Teachers: help your kids detect cosmic rays

By Phil Plait | June 27, 2012 10:30 am

One thing I like to see is kids getting their hands on doing science. There’s something about being involved with something, actually doing it for yourself, that gives you a sense of ownership over the knowledge, makes you part of something bigger.

Here’s another chance to do that for students across the world: the ERGO telescope project. ERGO stands for "Energetic Ray Global Observatory" and the idea is to build simple cosmic-ray detectors that can be sent to classrooms all over the world. Here’s a short video describing the project:

Cosmic rays are energetic subatomic particles that come blasting in from space. They’re created by the Sun, by exploding stars, but distant galaxies… basically, by cool, interesting objects. By distributing these detectors across the world, students can share their data and come up with their own ways of examining them.

If you’re a teacher and you want your students to not just learn science, but to experience it, then this sounds like a good way to do it! They even have a simple form you can fill out to apply for a grant to get started.

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CATEGORIZED UNDER: Astronomy, Cool stuff, Science
MORE ABOUT: cosmic rays, education, ERGO

Comments (24)

  1. Jay Fox

    Video not posting even after refresh.

  2. shunt1

    How about making these available for amateur astronomers also?

    Once again, I must use my home schooling teacher certification to qualify for one of these student programs. When you get down to the actual funding, I am probably paying for it anyway.

    Outstanding idea and I fully support these simple but global projects that can provide new research data which could not be obtained in any other way.

  3. SkyGazer

    @1 Jay Fox

    This helps?

  4. shunt1

    The video was working for me just fine.

    Outstanding concept and something that I fully support.

    It is also a good training device to learn about natural background nuclear radiation, with is sadly ignored by many physics classes in today’s public schools.

  5. shunt1

    Using our knowledge of physics, electronics and software, can the followers of Bad Astronomer figure out a cheap method of obtaining the same data?

    This is the design of the ERGO imaging array:


    1) The ERGO Beta detector units are based upon simple Geiger-Müller (G-M) detector tubes excited by several hundred volts of electrical charge.

    2) We know that a simple web cam can detect high-energy charged muon particles that are easy to detect as bright pixels, that can be detected when the sensor is located in a light-proof container.

    3) Software capable of counting bright pixels at 30 frames per second from a web cam image, is rather easy to create. Reporting the events over the Internet would also be a simple software task.

    4) Any heavy metal container (such as metal pipes from the local hardware store) could be used to reduce natural background radiation events from striking the web cam sensor.

    5) The GPS coordinates (Latitude, Longitude and altitude) of the station is fixed and need only to be located once.

    6) This one still has me stumped, since they are trying to use the speed of light to triangulate the source of the muon particle events:

    Timestamp Generator Logic: In order to produce a timestamp data packet, including the local latitude, longitude, altitude, date, time, and fractions of second when the event was detected, a circuit consisting of logic circuits and microprocessors manipulates the signals and data to produce the data packet. By using a crystal oscillator to divide seconds into a billion parts (nanoseconds), the logic produces timestamps precise to within a few meters of position and to within a few tenths of a microsecond of true “GPS time.”

    Amateur scientists have always been amazingly creative. Can we invent something that would provide the same scientific quality data at a fraction of the cost?

  6. Tara Li

    How much are the bloody things? All you really need is a scintillation block, and an iPad/other tablet with GPS. Close in dark box, let app run. Question – would different phosphors in the scintillation block allow for the detection of different particles?

  7. shunt1

    Tara Li:

    This is a rather simple project (other than the timing issue) that most amatures could build at home with spare computer parts laying round.

    The Apollo crew were reporting flashes in their eyes because of the muon particles. Any CCD camera will detect these events and is often a problem with photography.

    How can we solve the timing and location problem? Two stacked cameras and have the software triangulate the direction from the two bright pixels?

    How much do these things cost? Hard to guess, but for custom hardware as shown on thier website, I would estimate a minimum of $20,000 per unit.

  8. shunt1

    Tara Li:

    I had a mental block and did not realize how simple your solution was!

    Any smart phone with GPS and camera capability would work as a muon detector.

    Just put some black tape over the camera lens and let the software run. Report the number of event counts for each GPS second obtained for that location.

  9. Tara Li

    Hadn’t really thought of the CCD itself directly as the scintillation block. Should work, though.

