A solution to the ⁹B(1/2⁺) state problem using the R-matrix formalism

For the last 60 years researchers have struggled to unambiguously identify the first excited state in ⁹B. Many prior experimental and theoretical results provide conflicting answers on the expected energy that this level should possess. Within these lie a trend wherein two distinct values emerge as possible solutions to this long-standing question. This dual energy mystery has now been resolved following the identification of the 3/2⁻ ground-state ghost peak in the R-matrix spectrum of ⁹B. Re-evaluation of existing experimental data in the context of this new insight provides further proof of historical misidentification of a state at 0.8 MeV in ⁹B.