Work

Evidence of the B 9 ( 1 / 2 + ) state in the C 12 ( p , α ) B 9 reaction

Year: 2026

Type: article

Abstract: The low-lying excitation region in B 9 has been studied through the C 12 ( p , α ) B 9 reaction with a proton beam energy of 33 MeV at the Birmingham MC40 Cyclotron. Coincident recoil α -particle and B 9 breakup products were detected by a silicon double-sided strip detector array and reconstructed to identify signatures of the elusive B 9 ( 1 / 2 + ) state. Data were collected for two distinct α -particle recoil angles, 31 ∘ and 106 ∘ , with a total beam exposure of ≈ 0.52 mC. R -matrix analysis indicates the presence of a state at E x = 1.83 ± 0.05 MeV with a width of Γ = 850 ± 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 B 9 lies at a weighted average excitation of E x = 1.84 ± 0.04 MeV with Γ = 740 ± 66 77 keV.

Source: Physical Review C

DOI: 10.1103/5rny-7zbk