Characterization of isomers produced by the spontaneous fission of ${}^{252}$Cf with the VESPA setup

Abstract

Isomers produced by spontaneous fission of ${}^{252}$Cf have been measured with the VESPA setup, composed of LaBr${}_3$(Ce) detectors for fast $\gamma$-ray spectroscopy and an ionization chamber for detecting fission fragments. Identification of the isomers was derived from fission fragment-$\gamma$-$\gamma$ coincidences. This paper presents the half-life of 34 isomeric states measured with this setup, from less than the nanosecond up to tens of microseconds. Two of these isomers are reported for the first time, in ${}^{108}$Tc and ${}^{147}$Ce. In addition to this half-life analysis, the isomers are used to develop and test a nuclear charge calibration of the ionization chamber.