Tag Archives: Cosmic-Rays

WIPAC Publishes 2nd DECO Paper

The DECO team at the Wisconsin IceCube Particle Astrophysics Center (WIPAC) has published a second paper entitled Measurement of camera image sensor depletion thickness with cosmic rays. This paper was accepted by the Journal of Instrumentation. The full text of the paper can be found here. The abstract is below:

Camera image sensors can be used to detect ionizing radiation in addition to optical photons. In particular, cosmic-ray muons are detected as long, straight tracks passing through multiple pixels. The distribution of track lengths can be related to the thickness of the active (depleted) region of the camera image sensor through the known angular distribution of muons at sea level. We use a sample of cosmic-ray muon tracks recorded by the Distributed Electronic Cosmic-ray Observatory to measure the thickness of the depletion region of the camera image sensor in a commercial smart phone, the HTC Wildfire S. The track length distribution prefers a cosmic-ray muon angular distribution over an isotropic distribution. Allowing either distribution, we measure the depletion thickness to be between 13.9~μm and 27.7~μm. The same method can be applied to additional models of image sensor. Once measured, the thickness can be used to convert track length to incident polar angle on a per-event basis. Combined with a determination of the incident azimuthal angle directly from the track orientation in the sensor plane, this enables direction reconstruction of individual cosmic-ray events.

DECO Team at WIPAC Publishes Paper

The DECO team at the Wisconsin IceCube Particle Astrophysics Center (WIPAC) has published a paper entitled Detecting particles with cell phones: the Distributed Electronic Cosmic-ray Observatory and is presenting at International Cosmic Ray Conference (ICRC) at The Hague, Netherlands on August 6, 2015 (webpage). The full paper can be found here. The abstract is below:

In 2014 the number of active cell phones worldwide for the first time surpassed the number of humans. Cell phone camera quality and onboard processing power (both CPU and GPU) continue to improve rapidly. In addition to their primary purpose of detecting photons, camera image sensors on cell phones and other ubiquitous devices such as tablets, laptops and digital cameras can detect ionizing radiation produced by cosmic rays and radioactive decays. While cosmic rays have long been understood and characterized as a nuisance in astronomical cameras, they can also be identified as a signal in idle camera image sensors. We present the Distributed Electronic Cosmic-ray Observatory (DECO), a platform for outreach and education as well as for citizen science. Consisting of an app and associated database and web site, DECO harnesses the power of distributed camera image sensors for cosmic-ray detection.