Study of 14O as a test of the unitarity of the CKM matrix and the CVC hypothesis
- Univ. of California, Berkeley, CA (United States)
The study of superallowed beta decay in nuclei, in conjunction with other experiments, provide a test of the unitarity of the quark mixing matrix or CKM matrix. Nonunitarity of the CKM matrix could imply the existence of a fourth generation of quarks, right handed currents in the weak interaction, and/or new exotic fermions. Advances in radioactive beam techniques allow the creation of nearly pure samples of nuclei for beta decay studies. The subject of this thesis is the development of a radioactive beam of 14O and the study of the 14O halflife and branching ratio. The radioactive beam is produced by ionizing 12C14O radioactive gas and then accelerating with an ECR ion source. The 14O nucleus decays via superallowed beta decay with a branching ratio > 99 percent. The low Z of 14O is important for calculating reliable corrections to the beta decay that generally increase in with Z. The > 99 percent branching ratio can be established with modest precision on the complementary branching ratio.When this work began the experimentally determined CKM matrix was nonunitary by 2.5 standard deviations. Recent studies of Kaon, Hyperon, and B meson decays have been used to determine Vus and Vub matrix elements. In this work the halflife and branching ratio of 14O are measured and used to establish Vud. The unitarity of the CKM matrix is then assessed. The halflife of 14O was determined to be 70.683 ± 0.015 s and the GamowTeller branching ratio was found to be 0.643 ± 0.020 percent. Using these results the value of Vud is 0.9738 ± 0.0005. Incorporating the new values for Vus of 0.2272 ± 0.0030 and Vub of 0.0035 ± 0.0015 the squared sum of the first row of the CKM matrix is 0.9999 ± 0.0017 which is consistent with unitarity.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 840334
- Report Number(s):
- LBNL-56278; R&D Project: 460801; TRN: US0501972
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); Submitted to the University of California Berkeley, Berkeley, CA (US); PBD: 1 Jun 2004
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACCURACY
B MESONS
BETA DECAY
BRANCHING RATIO
ECR ION SOURCES
FERMIONS
HYPOTHESIS
MATRIX ELEMENTS
NUCLEI
QUARKS
UNITARITY
WEAK INTERACTIONS
SUPERALLOWED BETA DECAY HALF-LIFE OXYGEN 14 RADIOACTIVE ION BEAM