Frankfurt 2014 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 28: Astroteilchenphysik

HK 28.6: Vortrag

Dienstag, 18. März 2014, 18:30–18:45, HZ 9

Measurement of the beta asymmetry in neutron beta decay — •H. Saul¹, H. Abele², D. Dubbers³, B. Märkisch³, H. Mest³, A. Pethoukov⁴, N. Rebrova³, C. Roick³, T. Soldner⁴, X. Wang², and D. Werder³ — ¹FRM II, Technische Universität München, Garching, Germany — ²Atominstitut, Technische Universität Wien, Wien, Austria — ³Physikalisches Institut, Universität Heidelberg, Heidelberg, Germany — ⁴Institut Laue-Langevin, Grenoble, France

Neutron beta decay is the simplest semi-leptonic weak decay and described accurately by the standard model using the first CKM-matrix element and the ratio of vector and axial vector couplings, λ. With more than a dozen observables it is a sensitive probe for investigating the nature of weak interaction and to search for physics beyond the standard model. In the past, measuring the beta asymmetry A in polarized neutron decay has been the most precise way of determining λ and nowadays it allows - together with other observables - to derive limits on non-standard model interactions, such as scalar and tensor couplings. The neutron decay spectrometer Perkeo III was installed at the PF1B cold neutron beam site at the Institut Laue-Langevin to measure the beta asymmetry. By using a pulsed beam combined with an improved detector design a significant reduction of several systematic uncertainties has been achieved compared to the predecessor, Perkeo II.

In this talk recent results of the measurements with Perkeo III will be presented. In particular, we show the energy distribution of the electrons together with the calibration tools for the detectors.