Beta-decay total absorption measurements for nuclear technology and astrophysics

Abstract. An accurate determination of the beta-decay intensity distribution is of importance for basic nuclear physics but also in the fields of reactor technology, astrophysics and fundamental interactions. Most of present information comes from experiments performed with high resolution low efficiency Ge γ-ray spectroscopy, which fails to locate the beta intensity at high excitation energies in complex decays. The total absorption spectroscopy technique with large 4π scintillation detectors can give the correct answer but requires an involved procedure in order to extract the information. Recent work on the systematization of the analysis methods and on the evaluation of the associated systematic uncertainties shows that reliable beta strength distributions can indeed be obtained. 1 Importance of beta-decay intensity and strength distribution measurements An accurate determination of the distribution of the β-decay probability as a function of the energy of the excited level in the daughter nucleus is of importance in basic nuclear physics but also in other fields [1]. In basic nuclear physics the β-strength distribution can be utilised as a tool for nuclear structure studies since it is sensitive to the overlap of the initial and final wave functions and the basic interaction is well understood. The relation of the β-intensity Iβ into a level of energy Ex with the β-strength S β and the squared theoretical matrix elements B is given by: S β(Ex)