  10. shunt1

    Think of thousands or even millions of smart phones reporting their significant muon events once every 24 hours. Simply cover your lens and let the software run and have it report the results once a day. Super simple and the phone’s capabilities are still there for you at any time.

    Plot the global results each day and identify locations where there were sudden spikes in the muon count data. When there is a significant cosmic ray event, the muons will spread out in a cone formation from their initial impact upon Earth’s atmosphere.

    Thinks about a bolide (an especially bright meteor) and how the reports of those events are clustered around a specific location. Astronomy software is often capable of using that raw information to identify its original trajectory and orbital parameters.

    Software similar to this could be adapted for a global smart phone network to identify the origin of major cosmic ray events.

    Amateur astronomers have a long history of making complex technology simple and affordable.

    I love this global muon monitoring concept and support it fully!

  11. ACMESalesRep

    Regarding the use of a smartphone as a cosmic ray detector: There’s already an iOS app (at least; there may be others) that handles the data processing – http://wikisensor.com/ No timestamps that I can see, but if nothing else it demonstrates that the principle is sound.

  12. MadScientist

    Hey – now *that’s* fun. :) I hadn’t built a cosmic ray detector in decades. All you need is a large scintillator, a high gain photomultiplier, and a discriminator circuit.

    Although CCDs will occasionally interact with a cosmic ray, (a) the cross-sectional area is very small and (b) the device is very thin and chances of an interaction if a cosmic ray passes through are low. At the earth’s surface (and if I remember correctly) the flux is only about 4 per second per square meter. Detectors the size of CCDs will need to run for incredibly long times to gather statistically significant results; their geometry further complicates things because the orientation would be somewhat random if people walk around with it.

    Hmm .. even a Geiger-Muller tube has a very small area and since it is a gas-filled tube I doubt it is good at detecting cosmic rays at all (chances of interaction are too low). A scintillator tube wouldn’t be much better since the scintillator is small and thin. A bulk scintillator is really the best detector. I have my doubts of any real science coming out of that project.

  13. shunt1

    Give your own digital camera a test and see how many bright pixels you get with a 10 minute exposure.

    Try making your own bubble chamber and count how many events you see per minute. A super simple project that only requires some dry ice, alchohol and an aquarium.

    When I obtained some Trinitite at WSMR, that was the first thing I made when I got home. How radioactive was this stuff?

    Those of us who use digital cameras for astrophotography know all about those little spots that appear in the images we worked so hard to obtain.

    Don’t worry, I have spent 40 years specializing in exploiting people that “know” how something should be done, but can never quite make it work.

    Give me 10% of the money requested for this ERGO project and I will make it work. To insure a wide global coverage, perhaps paying each person $0.10 per day for any valid data that they download? That alone would insure coverage in many third world countries.

    I deal with results and not theory!

  14. MadScientist

    I thought I’d search for “scintillation block” since I can’t even remember where I got mine last, and this came up:


    Now there’s a serious cosmic ray detector; without looking at the documentation I would guess that 2 photomultiplier tubes are used as a “correlator” which helps sort genuine cosmic ray signals (which generate a burst of photons in the block) from detector noise or gamma or X rays which might set off a photomultiplier. I’ll even forgive the author for calling Dow Corning “Dowel Corning”.

  15. Great project! It will collect cosmic rays (events) and spread science among children. I only hope it will really reach poorer zones like Africa.

  16. SkyGazer

    Build your own “Cloud Chamber” on a shoestring:

    We did something like this in the 70´s at school, when I came with an article in “Zenit” (a dutch astronomical monthly, I still have the cover of that edition on my retina, but can´t find it online) and it is way cool.

  17. Ladies and Gentlemen,

    Thanks to all of you for your insightful comments. I love the idea of using a smartphone (maybe an old, no-longer used one) as a pixel. Here are some answers to your questions:

    1. We’re supplying the first 110 units free of charge to schools, universities, and other educational groups in order to build out our network globally. We’ll be evaluating the grant applications on the basis of interest, student involvement, and location.

    2. These units cost us about $600 in parts, and they are assembled by students here in Miami, where the project started. They have built over 100, and just a few more to go.

    3. We’re working on a third-generation pixel that would be much less expensive, and we hope to place 1,000 around the world. These units will be a mix of free, partially-underwritten, and paid. The cost will be based upon our out-of-pocket costs, since we’re not trying to make a profit. We’re starting to work on larger-scale funding to support 1,000 units.

