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Measurement of the Neutron Beta Decay Asymmetry using Ultracold Neutrons


Mendenhall, Michael Praetorius (2014) Measurement of the Neutron Beta Decay Asymmetry using Ultracold Neutrons. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/9TS2-SG08.


The free neutron beta decay correlation A0 between neutron polarization and electron emission direction provides the strongest constraint on the ratio λ = gA/gV of the Axial-vector to Vector coupling constants in Weak decay. In conjunction with the CKM Matrix element Vud and the neutron lifetime τn, λ provides a test of Standard Model assumptions for the Weak interaction. Leading high-precision measurements of A0 and τn in the 1995-2005 time period showed discrepancies with prior measurements and Standard Model predictions for the relationship between λ, τn, and Vud. The UCNA experiment was developed to measure A0 from decay of polarized ultracold neutrons (UCN), providing a complementary determination of λ with different systematic uncertainties from prior cold neutron beam experiments. This dissertation describes analysis of the dataset collected by UCNA in 2010, with emphasis on detector response calibrations and systematics. The UCNA measurement is placed in the context of the most recent τn results and cold neutron A0 experiments.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:neutron, beta decay, weak decay, ultracold neutron
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Filippone, Bradley W.
Thesis Committee:
  • Filippone, Bradley W. (chair)
  • Golwala, Sunil
  • Vogel, Petr
  • Weinstein, Alan Jay
Defense Date:4 December 2013
Record Number:CaltechTHESIS:06042014-132823956
Persistent URL:
Mendenhall, Michael Praetorius0000-0002-5266-9940
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8479
Deposited By: Michael Mendenhall
Deposited On:06 Jun 2014 20:38
Last Modified:26 Oct 2021 18:28

Thesis Files

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Creative Commons Public Domain Dedication.


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