Improved limits on Fierz Interference using asymmetry measurements from the UCNA experiment
The Ultracold Neutron Asymmetry (UCNA) experiment was designed to measure the \(\beta\)-decay asymmetry parameter, \(A_0\), for free neutron decay. In the experiment, polarized ultracold neutrons are transported into a decay trap, and their \(\beta\)-decay electrons are detected with \(\approx 4\pi\...
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Published in | arXiv.org |
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Main Authors | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
Format | Paper Journal Article |
Language | English |
Published |
Ithaca
Cornell University Library, arXiv.org
13.11.2019
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Subjects | |
Online Access | Get full text |
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Summary: | The Ultracold Neutron Asymmetry (UCNA) experiment was designed to measure the \(\beta\)-decay asymmetry parameter, \(A_0\), for free neutron decay. In the experiment, polarized ultracold neutrons are transported into a decay trap, and their \(\beta\)-decay electrons are detected with \(\approx 4\pi\) acceptance into two detector packages which provide position and energy reconstruction. The experiment also has sensitivity to \(b_{n}\), the Fierz interference term in the neutron \(\beta\)-decay rate. In this work, we determine \(b_{n}\) from the energy dependence of \(A_0\) using the data taken during the UCNA 2011-2013 run. In addition, we present the same type of analysis using the earlier 2010 \(A\) dataset. Motivated by improved statistics and comparable systematic errors compared to the 2010 data-taking run, we present a new \(b_{n}\) measurement using the weighted average of our asymmetry dataset fits, to obtain \(b_{n} = 0.066 \pm 0.041_{\text{stat}} \pm 0.024_{\text{syst}}\) which corresponds to a limit of \(-0.012 < b_{n} < 0.144\) at the 90% confidence level. |
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ISSN: | 2331-8422 |
DOI: | 10.48550/arxiv.1911.05829 |