> The Cogamo detector is a small (23 cm × 28 cm × 10 cm) and lightweight (3 kg) radiation monitor, using a CsI (Tl) scintillator (5 cm × 5 cm × 15 cm) coupled with a Silicon Photomultipliers (SiPMs) MPPC (Multi-Pixel Photon Counter) as a photo sensor (Figure 1b). The energy range for gamma-ray spectroscopy is the ∼0.2–10 MeV band. The detector acquires the energy deposit and arrival time of each radiation event and records them into a microSD card. The time tagging is performed using GPS signals. In addition, 20-s bin count rates in six energy bands for 0.2–0.5, 0.5–1, 1–2, 2–3, 3–8, and >8 MeV, GPS status, ambient temperature, humidity, and optical luminosity are recorded on the microSD card and are also sent to the web server for a quick-look purpose. An observation is started simply by connecting a GPS cable and a power cable and then turning on the power switch. Energy calibration of the Cogamo detector was performed for each file of one-hour data when analyzing, using environmental background radiation lines of 40K (1.46 MeV) and 208Tl (2.61 MeV).
Is the state of IOT such that these kinds of sensors and measurements are widespread and reasonably priced? Where can I learn more?
More or less. What do you consider reasonably priced? The sensors aren't particularly special. PMTs are used widely in science for photon counting, but maybe the ones they chose have some specific characteristics.
Most of this system is very fast readout circuitry - fast ADC. You need an FPGA to get the data off at 12-bit 50MSPs.
The expensive stuff is probably the PMTs from Hamamatsu and the power supply from Matsusada. They will certainly give you a quote, but their sensors can be pretty pricey. Probably hundreds each for the PMTs and that again for the power supply. Hamamatsu are the experts and they have a good monopoly. Edmund sell some pre-packaged tubes for example: https://www.edmundoptics.com/f/hamamatsu-photomultiplier-tub... (but Edmund are always $$$)
Everything else is glue really, with a custom PCB for the data capture. Though some of the components like the FPGA and the ADC are $50 each (and there are two ADCs). I don't know if they would release this open source, but I suspect not (which is a shame).
As is typical with science, the authors emphasise how they designed this to be a low cost system, but never actually say how much it cost. I would hazard a guess that you could do this for under $5k BOM cost (ignoring design and labour) if you planned it well. Let's say $500-1k for a crystal with some provenance, $2-3k for optics and $1k for the circuitry and housing. Might be well off on the crystal if you have to buy it from somewhere reputable though. You could probably MacGuyver something for a lot less if you could get away with bits from eBay.
With a bit of creative scrounging you could put something together for less than US $100, I imagine. The budget would probably be driven by the question of whether the surplus pager scintillators are sensitive enough to observe the effect.
As soon as you're into surplus for sourcing parts you've essentially done an end-run around your target pricing: it will work, for a very limited run and then you find the 'true cost'.
What would probably be better is to see what design limitation crop up if you try doing it for say $1000 without any surplus parts.
Yep, a lot depends on the size of the 'production run.' The seller had over 3000 of those scintillators originally, not clear how many they have left.
Digitization is another question -- they used a fast FPGA-based digitizer but it's not clear why it was necessary given the duration of the events being recorded. If it really is needed, then driving the cost down on the digitizer will be as big a challenge as the scintillator itself.
That's a neat little stash then! Wonder where they got them. I used to frequent government surplus auctions and the weirdest stuff would turn up. 10 tons of spare parts for a Magirus-Deutz vehicle that hasn't seen active service since the 50's, five containers full of used army boots (but without the containers), a veritable mountain of laptops sans harddrive and with various unknown defects and so on. I would occasionally buy something and usually got something out of it (profit, some useful tool) but on the whole the quantities of the lots were such that only people with both lots of space and lots of money at the same time would be serious bidders on those lots.
Even working as a scientist, I buy equipment from eBay. If you bide your time, you can find useful bargains. In fact, even when my budget can accommodate new gear, there can be exceptionally long lead times, whereas an eBay seller has it on hand and will ship it out tomorrow.
This makes it harder to copy a documented design, of course, but most of the time a scientist with a knack for gear can adapt things as easily as copying them.
Also, people did photon counting for a long time without 50 MHz ADC's, just saying. ;-)
it's not using PMT's it's using silicon photomultipliers, those can be had in the $5 to $10 range. At first sight the most expensive part seems to be the CsI crystal.
Perhaps polystyrene or PMMA or another transparent plastic could serve as a cheaper alternative, but probably at the cost of energy resolution, although this study binned the energies anyway.
The collaboration has been measuring since ~2016 at least, so they have multiple generations of sensors installed. You capitalize and emphasize "the arxiv Paper" as if the group published one paper only as if they are from then on forbidden to explore other sensor constructions.
The parent article describes a more recent iteration using silicon multi-pixel photon counters (MPPCs aka Si"PhotoMultipliers" SiMPs).
When I said $5 to $10 range I was referring to some of these for example (did not thoroughly search for the lowest priced across distributors right now):
The 2007.13618 Thundercloud Project paper is excellent and has a fairly thorugh breakdown on the various bits of hardware and crystals used at different iterations of the project.
No detailed costings (save for the raspberry pi, mobile card + plan (to remotely relay data)) but a good guide.
As with all such projects I dare say the software costs were $0 being measured in graduate student time.
Gamma ray spectroscopy has all sorts of fun applications. I wanted to build one to characterize radiation in food and other objects. Geiger counters are typically not sensitive enough to detect trace quantities of contaminants as they do not produce significant radiation above normal background. You are also unable to measure energies and identify radionuclides. It takes a fair amount of shielding if you want to make accurate measurements though since there is so much background noise in the typical environment.
