Cosmic Ray CCD video.

Nice video explaining how CCDs capture cosmic rays…

Its ‘just’ explaining a website, but its a nice easy 6 mins. The CCD in the experiment described is much thicker than an iPhone camera, so on the iPhone camera straight tracks are rarer, and cosmic rays are also often straight through – just dots.

How would you classify these?


  1. Xiaochao Zheng says:

    Hi, I just downloaded the app yesterday and I was so eager to try it that I used it without a shutter. I wonder if you can post some typical pictures for, e.g., events triggered by visible photons and cosmic rays. I got some colorful “painting”-like which I believe is due to visible light, some with only one dot on a long rectangular black background, some with two dots on a more square background, etc, but none with a straight track. I wonder if the single and the double dots are also cosmic rays?


    • pa-admin says:

      Without tape or some other blocker you are going to see weird little coloured regions, nothing will work right. The site has many images of cosmic rays as collected on an iPhone 5 and a few from an iPhone 6.

    • pa-admin says:

      Cosmic rays are energetic particles (like protons, etc) coming from outer space. They hit the earth’s atmosphere and create lots of other particles (i.e. muons, electrons) called a shower. These particles hit the camera detector (CCD) in your iPhone, and make a streak or a bright dot. Since the camera is dark, you would expect to see nothing in the camera. These streaks are particles from outer space hitting your phone’s camera. These particles also hit you at a rate of 100 per second.

    • pa-admin says:

      The b indicates how many interesting blocks were found on the captured frame. Blocks are 20 pixels on a side for 400 pixels each. On a captured frame that is 1000×1500 pixels, there are 1.5 million pixels which makes for 3750 blocks. The Cosmic Ray app studies 3750 blocks about 4 times a second, and finds one block every minute or so that is interesting. That’s an event. Events have 1,2,3…50 or more blocks lit up. Different phones capture at different rates.

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