Building a new Cosmic Ray Detector

For the past five years I have been fortunate to have a QuarkNet cosmic ray muon detector to use for teaching and for research with students. It’s a fun piece of real particle physics hardware, and lets me and my students go hands-on with the same muon-tracking tech we see at Fermilab, CERN, and other facilities.


QuarkNet Series 6000 CRMD. Photo: QuarkNet/Fermilab


One of the limiting factors preventing more teachers and students from using these detectors is their high cost. Without QuarkNet making these available for us to borrow, these detectors would cost us several thousand dollars each.

In the past few years I’ve seen projects to detect cosmic rays in a variety of ways, notably CRAYFIS and DECO that use the silicon imaging chip in your phone’s camera when the lens is covered or in a very dark environment. This method uses techniques similar to the silicon detectors like the pixel and strip trackers in the CMS detector at CERN. One disadvantage is the tiny area and volume of that phone sensor chip, which probably intercepts less than one muon per minute.

A more promising route for classroom use is the MIT detector, called the Cosmic Watch. This project uses inexpensive hardware to bring higher level, scintillator based cosmic ray muon detectors to teachers and students for a target price of $100, about 98% less than the absolute cost of the more capable QuarkNet detector.


Cosmic Watch CRMD. Photo:

I’m in the process of acquiring the components to build a Cosmic Watch, starting with the silicon photomultiplier from SensL in Ireland. They were kind enough to offer the preferred detector chip in small quantities to students and teachers for a discount price of $60 with available $15 shipping (no word on how long they will run this discount).


Mounted SenseL SiPM. Photo: SenseL

The MIT Cosmic Watch project website and Git repository include all of the information you need to build the detector, including source files for having the PCBs produced, dimensions for the scintillator, parts lists, and instructions for assembly and use. [2/20 Note: The newest version, which includes microSD capability and coincidence capability with two units and other revisions, can be found at the v2 Git repository here.)

Future posts here will discuss the similarities and differences between the QuarkNet and Cosmic Watch detectors, including sensitivity, data collection process, and coincidence signal detection.

Right now I’m simply going to build one for myself to experience the build and learn more about it. I’m thinking maybe local teachers would be interested in a build workshop to put together, test, and take home their own Cosmic Watch. Watch here for updates — I anticipate building this over spring break (March 17-25).


KU QuarkNet Week 2-3: Research Underway


Research Projects

The QuarkNet research assistants, all high school students or 2016 graduates, are hired to work in the Department of Physics and Astronomy. During this time, they are working with professors, graduate and undergraduate students, and others to contribute to ongoing research projects at the University.

Photos and Descriptions


Brittany and Ardrian jumped into assembling the QuarkNet Cosmic Ray Muon Detector.


Prof. Besson advises returning QuarkNet researcher Margot.


Sabrea, Asher, and Roxanna (seated) learn to operate and analyze the data from radio transmission and reception experiments.


Sabrea, Asher, and Roxanna (seated) learn to operate and analyze the data from the radio transmission and reception experiment.



Ardrian and Brittany find that commissioning a Cosmic Ray Muon Detector requires lots of testing, careful assembly, and light-tight tape.


Bennett, Margot, and Pierce collaborate on research. All three are returning QuarkNet researchers.


Within a couple of days, Ardrian and Brittany had the detector functioning and under test.



A particularly well-timed photo of Bennett and Pierce testing the revisions to their lightning detector, begun in the 2015 research season. Their device(s) are part of the TARA research at KU.


Bennett and Pierce delivered a preliminary talk about their research work and the hardware they have created to generate a trigger that includes directional and range information.


The audience at a typical research seminar includes professors, graduate and undergraduate students, and fellow QuarkNet research assistants.

QuarkNet is funded by grants from the Department of Energy and the National Science Foundation.


Makerspaces in Classrooms

I ran across a listserv post I made about a year ago, and it’s something I still think is important. This was in response to a post about converting a classroom into a STEM lab. Here’s my thoughts with only minor edits:

I would recommend perhaps trying to make that STEM lab a full

​Make it a place where your community (students AND teachers) are welcome
to come learn how to use different tools to create, make, invent, and
experience things. I have done something like this with a very small corner
of my classroom, and while the supplies and topics are limited it does give
me a place (and resources) to teach an interested student how to solder,
test electronics, and build projects.

The Maker movement is not limited to any one technology, nor is it just
STEM.​ The new acronym STEAM incorporates the arts, and I believe that
creating Makerspaces/Hackerspaces in schools could be a step toward
reuniting the creative disciplines of science, engineering, and the arts.

With a properly equipped makerspace you could then offer, or could find
people to offer, seminars on woodworking, digital circuit design, robotics,
3d design and printing, fabric crafts and working with sewing and
embroidering, incorporating microcontrollers and programming in artistic
and fashion projects, woodworking, analog circuits, clay sculpture,
microcontroller programming, game programming, jewelry, crafting musical
instruments, creating analog and digital effects circuits (pedals) for
electric guitars…obviously I can’t list everything here.

Make it a space that is open, welcoming, and useful to people interested in
science, engineering, math, and arts.  Cooperate with the art, music, tech
ed, and other teachers to try and bridge the imaginary gap between the

R​esource​s​ you might look at:


New Science Facilities

Our community recently approved a bond issue to, among other things, replace our 1960’s era science classrooms. They are poorly equipped and woefully small.

I have been keeping a “wish list” to share with the architects and engineers during our consultations between now and the end of construction. We break ground in the spring.

