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Comment by philipkglass | Hacker News Reader

The primary source is https://journals.aps.org/prc/abstract/10.1103/PhysRevC.107.0...

From the abstract:

An α-particle energy of 7750(20) keV and a half-life of 1.0 (+1.4,−0.4) ms were measured [for the new isotope astatine-190].

Now that's an unstable isotope! Makes astatine-210 look like Methuselah. Yet this is far from the fastest-decaying isotope known. Take a look at the exotic isotopes of helium:

https://en.wikipedia.org/wiki/Isotopes_of_helium#Heavier_hel...

The shortest-lived isotope is helium-10 with a half-life of 260(40) yoctoseconds.

If you don't have your exotic SI orders-of-magnitude prefixes memorized, you'll need a trip to this table to understand how incredibly short a yoctosecond is:

https://en.wikipedia.org/wiki/Orders_of_magnitude_(time)#Les...

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To make an analogy: If one yoctosecond was equivalent to the size of a human cell, one second would be the size of the milky way (in meters that is 1e-3 vs 1e21)

If there was a computer that performed one operation per nanosecond and it would take 100 years to do a particular problem, then that same problem would be solved in approximately 3 microseconds on a machine that could perform the operation every yoctosecond.

Helium-10?! I’m more amazed the half-life is nonzero.

What causes the neutron to drip instead of beta decay? Isn't the neutron bound by the strong force, just like the proton? So why would it drip, but if some of the neutrons were actually protons, now it doesn't drip?

As a coarse approximation, the more of the same type of nucleon you have on the nucleus, the more force you need to keep it from escaping, and that force comes from other nucleons. (But yes, that means turning into a proton also releases a lot of energy; that coarse approximation can't tell what happens first.)

That's why atoms stable atoms have a near balanced number of protons and neutrons, that only slowly gets pushed into the "more neutrons" direction as they grow.

The binding energy of a neutron becomes progressively weaker as the nucleus becomes more neutron rich. At the neutron drip line, the next neutron is not bound, so it's energetically possible for it to just escape.

There is also a proton drip line, where nuclei can decay from their ground state by proton emission. This would be slower as the proton must surmount a potentiel barrier, just like an escaping alpha particle does in nuclei that can undergo alpha decay.

https://en.wikipedia.org/wiki/Nuclear_drip_line

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