Subatomic physics is pretty neat stuff, but not generally considered within the reach of the home-gamer. With cavernous labs filled with racks of expensive gears and miles-wide accelerators, playing with the subatomic menagerie has been firmly in the hands of the pros for pretty much as long as the field has been in existence. But that could change with this sub-$100 DIY muon detector.
[Spencer Axani] has been fiddling with the idea of a tiny muon detector since his undergrad days. Now as an MIT doctoral candidate, he’s making that dream a reality. Muons are particles that are similar to electrons but more massive and less likely to be affected by electromagnetic fields. Muons rain down on the Earth’s surface at the rate of 10,000 per square meter every minute after being created by cosmic rays interacting with the atmosphere and are capable of penetrating deep into the planet. [Spencer]’s detector is purposely kept as low-budget as possible, using cheap plastic scintillators and solid-state photomultipliers hooked up to an Arduino. The whole project is as much STEM outreach as it is a serious scientific effort; the online paper (PDF link) stresses the mechanical and electronics skills needed to complete the build. At the $100 price point, this build is well within the means of most high school STEM programs and allows for a large, distributed array of muon detectors that has the potential for some exciting science.
We’ve covered quite a few subatomic detection projects before, from the aforementioned large-scale builds to more modest efforts. But we like this project because it has the potential to inspire a lot of citizen scientists.
Thanks for the tip, [deralchemist]
[Daniel Whiteson and Michael Mulhearn], researchers at the University of California, have come up with a novel method of detecting ultra-high energy cosmic rays (UHECR) using smartphones. UHECR are defined as having energy greater than 1018eV. They are rare and very difficult to detect with current arrays. In order to examine enough air showers to detect UHECR, more surface area is needed. Current arrays, like the Pierre Auger Observatory and AGASA, cannot get much larger without dramatically increasing cost. A similar THP Quarterfinalist project is the construction of a low-cost cosmic ray observatory, where it was mentioned that more detection area is needed in order to obtain enough data to be useful.
[Daniel Whiteson and Michael Mulhearn] and colleagues noted that smartphone cameras with CMOS sensors can detect ionizing radiation, which means they also will pick up muons and high-energy photons from cosmic rays. The ubiquitous presence of smartphones makes their collective detection of air showers and UHECR an intriguing possibility. To make all this happen, [Whiteson and Mulhearn] created a smartphone app called CRAYFIS, short for Cosmic RAYs Found In Smartphones. The app turns an idle smartphone into a cosmic ray detector. When the screen goes to sleep and the camera is face-down, CRAYFIS starts taking data from the camera. If a cosmic ray hits the CMOS sensor, the image data is stored on the smartphone along with the arrival time and the phone’s geolocation. This information is uploaded to a central server via the phone’s WiFi. The user does not have to interact with the app beyond installing it. It’s worth noting that CRAYFIS will only capture when the phone is plugged in, so no worries about dead batteries.
The goal of CRAYFIS is to have a minimum of one million smartphones running the app, with a density of 1000 smartphones per square kilometer. As an incentive, anyone whose smartphone data is used in a future scientific paper will be listed as an author. There are CRAYFIS app versions for Android and iOS platforms according to the site. CRAYFIS is still in beta, so the apps aren’t publicly available. Head over to the site to join up!
[Sebastian Tomczak] was borrowing a homeade muon detector from his friend, and managed to hook it up to his computer through an Arduino. The detector itself uses 3 fluorescent tubes to detect radiation. Three separate tubes are used in order to filter out terrestrial radiation; cosmic radiation will fall in-line with the tubes and pass through at least two of them, whereas terrestrial radiation will only hit one. There is some basic circuitry to amplify the signal and then perform the OR operation.
[Tomczak] used an Arduino to take the raw data and feed it into his computer. He then used Max/MSP to analyze the data and filter out background noise, leaving only the cosmic ray data. He didn’t mention what he was going to use the data for, though. Maybe he’ll hook it up to a synthesizer.
Related: Digital Geiger counter