From Spinach Documentation Wiki
Database of multiplicities and magnetogyric ratios for stable and long-lived particles, including spin zero.
name - the name of the isotope, e.g. '195Pt'; high-spin electrons may be requested by supplying 'E' followed by multiplicity: 'E3' would request a spin-1 electron and so forth. Special cases: 'G' - ghost spin: gamma=0, mult=1 'N' - neutron 'M' - muon 'P' - proton
gamma - magnetogyric ratio, rad/(s*Tesla) multiplicity - spin multiplicity of the particle
Data with no source specified was sourced from Google and should be double-checked before running production calculations.