The interacting boson model (IBM) is a model in nuclear physics in which nucleons (protons or neutrons) pair up, essentially acting as a single particle with boson properties, with integral spin of either 2 (d-boson) or 0 (s-boson).
Both models are restricted to nuclei with even numbers of protons and neutrons.
[1]: 9 The model can be used to predict vibrational and rotational modes of non-spherical nuclei.
[1]: 6 while working at the Kernfysisch Versneller Instituut(KVI) in Groningen, Netherlands.
KVI is now property of Universitair Medisch Centrum Groningen (https://umcgresearch.org/).