Very shortly summarized, only if the particle is faster than the local speed of light, you get constructive interference between many atoms that were polarized by the moving particle.
For a slower than light particle, you also get emission, but it is completely random and thus does not give the well defined emission in a cone of Cherenkov radiation.
For a faster than light particle, the spherical suddenly line up to form a cone:
Neutrinos are neutral particles, they do not carry an electromagnetic charge. They thus do not cause any Cherenkov light themselves.
What Neutrino detector measure is the Cherenkov light emitted by secondary particles that are created when a Neutrino interacts with the matter inside the detector.
E.g. a muon Neutrino reacts with a water molecule producing a muon, which is a charged particle and thus emits Cherenkov light.
The article has a section about what it can be used for, but only mentions the uses of the IAEA.
Of course I am biased because I work in the field, but the by far most wide reaching application of Cherenkov radiation is in the detection of high energy particles, particularly in astrophysics.
- Imaging Atmospheric Cherenkov telescopes detect the Cherenkov radiation emmited in the atmosphere when a high energy cosmic ray or gamma ray creates an air shower
- Water Cherenkov Detectors detect Cherenkov light when the secondary particles of these air showers reach water tanks on the ground
- Neutrino telescopes like kamiokande, Icecube and km3net detect Cherenkov radiation in water or ice produced by secondary particles produced by the rare interactions of Neutrinos in their detector volumes
Modern, high energy astrophysics is all about detecting different kinds of Cherenkov radiation and then reconstructing the original particle properties.
As an aside, open core research reactors that glow are a very cool marketing tool for STEM. I went to a college with an open-core TRIGA run by undergraduates that loved to pulse it. It never failed to awe high school students.
Unix time does not count elapsed seconds in real time since 1970-01-01T00:00:00, this is a common misconception.
Unix time assumes a fixed number of seconds per day. 86400. If a leap second is inserted, either end of June or end of December, the day is 86401 seconds long.
There are different implementations for how your Unix time will behave 24 hours before to 24 hours after the leap second. A timestamp might just repeat during the leap second or the system changes the length of a second in a time range around the leap second introduction to make up the difference. This is called smearing.
A simple example is the elapsed time between these two timestamps:
2016-12-31 23:59:50
2017-01-01 00:00:10
Unix time differs by 20 seconds (assuming the system/library doesn't use smearing). But actually elapsed time is 21 seconds, since
2016-12-31 23:59:60
was the last added leap second. This timestamp cannot be represented by Unix time (again assuming no smearing, with smearing you could).
Only the charged particle that induces the emission travels faster than the local speed of light.
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