Radiocarbon production by the gamma-ray component of supernova explosions

We selected SN1006, the brightest and closest to Earth of all supernovas historically observed, for a study of C-14 production by e(-),e(+)-bremsstrahlung cascades initiated by hard gamma rays (>10 MeV) from that event. During the cascade, bremsstrahlung energies eventually fall within a giant (n,gamma), (n,2 gamma) cross-section, peaking at 23 MeV and approaching effectively zero below 10 MeV and above 40 MeV. The neutrons are absorbed primarily in the reaction N-14(n,p)C-14 Cellulose from single-year tree rings from AD 1003 to BD 1020 was measured to determine Delta(14)C. Three years after the first visual observation of SN1006, Delta(14)C rose and remained above pre-AD 1009 values until BD 1018. Comparison of the 7 years before AD 1009 with the 9 years following show an average increase of 6.1 +/- 1.6 (s.d.)parts per thousand (significant at the 99.6% confidence level). Such a pulse of C-14 requires a total production of neutrons of 17.1 x 10(7)n cm(-2)e, implying an input of 11.3 x 10(4) ergs cm(-2)e gamma-ray energy. This requires the total supernova gamma-ray energy (>10 MeV) to have been 1 x 10(50) ergs.