Darmstadt 2016 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 26: Fundamental Symmetries

HK 26.3: Talk

Tuesday, March 15, 2016, 17:15–17:30, S1/01 A02

Measurement of the Beta Asymmetry in Neutron Beta Decay with PERKEO III — •Heiko Saul¹, Hartmut Abele¹, Dirk Dubbers², Bastian Märkisch³, Holger Mest², Alexandr Pethukov⁴, Christoph Roick³, Torsten Soldner⁴, Xiangzun Wang¹, and Dominik Werder² — ¹Atominstitut, TU Wien — ²Physikalisches Institut, Universität Heidelberg — ³Physik Department, TU München — ⁴Institut Laue-Langevin, Grenoble

Neutron beta decay is the simplest semileptonic weak decay and described accurately by the standard model using the first CKM-matrix element, Vud, and the ratio of vector and axial vector couplings, λ, as parameters. Kinematic correlation coefficients, spectra and the neutron lifetime are accessible experimantally, providing an excellent toolkit for investigating the structure of weak interaction.

Measuring the beta asymmetry A is the most precise way of determining λ, which is an important standard model parameter and necessary for the determanitaion of Vud from neutron beta decay. Moreover a precise measurement of λ allows to derive limits on non-standard-model couplings by combining with measurements of other observables.

In this talk we present the neutron decay spectrometer Perkeo III and results of the currently most precise measurement of the beta asymmetry. This measurement was carried out at the PF1B cold neutron beam line at the Institut Laue-Langevin.