the shieldings (which they can't because of too much material/density), we would see clouds stemming directly from the shielding surfaces which I don't see happening:
You may find and like my comment there, maybe it helps to fight some misconceptions about natural radioactivity. ;-)
It's fine for what it is. But I think a particle detector that most people imagine is really something you want to be able to hold portably in the air and detect ambient/impinging radiation from unknown sources, rather than have to put samples in a closed container.
If there were some modification that made that possible (getting around the light-tight requirement), that would make this incredibly more useful.
Even the glas covering the diode has to be broken away / removed