Existence of long-lived isomeric states in naturally-occurring   neutron-deficient Th isotopes
  Evidence for the existence of long-lived neutron-deficient isotopes has been found in a study of naturally-occurring Th using iductively coupled plasma-sector field mass spectrometry. They are interpreted as belonging to the recently discovered class of long-lived high spin super- and hyperdeformed isomers. 
A. Marinov, I. Rodushkin, Y. Kashiv, L. Halicz, I. Segal, A. Pape,   R.V. Gentry, H.W. Miller, D. Kolb and R. Brandt