[cshimmin]

True, but the hot pixels you see in the CCD isn't from bit flips. Rather the CCD is properly doing its job of collecting electrons. It's just that spurious electrons are being produced by the cosmic rays' ionization trail (as opposed to photoelectron in normal operation).

[anamexis]

What's the difference? Aren't bit flips also just spurious electrons being produced by the cosmic rays' ionization trail?

[akiselev]

It’s an excitation of the sensor. It may be interpreted somewhat like a bit flip when converted to an image, but it’s normal for image sensors to experience a lot of noise, going back to the days of film. It may just be eliminated by the denoising algorithm like most spurious electrons/photons.

[godelski]

Bitflip is when a high energy particle changes the state of a memory address or signal in a wire.

Hot pixels are when the CCD (camera sensor) achieves its max level and becomes bright. Pixel overloaded (should also result in spillover).

Difference is really just what part of the system receives the energy. For example, you can overload a pixel with a laser, but you also should get spillover. Bit flips tend to be more localized, affecting only one part. In reality, the difference doesn't matter too much, as long as we're keeping our discussion to cosmic events. But also note that images experience a lot of (non-gaussian) noise and plenty of this is from cosmic excitation as well as from other natural and man made sources. Just the levels are a lot lower and unlikely to result in a bitflip (which is a pretty high energy event).

[cshimmin]

Pretty much this. But the point is that a bitflip would be like, your CCD was supposed to read out value 0b00000 = 0 but due to cosmic ray interference, it read out 0b10000 = 16 instead.

Instead, what's happening in GGP's experiment is that actual electrons, created in the bulk of the active silicon region by a passing cosmic ray, are getting detected by the CCD, and it will (correctly) read out some value between 00000 and 11111, depending on how many electrons it saw. In principle you can actually make a histogram of these readout values and observe the Bethe-Bloch distribution of energy loss for ionizing particles through the (very thin) bulk of silicon! On the other hand, random bit flips (which are much rarer!) would just give you a random distribution of the numbers {00000, 00001, 00010, 00100, 01000, 10000}.