Measurement of the Isomeric Yield Ratio of Zirconium-89m from Zirconium-88 Thermal Neutron Absorption*

The thermal neutron capture cross section of zirconium-88 has recently been measured at the remarkably high level of 800,000 barns. Measurement of this cross section via reactor irradiation and product analysis requires correction for the decay path of zirconium-89 through its metastable state, which resides at 588keV above the ground state with a half-life of 4.2 minutes. We present a precise measurement of the rate at which the metastable state is populated (the isomeric yield ratio), by the method of reactor irradiation and HPGe analysis. This experiment was conducted at the TRIGA Mark II research reactor at University of Texas at Austin. We present a result of 74.9+-0.6% for the isomeric yield ratio.