Decay ofAt212; theBi209(α, n)At212Reaction

Abstract

${\mathrm{At}}^{212}$ was produced by the ${\mathrm{Bi}}^{209}(\alpha , n){\mathrm{At}}^{212}$ reaction by bombarding ${\mathrm{Bi}}^{209}$ with a beam of 19-MeV helium ions from the Purdue cyclotron. The ${\mathrm{At}}^{212}$ was observed to decay by alpha emission with a half-life of 0.20±0.04 sec. The kinetic energy of the alpha particles emitted in the decay was measured using Au-Si surface-barrier charged particle spectrometers. The alpha-decay energy was found to be 7.87±0.07 MeV. The relative excitation function of the ${\mathrm{Bi}}^{209}(\alpha , n){\mathrm{At}}^{212}$ reaction was also obtained in the center-of-mass energy range from 17.87 to 18.86 MeV. The hindrance factor for the ${\mathrm{At}}^{212}$ decay is calculated using the experimentally measured ${\mathrm{At}}^{212}$ alpha-decay energy.