Exceptional points (EPs) are non-Hermitian degeneracies at which two eigenvalues and their eigenvectors coalesce, producing a defective Hamiltonian and a double pole of the $S$-matrix. Using the coupled-channel Gamow shell model with the $\ell =1$ spin-orbit strengths as control parameters, we locate and characterize EPs in ${}^6\mathrm{Li}$, ${}^7\mathrm{Li}$, ${}^7\mathrm{Be}$, and ${}^8\mathrm{Be}$, and we analyze their imprint on energies, widths, phase rigidity, spectroscopic factors, elastic cross sections, survival probabilities, and spectral functions. The signatures of the EP in scattering and time-domain observables are found to be strongly channel-dependent, and threshold effects play a decisive role in determining the accessibility of the EP in parameter space.

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• Models & methods for nuclear reactions
• Nuclear reactions
• Nuclear structure & decays
• 6 ≤ A ≤ 19
• Nuclear many-body theory
• Shell model