Physics teachers, what classroom features, bulit-ins, and equipment would you consider essential to include in a new facility? What would be on your ‘wishlist’?

Please comment below and/or reply on twitter to .

Spontaneous Calculation

Sometimes the most fun in class is when it skews off in a wildly unplanned direction.  Sometimes it’s a big skew, sometimes a little detour.

We have been studying particle physics topics in class for the past couple of weeks, including a trip to Kansas State University for a QuarkNet Master Class.  We were discussing in class that the data we used to determine the mass of the top quark came from the Tevatron at Fermilab, and that it was from a proton-antiproton collision.

Some of my students were a little incredulous at the thought of antimatter, asking “Isn’t that a science fiction thing?”  Yes, yes it is, but it is also very real.  There just isn’t much of it around, and that why exactly we have almost exclusively matter and no antimatter is a Really Good Question We Haven’t Solved Yet.  Although there is no significant amount of antimatter naturally occurring anywhere in the universe, such as no antimatter stars or planets or nebulae that we are aware of, we can manufacture it.

Manufacture it?  Yes, we can.  Particle colliders like the LHC do it all the time.  It is even created naturally in tiny quantities through certain types of radioactive decay.

“So,” one of my students asked, “how much would a pop can full of antimatter cost?”


That is a good question that deserves an answer.  After mentioning that I’m pretty sure we have not produced a pop-can full of antimatter of any kind in total, I was off to find the answer.

A Google search quickly came up with a NASA site from 1999 that quoted the cost of antihydrogen at $62.5 trillion per gram.  Sure, that’s 1999 dollars, but it will work for our purposes.

We needed a few other factors, like the density of liquid hydrogen (70.99 g/L), and the conversion from 12 fluid ounces to liters (12 Fl.oz. = 0.354882 L).  And with a quick calculation, we had our answer:  $1.57E15

That’s $1,570,000,000,000,000.

Over one and a half quadrillion dollars.

The discussion swayed to how many pop cans of antimatter you could buy if you could sell the entire planet, but by then the period was winding down and it was time to go.

It leaves me wondering…by the end of my teaching career, how far that cost for a pop-can full of antihydrogen might fall.

Finding a decent highly-portable travel laptop.

For about the last year I’ve been pondering a new laptop.  My old machine is still running quite nicely, despite it being nearly six years old.  It’s been upgraded significantly, but it is a massive block of computer compared to some of today’s options.  I’ve been attending a number of conferences and workshops involving air travel, and every ounce and square inch in my carry-on luggage makes a big difference.  The six-plus pound Toshiba was pushing the limits when cramming onto an Embraer RJ145 commuter jet.

I’m comfortable with  linux based operating systems, and by extension not too uncomfortable with the Mac’s Unix-based OSX operating system.  So when I saw a Macbook Air a few years ago, it seemed a very attractive option for travel.  However, when I specced out a decently powerful machine on Apple’s site, I always ended up somewhere between $1200 and $1700…far too much to make an impulse buy on this teacher’s salary.  I looked at the netbook options (dwindling from the marketplace, unfortunately) and low-end laptops, but it seemed that no one wanted to offer small highly-portable computers with good current processors and memory without charging an arm and a leg.  I asked around, looking for the “windows equivalent” of the Macbook Air at a sub-$1000 price.  I want small.  I want power.  I want memory.  I want inexpensive.  Nothing seemed to meet my desired specs.

Enter the Acer V5 171 series.

My new Acer laptop in a lab setting

The Acer V5 171 series is a very affordable (~$500) line of small notebooks with excellent modern processor and memory options. As shown, it is an i5-3337u with six gigs of ram for $499.

Riding the same chassis as Acer’s Chromebook offerings, this is a deceptively small machine considering the available horsepower under the hood.  I bought a mid-range model with an i5 processor, six gigs of ram, and a 500 gig 5400-rpm hard drive that sold directly from Acer for $499 (normally $579).  You can slash the price even further under $500 by opting for an i3 processor model, and for a bit more you can upgrade to an i7 model with eight gigs of ram.

Versus the Macbook Air, it is certainly a cheaper machine–by about $800 in a similar configuration.  The Macbook has advantages, such as a solid state hard drive (faster and more durable than the mechanical drive in the Acer) and a more sturdy metal chassis.  The Acer’s processor has the edge at a 1.8ghz i5-3337u vs. the Mac’s 1.3ghz i5.  The Acer also has more standard memory in the configuration I bought, 6Gb vs. 4Gb.

Either of these machines would have (in my possession) ended up with the Ubuntu linux operating system in a dual-boot configuration.  I looked at native Ubuntu laptops from System76 and ZaReason, but at the time I looked neither had a small 10″-12″ laptop at a comparable price.  If either of them had a ~12″ three-pound laptop for slightly less than the Acer Win8 machine, I would likely be typing on that now.

So far I’m quite happy with my choice.  Time will tell whether this little machine is durable and well built.

It was a little difficulty to get Windows8 and the UEFI to play nicely with Ubuntu, but a couple of hours of research online led me to working solutions.  I anticipate upgrading to a SSD in the reasonably near future, but for now I am enjoying the space available on the 500 gig drive.  There was plenty of room to shrink the Win8 partition to make space for Ubuntu.

In the next few months I’ll travel several times, and I anticipate this little laptop will be my primary computing companion.  Hopefully I’ll have good news to report on its quality and durability.