The low-lying excitation region in ${}^9\mathrm{B}$ has been studied through the ${}^{12}\mathrm{C}(p,\alpha ){}^9\mathrm{B}$ reaction with a proton beam energy of 33 MeV at the Birmingham MC40 Cyclotron. Coincident recoil $\alpha$-particle and ${}^9\mathrm{B}$ breakup products were detected by a silicon double-sided strip detector array and reconstructed to identify signatures of the elusive ${}^9\mathrm{B}(1/2^{+})$ state. Data were collected for two distinct $\alpha$-particle recoil angles, ${31}^{\circ }$ and ${106}^{\circ }$, with a total beam exposure of $\approx 0.52$ mC. $R$-matrix analysis indicates the presence of a state at $E_{\mathrm{x}}=1.83\pm 0.05$ MeV with a width of $\mathrm{\Gamma }=850{\pm }_{88}^{110}$ keV with a confidence level of 99.1% and no signature of any lower-lying state. This result is shown to be consistent with four previous measurements over the last 25 years, signifying strong evidence that the first excited state in ${}^9\mathrm{B}$ lies at a weighted average excitation of $E_{\mathrm{x}}=1.84\pm 0.04$ MeV with $\mathrm{\Gamma }=740{\pm }_{66}^{77}$ keV.

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• Coulomb energies & analogue states
• Energy levels
• Few-body systems
• Nuclear spin & parity
• Nuclear structure & decays
• Transfer reactions
• 6 ≤ A ≤ 19