SuperNEMO is a double- β decay experiment, which will employ the successful tracker–calorimeter technique used in the recently completed NEMO-3 experiment. SuperNEMO will implement 100 kg of double- β decay isotope, reaching a sensitivity to the neutrinoless double- β decay ( 0νββ ) half-life of the order of 1026 yr, corresponding to a Majorana neutrino mass of 50–100 meV. One of the main goals and challenges of the SuperNEMO detector development programme has been to reach a calorimeter energy resolution, ΔE∕E , around 3%∕E(MeV) σ , or 7%∕E(MeV) FWHM (full width at half maximum), using a calorimeter composed of large volume plastic scintillator blocks coupled to photomultiplier tubes. We describe the R&D; programme and the final design of ...