Aachen 2019 – scientific programme

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T: Fachverband Teilchenphysik

T 56: Neutrino-Detektoren II

T 56.2: Talk

Wednesday, March 27, 2019, 16:15–16:30, S07

Investigation of g_A quenching using the COBRA demonstrator to study the β-spectrum shape of ¹¹³Cd — •Stefan Zatschler for the COBRA collaboration — TU Dresden, Institut für Kern- und Teilchenphysik

The COBRA experiment is dedicated to the search for the hypothesized neutrinoless double β-decay using CdZnTe semiconductor detectors. Located at the underground facility LNGS in Italy it is shielded from cosmic rays which allows for the investigation of ultra-rare nuclear decays. Besides the examination of naturally present ββ-isotopes it also allows for the study of the fourfold forbidden non-unique β-decay of ¹¹³Cd.

Nuclear model calculations predict that the spectral shape of the electron momentum distribution of highly forbidden β-decays, such as ¹¹³Cd with a Q-value of about 320 keV and a half-life of 8· 10¹⁵ yrs, is sensitive to the effective value of the axial-vector coupling strength g_A involved in nuclear processes. In order to confirm a quenching of g_A, which is proposed to reproduce half-life measurements with the help of nuclear models, the COBRA demonstrator was optimized for a dedicated ¹¹³Cd low-threshold run.

This talk will cover the optimization of the COBRA demonstrator, an overview of the data-taking as well as the statistical analysis to extract effective values of g_A for several considered theory frameworks.

COBRA is funded by the German Research Foundation DFG.