A $100 DIY muon tomographer
spectrum.ieee.org
spectrum.ieee.org
https://en.wikipedia.org/wiki/Air_shower_(physics)
And the muons produce two pulses in your detector, one when they are scattered to a stop and another when they decay. By measuring the time between the pulses you can fit the probability distribution and determine the half life of the mupn which is about 2.2 microseconds [1] And of course you can take measurements over time, at different altitudes and in different positions. If it wasn't for relativistic time dilation, muons would mostly decay high up in the atmosphere and not reach the ground.
This was one of the most popular experiments in the Physics 510 lab, which was the only class you had to take to get a Physics PhD at Cornell because it was so easy. It's also popular for high school physics for the same reason.
The dry ice experiment I did with my son was putting a dry ice pellet into a PET bottle and watching it explode maybe 40 minutes later. (A few minutes if you add cold water, goes off like a hand grenade if you use hot water) The same concept can be done with liquid nitrogen or with a mixture of chemicals that produces gas, such as aluminum foil with either a strong acid or a base. [1]
[1] https://publicintelligence.net/vermont-fusion-center-improvi...
* https://www.hackster.io/jdpetrey/muon-detector-23bb72 * https://www.madexp.it/2024/11/19/muon-and-geiger-counter/ * https://iopscience.iop.org/article/10.1088/0031-9120/50/3/31...
Pro tip - not all the SBM-20 tubes on Ebay are created equal! Some sellers will happily sell you tubes that are shorted, open, or just don't work. The better ones test their tubes.
It might take more work though. They don't say it but I believe you should try to see if other scintillator materials work. (Including PET,PSU,PES).
edit: Adding a link to a page with a list of projects on the site.
BTW, If you want to see just the DIY projects instead of all our DIY-related coverage (which can include e.g. interviews or news articles) another handy link is:
He passed away a few months after, but this sparked a smile in me.
But it is important to eventually do more rigorous checks before going for a public announcement. See Robert Wood's debunking of N-rays for what happens when one does not.
(most of the time, that was true)
Just that simple thing is so strange to me, that with a handful of components you can listen to the cosmos. I really wish science classes would have included that sort of thing.
Tuning an analog radio or TV between stations also accomplishes this in a more abstract way.
https://spaceaustralia.com/news/diy-radio-telescope-sees-fir...
https://spectrum.ieee.org/track-the-movement-of-the-milky-wa...
:)
The title here is incorrect; this is not tomography (and the OP doesn't claim it is). The article mentions tomography but what's happening here is individual measurements.
Tomography is also pretty cool, although the math is pretty painful (Terry Tao has papers on it)
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If anyone is interested, the book Parameter Estimation and Inverse Problems by Aster, Borchers, and Thurber give an easy introduction to simple tomography problems in their book. Example 1.12 in their second edition has a very basic setup. More broadly, tomography intersects with an area of study called PDE constrained optimization. Commonly, tomography problems are setup as a large optimization problem where the difference between experimental data and the output of a simulation are minimized. Generally, the simulation is parameterized on the material properties of whatever is under study and are the optimization variables. The idea is that whatever material property that produces a simulation that matches the experimental data is probably what's there. This material property could be something simple like density or something more complicated like a full elasticity tensor.
What makes this difficult, is that most good simulations come from a system of differential equations, which are infinite dimensional and not suitable for running directly in an optimization algorithm. As such, care must be taken into discretizing the system carefully, so that the optimization tool produces something reasonable and physical. Words you'll see are things like discretize-then-optimize or optimize-then-discretize. Generally speaking, the whole system works very, very poorly if one just takes an existing simulator and slaps an optimizer on it. Care must be taken to do it right.
As far as the optimizer, the scale is pretty huge. It's common to see hundreds of millions of variables if not more. In addition, the models normally need to be bounded, so there are inequalities that must be respected. For example, if something like a density isn't bounded to be positive (which is physical), then the simulator itself may diverge (a simulator here may be something like a Runge-Kutta method.)
Anyway, it's a big combination of numerical PDEs, optimization, HPC, and other tools just to get a chance to run something. Something like the detector in the article is very cool because it may be a realistic way to get data to test against for super cheap.
http://kamiokanne.uni-goettingen.de/gb/kamiokanne.htm
The FTL muons produce Cherenkov radiation in the water in the coffee cans, which is picked up by the PMTs.
Using this setup gives a much higher rate, as the surface is much larger compared to geiger tubes. Thus it's possible to quickly capture a sufficient amount of muons.
It also got me down the path of making a scintillation detector. However I've yet to find a hardware store source of scintillating material.
I kinda wanted something that didn't rely on a one-off source like asking my local uni for some scraps.
You can do very well with optically isolated pixels stacked together, followed by a common diffuser, followed by a drift gap, then 4 pmts or a position sensitive pmt with 4 cathodes. This will let you identify the struck pixel with less instrumentation. You can passively couple the outputs with resistors to get a horizontal and vertical position signals so you only need 2 data acquisition channels.
Do they sell directly to private individuals? If not, where would I get some? There are some listings on eBay but not exactly the place I prefer to shop such stuff.
The plastic scintillator is chemically just plastic so there are no safety complications shipping or receiving it. You might have more trouble getting large amounts of liquid scintillator because of the solvents.
Another thing you might consider is scintillating fiber with wavelength shifter. If you read out from both ends you can estimate position within the fiber by timing and possibly amplitude weighting.
Apart from that, yes, they are passive detectors.
But, for Russian electronics exists good rule - handle in gloves and wipe with alcohol before use (sure than properly utilize used swabs). So you will clear all dust from surface, and if you will not used to suck or crunch radio components you are in safety as from my own experience these detectors are really durable.
In the most pedantic sense, yes: electrons, magnetic fields, infrared light, etc. It's not designed to, nor is it likely to, emit any sort of ionizing radiation
> simply a passive detector
Yes, it is a passive detector
> I’m mainly worried about any potential health risks
You are bombarded with radiation constantly. If you've flown on a plane, you are exposed to several times ionizing radiation levels that you experience on the ground. If you've stepped outside and witnessed a lightning storm you have exposed yourself to high energy gamma rays and neutrons. If you've ever eaten a banana, spent the night in a strangers bed, strayed near clay river beds, entered a basement of a house, or stepped outside in sunlight you have exposed yourself to substantial increase of ionizing radiation compared to baseline.
Humans brains have an extraordinarily hard team comprehending logarithmic scales. "Safe" radiation exposure isn't "None", as that's pretty much impossible. Your body has also long ago evolved to deal with these problems and can easily handle 100x times what occurs naturally at the ground without even a single health effect.
If you want zero exposure, the only real option is to move to an undersea bubble thousands of feet below the sea, but even seawater contains radioactive ions from the metal salts dissolved in it.