    4. What we’d really like is a muon-specific detector (either a “resistive plate chamber” or a scintillation detector), and ideally with a coincidence circuit to eliminate background, but we haven’t figured out yet how to build one cheaply enough to be practical for this project. The idea of a webcam or smartphone camera is interesting, and we will check it out. If the CCD (or is it CMOS?) camera is sensitive enough to work with a plastic scintillator, that would be a great start.

    5. Cloud chambers are great, and we’ve used them to great advantage to show kids that cosmic rays are real, and you can actually see their traces. We’re working on a design of a demonstration chamber that doesn’t require dry ice.

    6. Finally, the ultimate goal of this project is to engage and excite students about science, and we hope to do that by involving lots of them in a real scientific study. Will we discover new science in doing so? Well, maybe not, but the history of physics is littered with people who discovered something unexpected by looking where no one else was looking.

    Thanks for all your ideas and comments!

  18. MadScientist

    Speaking of cloud chambers – the one in the San Francisco Exploratorium is awesome. I wish I had a nice big room to build one in.

  19. shunt1

    Tom Bales:

    First off, I fully support your project in every way!

    My suggestion of using smart phones was an attempt to keep things affordable and maximize the number of sensors deployed around the world.

    For a custom product with unit costs of $600 in parts and assembled by students in Miami, that is an outstanding price and much less than I had expected.

    Since I have been specializing in creating smart phone applications lately, creating an experimental application for this project will now be a personal priority.

    For calibration purposes, I would like to obtain one of your units and see if I can obtain similar results. In theory, a smart phone camera should be able to detect muons, but nobody will know for sure until it is tested and compared.

    The cloud chamber at the San Francisco Exploratorium was amazing to watch and I spent hours there while on vacation. When I needed to test how radioactive a sample of Trinitite actually was a few years later, that was my inspiration. Creating a super-saturated atmosphere is the only requirement and there are many methods available. The hot alcohol environment as shown at the Exploratorium is the best that I have ever seen.

    I will try to contact you and see if I can obtain the loan of one of your detectors.


  20. shunt1

    Well heck, someone has already done this:


    Running this application on my Android smart phone now…

  21. shunt1

    Running this application, it does seem to respond to low-level radiation sources such as a banana and a granite rock. A simple strip of black electrical tape over the camera lense is all that was required.

    This Android application may be exactly what I had in mind when I suggested using a smart phone for muon monitoring. The application cost was trivial and their website is interesting to read.


    I have no connections with this company in any way. Just wanted to see what was already available before I started to create my own muon detection software.

  22. shunt1

    How do you tell the difference between background radiation and a cosmic ray even?

    For me, it is rather simple: when the dog starts barking because my smart phone suddenly makes rapid clicking sounds!

    Wife finally asked me what my phone was doing and why it would suddenly make lots of noise that was driving the dog nuts.

    Vindication of the theory!

  23. Great idea about cellphone cameras–that one had slipped by me totally. We have been thinking about the potential of using smartphones (especially old ones no longer used), but hadn’t hit on the idea of using the built-in camera, or that someone had already done it! The detecting area is small, but what if you add a piece of plastic scintillator? The interns are going to try it this summer. Maybe there’s a way of having the camera look at two pieces of scintillator and using software to select only events that activate both scintillators–it’s all about photon sensitivity, light capture, and cleverness. Wish us luck.

    In answer to the question about terrestrial background versus cosmic muons: yes, that’s a concern. But, there are tradeoffs. In most places on earth, cosmic muons account for about half the total background radiation, so it’s like having your signal mixed up with a similar amount of noise (an engineer would say it’s a 3db loss in signal-to-noise ratio). High-altitude sites do much better, but there are some places on the planet that have notoriously high terrestrial radiation (mostly of natural origin). But, there’s something else to consider.

    We had placed the first dozen ERGO units when the accident at Fukushima occurred. At the time I thought the Geiger-Muller detector was just a stop-gap measure to get the project going until we could develop a real, affordable muon detector. All of a sudden we realized that there was yet another use for a global array of radiation detectors. It happened that none of our detectors were actually in the downwind plume at the time, we might offer something of value if such a thing occurs somewhere on earth in the future.

    There are lots of engineering tradeoffs in scientific projects, and we try to keep our eye on the ball: getting kids interested and engaged in science.


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