Fine structure in proton radioactivity: An accurate tool to ascertain the breaking of axial symmetry in Tm-145

With a proper formalism for proton emission from triaxially deformed nuclei, we perform exact calculations of decay widths for the decays to ground and first excited 2+ states in the daughter nucleus. Our results for rotational spectrum, decay width and fine structure in the case of the nucleus 145Tm lead for the first time to an accurate identification of triaxial deformation using proton emission. This work also puts in evidence the advantage of proton emission over the conventional probes to study nuclear structure at the proton drip-line.