Jimmy, the Boy Genius
This page is the CodyCross answer for the clue below from California, Group 1154, Puzzle 1 (Pacific Crest Trail).
Question is: Jimmy, the Boy Genius
and the answer is: NEUTRON
Word Meaning:
NEUTRON — (particle physics) A subatomic particle forming part of the nucleus of an atom and having no charge; it is a combination of an up quark and two down quarks.
Definitions from Wiktionary.