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.

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!

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.

http://hotray-info.de/index.html

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.

http://www.androidzoom.com/android_applications/tools/radioactivity-counter_bizdl.html

Running this application on my Android smart phone now…

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.

Thanks;

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!

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.