Can you believe it – even more fun with God’s quantum dots! 12C synthesis, near-decay-threshold resonances, the Anthropic principle, new isotopes, and action decomposition in (dual) barrier penetration

The second (nuclear) excited state in ¹²C is the gateway to the periodic table. The resonant capture of 3 alpha particles, (with ⁸Be as an intermediate) into this state with subsequent electromagnetic decay, is the accepted mechanism for generating ¹²C_gs. This nuclide then serves as the seed for the synthesis of all heavier elements. However another mechanism was proposed 55 years ago that could provide a parallel path to bound ¹²C.  During covid times we did an experiment that allows (via microscopic reversibility and a first-of-its-kind measurement) this alternative to be (finally) evaluated. The window of relevance for this alternate path is narrow.

This work is part of a program to study resonant doorways to element making via studying inverse (decay) processes. A side product of this effort is the discovery of 6 new isotopes that are so proton rich that they immediately decay by spitting out multiple protons.  How we do these experiments and our program relates to the Anthropic principle will be discussed. Finally, this program also has provided a qualifier to the worn adage in quantum mechanical barrier penetration that the action (the forbidden momentum-distance area of a potential, made unitless by dividing by hbar) cannot be decomposed to inform on the shape of the barrier traversed. The adage is wrong if two particles, correlated only by energy conservation, penetrate a common barrier.