Münster 2017 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 61: Structure and Dynamics of Nuclei X

HK 61.4: Talk

Friday, March 31, 2017, 14:45–15:00, F 33

Investigation of the spectral shape of the fourfold forbidden beta-decay of ¹¹³Cd with the COBRA experiment — •Arne Heimbold for the COBRA collaboration — TU Dresden, Institut für Kern und Teilchenphysik

Recently, the scientific discussion about the so-called quenching of the axial vector coupling constant g_A has triggered some new calculations in nuclear physics. The possibility of a quenched coupling strength has been introduced to reproduce experimental data of double beta-decay studies with theoretical models. Of special interest are highly forbidden single beta-decays since the spectral shape of the electron momentum distribution strongly depends on the effective value of g_A, but in a highly non-trivial way. The COBRA experiment at the LNGS in Italy uses CdZnTe semiconductor detectors to search for the existence of neutrinoless double beta-decay. The material acts at the same time as source of the sought double beta-decay and consists of all isotopes of Cadmium, Zinc and Tellurium according to the natural isotopic composition of those elements. One of the isotopes present is ¹¹³Cd with an abundance of about 12%. The ¹¹³Cd nucleus undergoes a fourfold forbidden, non-unique single beta-decay with a half-life of 8·10¹⁵ years, which is the most prominent signal for the COBRA demonstrator. In this talk, a first approach to compare the measured ¹¹³Cd beta spectrum of COBRA with the spectral shapes resulting from nuclear shell model calculations for various values of g_A will be presented.