Detectors in Your Pocket

The Earth is under constant bombardment. Not from aliens but from extrememly energetic electrons, protons and others sub-atomic particles. Some of these come from the Sun but the origin of many is unknown. The sources of the highest energy cosmic rays have been a subject of research for many years and has led to huge cosmic ray detectors such as the Pierre Auger Observatory and HESS which monitor the showers of particles created when a cosmic ray hits our atmosphere. However, you don't need a hugely expensive cosmic ray detector to spot cosmic rays.

Everyone who has looked at raw images from a telescope's CCD camera will probably have seen the effects of cosmic ray hits. These happen when a high-energy particle, from the shower created in the upper atmosphere, hits a pixel on the CCD detector. This tends to saturate that pixel or it can even leave a little saturated track if the particle is travelling at an acute angle to the CCD chip. You tend to see more of these cosmic ray hits the higher you are above sea level as you get closer to the top of the particle shower. Most astronomers tend to find cosmic ray hits an annoyance as they can mess up your observations and measurements. The cosmic ray hits are usually removed and then forgotten about. However, I had a sudden thought this evening; there is data there. What if you could make use of all those rejected cosmic ray hits to do some science?

Most astronomical images taken with CCDs will be saved with information such as the time, the location on the ground and the orientation of the camera on the sky. If we could extract the cosmic ray detections (and directions?) from the many astronomical telescopes in existence it would probably be possible to do something interesting depending on the density of CCD detectors in time and space.

Whilst thinking about the potential for this idea, Mark Stacey from Johannesburg pointed out that someone has already thought about it and decided to use mobile phones as a massively distributed observatory. The people behind Distributed Observatory have created an Android application that uses a phone's CMOS or CCD chip to look for cosmic ray impacts and report them back to a central site. It is a neat idea and the site FAQ says the app could be left running with your phone faced down whilst charging at night. However, Mark has tried the app out and says that it eats battery life and development seemed to stop in November last year. The project is open source though so others could always contribute towards it.

Posted in astro blog by Stuart on Monday 29th Nov 2010 (18:16 GMT) | Permalink
[an error occurred while processing this directive]
[an error occurred while processing this directive]