Reinessa: Catching the Ghost 1956

Nuclear & Particle Physics arc, page 175 of 193. Back to The Pixelated Physics Universe

Who they are

Reinessa hunts ghosts with a lantern made of tanks. In 1956, near a nuclear reactor, one finally showed itself.

Reinessa is a character of the Nuclear & Particle Physics arc: drawn in pixels, ruled by one piece of real physics, and never allowed to break it.

The physics

Antineutrinos from a reactor almost never interact, but now and then one hits a proton and turns it into a neutron and a positron. The detector looked for a pair of flashes: first the positron annihilating, then the neutron being captured in cadmium. The signal rose with reactor power. C. L. Cowan Jr., F. Reines and colleagues reported the detection from the Savannah River Plant in Science on 20 July 1956.

$$ \begin{gathered} \bar{\nu}_e + p \rightarrow n + e^{+} \\ \sigma \approx 6.3\times10^{-44}\ \mathrm{cm^{2}} = 6.3\times10^{-48}\ \mathrm{m^{2}} \end{gathered} $$

Symbol Meaning SI unit
$\bar{\nu}_e$ electron antineutrino 1
$p$ proton 1
$n$ neutron 1
$e^{+}$ positron 1
$\sigma$ interaction cross section m²

Honest caveat: The signal agreed (within 5 per cent) with a predicted cross section of 6.3 × 10⁻⁴⁴ cm²; that is an agreement, not a precise measurement.

Sources

Crossovers

Reinessa meets W-ZED (Weak Nuclear Force / Boson Carrier). W-ZED's weak force is why Reinessa's neutrinos so rarely interact. In 1956 she still caught one: an antineutrino hitting a proton to make a neutron and a positron.

Reinessa meets Okloa (Earth's Own Reactor). Reinessa caught antineutrinos from a man-made reactor. Okloa was a natural reactor two billion years ago, and its fission products are still in the rock.

Wear the lore

Concept keywords: Catching the Ghost 1956, Reinessa, Nuclear & Particle Physics, physics lore, Pixelated Physics