Measurement of isomeric-yield ratios for the Au-197(gamma,n)Au-196m,Au-g reactions induced by bremsstrahlung

Abstract

We measured isomeric-yield ratios for the Au-197(gamma,n)Au-196m,Au-g reactions with bremsstrahlung energies of 50-, 60-, 70- MeV, and 2.5-GeV at the two different electron linac of the Pohang accelerator laboratory by using the activation method. The photons were produced when a pulsed electron beam hit a thin tungsten target. The well-known photoactivation method was used and hence the induced activities in the irradiated foils were measured with the high-resolution gamma-ray spectrometric system consisting of lithium drifted high-purity Germanium detector and a multichannel analyzer. The measured isomeric-yield ratios for the Au-197(gamma,n)Au-196m,Au-g reactions were (4.95 +/- A 0.51) x 10(-4), (5.72 +/- A 0.72) x 10(-4), (6.03 +/- A 0.50) x 10(-4), and (9.27 +/- A 0.83) x 10(-4) for 50-, 60-, 70-MeV, and 2.5-GeV bremsstrahlung energies, respectively. The present results measured with the bremsstrahlung energy higher than 60-MeV are the first measurement.