High-Precision Half-Life Measurement of Oxygen-14

Date
2020-09
Authors
Sharma, Shivani
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Faculty of Graduate Studies and Research, University of Regina
Abstract

Precision measurements of the ft values for Superallowed Fermi beta decays between nuclear isobaric analogue states of spin-parity Jπ= 0+, T = 1 provide fundamental tests of the electroweak interaction. These transitions are used to constrain the conserved vector current (CVC) hypothesis and provide the most precise value of Vud, the updown element of the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing matrix.

A high precision half-life measurement for one of these superallowed emitters,14O, has been performed in 2017 at the Isotope Separator and Accelerator (ISAC) facility at TRIUMF. The half-life of 14O was deduced using a 4π gas-filled proportional counter and fast tape transport system. The lightest superallowed emitters like 14O is important to probe for the non-zero scalar contributions to the nuclearβdecay. This analysis has led to a new half-life value T1/2(14O) =70627(10) ms with the precision of ±0.014%. This result is in good agreement with the previous world average, T1/2(14O) = 70619(11) ms with the precision of ±0.015 %. It is interesting to note that the new measurement is more precise than all the previous 11 measurements combined. After adding the current measurement, the new world average of 14O equals to, T1/2(14O) =70624(8) ms with the precision of ±0.011 %.

The precise half-life measurement reported is combined with the Q-value and Branching Ratio of 14O to determine the ft value. The impact of the new half-life measurement and its result on ft value will be described in detail in the thesis.

Description
A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Science in Physics, University of Regina. xii, 93 p.
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