Application of low energy photon spectroscopy in isomer production of Hf, W, Ir, Pt, Au and Hg using (gamma,gamma ') reactions

In the present work we present results of activation analysis of various he avy metals using bremsstrahlung gammas to create short lived nuclear isomer s. The method uses inelastic gamma scattering on natural samples of I-If, W , Ir, Pt, Au, and Hg to produce the isomers Hf-179m, W-183m, Ir-191m, Pt-19 5m, Au-197m, and Hg-199m. For isomer detection, a comparison is made betwee n the minimum detection limit achievable using either isomeric gammas or th e characteristic X-rays which follow internal conversion. This latter mecha nism has the bulk of the decay probability for most of the nuclei studied. An election linac was used to produce the bremsstrahlung, with electron ene rgies between 6 and 8 MeV being optimal. Interferences were investigated an d optimal irradiation and counting times were determined using predominantl y low energy photon spectroscopy. A linear electron accelerator producing b remsstrahlung radiation with a maximum quanta of 6-8 MeV has proven to be o ptimal for the isomeric excitation. (C) 1999 Elsevier Science B.V. All righ ts reserved.