pub fn isotope_from_za(za: u32) -> Result<Isotope, NereidsError>Expand description
Parse ENDF ZA identifier back to an Isotope.
§Errors
Returns NereidsError::InvalidParameter when the ZA value produces
an invalid isotope (Z > A, or A == 0 — e.g. ZA = 26000 for natural
iron). Callers should propagate or handle this gracefully instead of
panicking, since real ENDF files may contain such entries.