In the paper below, Lebedev et al. (2000) provide support for nucleon clusters (alpha, d, t), which are predicted by the Brightsen Model.

Supermultiplet Symmetry and Near-Threshold Levels in Systems Featuring Two or Three Extremely Light Clusters

Physics of the Atomic Nuclei, Vol. 63, 2000, pp. 195-203

Lebedev, V. M.^a; Neudatchin, V. G.^a; Sakharuk, A. A.^b

a. Institute of Nuclear Physics, Moscow State University, Vorob’evy gory, Moscow, 119899 Russia
b. Brest State University, Brest, Belarus

On the basis of the supermultiplet potential model for the interaction of extremely light clusters (formalism of Young diagrams), it is explained why the d + t system does not feature a (1/2)⁺ (L = 0) level allied to (3/2)⁺ (L = 0) thermonuclear resonance. By using known data on the quasielastic knockout of nucleons from the inner 1s shell of light nuclei, a systematics of near-threshold states in the t + d + d, t + t + d, and t + t + t systems is constructed in terms of excited Young diagrams like \{f\} = \{322\}. The emergence of similar states in going over from the d + d and t + t systems (which feature no such states) to the alpha + d + d, alpha + t + d, and alpha + t + t systems (where they appear owing to the binding effect of the alpha particle) is discussed. The three-cluster states being considered may be important not only for nuclear physics proper but also for nuclear astrophysics. © 2000 MAIK “Nauka / Interperiodica”.