Researcher discovers new isotope of astatine | Hacker News Reader

Researcher discovers new isotope of astatine

phys.org

45 pointswglb19 comments

The article does not mention that there are no stable isotopes of astatine, including the new discovery.

"Astatine is a fast-decaying, and therefore rare element. It has been estimated that in the Earth's crust there is no more than one tablespoon of astatine."

From the wiki:

"All of astatine's isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours."

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

The "What if" book by Randall Munroe describes astatine in very simple words: "that thing just does not want to exist".

Indeed. From Wikipedia : "A sample of the pure element has never been assembled, because any macroscopic specimen would be immediately vaporized by the heat of its radioactivity."

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...

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

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.

How is there any tablespoons in the earths crust?

It is continuously formed by the decay of Thorium and Uranium.

Here's a radioactive decay chain showing that:

https://upload.wikimedia.org/wikipedia/commons/thumb/6/65/De...

There are about 3300 bound isotopes known. It's estimated that about 7000 should exist. (Erler et al.,Nature 486 (2012) 509)

Shout out to the under-appreciated Arthur James who designed, as far as I know, the first recoil separator, for the Daresbury Nuclear Structure Facility.

Don’t know much about astatine except it’s the rarest naturally occurring element and Tom Lehrer sang about it.

https://youtu.be/AcS3NOQnsQM

The single most interesting datum to share in this story is not present: the new isotope's half-life.

Congrats to newly forged MSc Kokkonen!

Ersatz philosopher's stone: takes pure silver and transmutes it into a base metal.

Reply on news.ycombinator.com