Würzburg 2018 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 43: Neutrinophysik II

T 43.5: Vortrag

Dienstag, 20. März 2018, 17:40–17:55, Z6 - SR 2.012

Investigation of EC/ β⁺ -decays with the COBRA experiment — •Juliane Volkmer for the COBRA collaboration — TU Dresden, Institut für Kern- und Teilchenphysik, Germany

This talk’s topic will be the investigation of double beta-decay modes with the COBRA experiment and focus on EC/ β⁺ -decays. In contrast to β⁻β⁻ -decays, β⁺β⁺ -decay modes have not been observed yet, mainly due to their relatively small Q-values coupled with an extremely long half-life. Also, if the emission of two positrons is energetically possible, three different decay modes have to be dealt with: β⁺β⁺ , EC/ β⁺ and EC/EC. Having a lower half-life than β⁺β⁺ -events and creating a more characteristic signature than EC/EC-events, EC/ β⁺ -decays are the most promising of those to be detected. Measuring the half-life of 2 ν EC/ β⁺ -events would help to probe models used to calculate nuclear matrix elements. By constraining the model parameters with such experimental input it is possible to improve the half-life predictions for the standard neutrinoless double beta-decay. 0 ν EC/ β⁺ -events on the other hand are especially sensitive to the involvement of right-handed currents in the decay mechanism, thus, could help to gain a deeper understanding of the general physics involved. The COBRA demonstrator, consisting of 4×4×4 crystals of the semiconductor CdZnTe, provides three different isotopes capable of EC/ β⁺ -decays. Additionally, the experiment’s granularity greatly improves the probability to recognize the events’ characteristic decay structures. First investigations of the feasibility, the characteristic decay signature in the COBRA demonstrator and background discrimination will be presented.