I'm curious if you can also detect matter which has been activated from the high energy gamma rays. Photon activation begins around 6.2 MeV and really gets going above 10MeV. The gamma rays have sufficient energy to activate the nuclei of stable isotopes, causing them to become unstable, potentially decay and produce secondary radiation.
I was really hoping to put together a setup, but some jerk picked the lock on my storage unit and took all of my radioactive samples and measurement tools. FYI, the typical 'high security' circular locks are easily picked now and with most storage facilities allowing anyone with a storage unit unchecked access to your lock, it's very easy for the thief to go unnoticed.
Do you have any lock recommendations? My storage unit was broken into a year ago and I replaced the locks with those circular ones you’re referring to!
The gamma ray spec is a spectrometer and not just a detector that gives the exact energy of a radioactive decay so it can tell you what exact isotopes are present.
The energy resolution of scintillation counters like those is rubbish, and spectroscopic results obtained with them can be misleading as a result. We initially used NaI just to surround high resolution Ge detectors to reject Compton scattering events which deposit only part of the gamma energy in the Ge. However, the lumps of hyper-pure Ge you need to do high resolution spectroscopy are expensive and need to be cooled with liquid nitrogen.
This isn't really relevant, but I dislike the term "citizen scientists."
It seems to imply that those working within formal institutions are normally the only ones capable of "doing science," and that it is somehow abnormal to consider mere civilians as even minor participants in the scientific process.
Of course, there is no precise line between science and just gaining everyday knowledge through observation or experimentation, something all of us do, to a greater or lesser extent, all the time. So it makes little sense to see "scientists" and "citizens" as two sharply distinct groups.
I read it differently, like the term "amateur scientist" that has been used in the past. To me, it's a term of respect, acknowledging the fact that it's hard to do good science without institutional support, uplifting when someone does it, and spectacular when it's a major discovery.
And oddly enough, people defend science by pointing out that it's like what most people do all the time, but perhaps conducted at a more sophisticated level.
I'm also defending science by, as you say, pointing out that it's like what most people do all the time. But it's precisely for this reason that I don't think that one can draw any clear distinction between scientists and non-scientists or see scientists as somehow distinct from "citizens."
Of course, we can use various terms to describe people belonging to specific institutions or working in specific disciplines, but I don't think it makes any sense to draw a general distinction between "professional scientists," "amateur scientists," and "non-scientists." (Few, I think, consider "amateur" a compliment.)
"amateur" and "professional" have pretty precise definitions: a professional X is someone who is payed to do X, an amateur X is someone who does X without being payed for it.
So, someone who does science without being paid specifically to do science is quite appropriately named "an amateur scientist".
Yes, they're not "citizen scientists", they're just scientists.
How many people's job title is "scientist"?
Debt from a PhD doesn't mean your science is necessarily more rigorous or valid; it may imply you have a higher budget, or it may not.
I bought a copy of "astrophysical techniques" by C.R. Kitchin the other day; that's probably the same book the "real scientists" have -- if I set up a detector network and write the software to manage it and write a paper about it, all built on funds from my automation company, am I less of a scientist simply because I dropped out in the first semester of my freshman year of high school?
I don't know, the data and test rigor are the same either way.
No, the effort and rigor required to do good science is beyond what people can acquire by accident. The first research project that people usually do almost on their own is the _PhD project_. I wouldn’t even call undergrads „scientists“ and the projects they do are more scientific than this (the citizen scientists in this case installed boxes with sensors at their place. There is little science in this tbh.
Another exercise: replace „scientist“ with other professions and see whether you would agree that the term makes sense: „citizen software engineer“, „citizen doctor“, …
I had heard that thunderstorms generate gamma rays before, but I assumed those were produced by the lightning. Apparently I assumed wrong and it might actually be the other way around. Very interesting.
I was involved in atmospheric physics about 30 years ago and back then there were two competing theories for thunderstorm electrification, neither of which made complete sense. My understanding is that it is still like that today.
The incredible release of all kinds of radiation (including gamma rays) around major earthquakes is very interesting from this perspective too.
Which makes me wonder: would this hold true for other planets that have thunderstorms over them as well and could we detect this here? Or is attenuation due to distance such that the signal would be lost in the noise?
From the figures in the paper, it looks like some of the detectors started picking up an increase a minute or more before the lightning flash. However, 2-3 of the detectors also picked up increased gamma counts that then died out before the flash. It would be interesting to see the data on a longer time scale, to see how often there's an increased count with a flash at some later point, or no flash at all.
Is the implication here that the lightning is caused by an external particle? Or that the thunderstorm accelerates a particle a lot which causes the lightning?
> The Cogamo detector is a small (23 cm × 28 cm × 10 cm) and lightweight (3 kg) radiation monitor, using a CsI (Tl) scintillator (5 cm × 5 cm × 15 cm) coupled with a Silicon Photomultipliers (SiPMs) MPPC (Multi-Pixel Photon Counter) as a photo sensor (Figure 1b). The energy range for gamma-ray spectroscopy is the ∼0.2–10 MeV band. The detector acquires the energy deposit and arrival time of each radiation event and records them into a microSD card. The time tagging is performed using GPS signals. In addition, 20-s bin count rates in six energy bands for 0.2–0.5, 0.5–1, 1–2, 2–3, 3–8, and >8 MeV, GPS status, ambient temperature, humidity, and optical luminosity are recorded on the microSD card and are also sent to the web server for a quick-look purpose. An observation is started simply by connecting a GPS cable and a power cable and then turning on the power switch. Energy calibration of the Cogamo detector was performed for each file of one-hour data when analyzing, using environmental background radiation lines of 40K (1.46 MeV) and 208Tl (2.61 MeV).
Is the state of IOT such that these kinds of sensors and measurements are widespread and reasonably priced? Where can I learn more?