Hat-tip to Pixy Misa, here is a helium atom with an antiproton in its electron-shell. What the...
First I had to figure out what this monster even is. If you run an antiproton at a proton they both go boom. Helium has two protons, with a neutron or two sealing them together. But apparently the He-4 nucleus doesn't get mutually exploded when it meets an antiproton; these two agree to behave like Hadrian and Antinous, with the helium simply trapping the antiproton into its lower "orbit". The outer shell remains an electron as usual. UPDATE 4/1: So, like muonic helium, but longer-lived. Chemical pseudohydrogen.
Contrast hypertriton, where some exotic is in the nucleus itself; this one is in the shell.
But this chimaerical atom(?) is not the discovery. Anna Sótér, and others like Masaki Hori, have been working with this since 2013. The discovery is the spectroscopy - the wavelength of light (i.e. colour) that gets emitted when that outer electron is pushed to the next higher state, and then snaps back in again. In a gas the atoms don't do this all at once, smudging the colour. Usually they need as few helium atoms as possible. Sótér says that she's picked out a near-perfect spectrum from a hybrid in a superfluid bath of normal He-4 at 2.2 K.
The researchers couldn't believe any of the above either, only publishing yesterday after years of re-checking.
Hori and Sótér (in that order), with most the same team, have already pushed pions (easy enough to make) into these shells (again: around their nuclei). Kaons are next. We're told that all this work can constrain fundamental constants better.
USE 3/12/22: Rockets.
No comments:
Post a Comment