Precision Measurements to Test the Standard Model and for Explosive Nuclear Astrophysics

Doctoral Dissertation

Abstract

Precision measurements in Nuclear Physics are an area of active study, serving as an important avenue of research for a wide variety of subfields. In this dissertation, three cases will be presented. First, the precision determination of the Ft value in T=½ mixed mirror transitions is discussed. These provide a method of determining the Vud element of the Cabbibo-Kobayashi-Masakawa matrix, and serve as an important test of its unitarity and of the electroweak sector of the Standard Model. 11C, as the lightest such β+ decay, is particularly sensitive to physics beyond the Standard Model. Thus, a new, high-precision half-life measurement was conducted using the TwinSol facility at the Nuclear Science Laboratory at the University of Notre Dame. The new half-life, t1/2=1220.27(26) s, is consistent with the previous values but significantly more precise, and the new world-average value is t1/2world=1220.41(32), a fivefold improvement over the previous value. This makes the 11C Ftmirror value the most precise of all superallowed mixed mirror values, and provides a strong impetus to the measurement of the Fermi-to-Gamow-Teller mixing ratio for the decay of 11C and thus allow the determination of Vud. Second, the Penning trap mass measurement of 56Cu using the LEBIT 9.4 T Penning trap mass spectrometer at the National Superconducting Cyclotron Laboratory at Michigan State University is presented. This mass is important for calculating reaction rates and constraining the 55Ni(p,γ)56Cu(p,γ)57Zn(β+)57Cu bypass of the 56Ni rp-process waiting point. Previous recommended mass excesses had disagreed by several hundred keV; our new measurement, ME=-38626.7(7.1) keV, resolves this discrepancy. The new calculated 55Ni(p,γ) and 56Cu(p,γ) forward and reverse rates were used to perform precision network calculations, which show the rp-process flow partially redirecting around the 56Ni waiting point. Finally, a new facility is under development at the Argonne Tandem Linac Accelerator System to allow for precision measurements necessary for the determination of the r-process path around the N=126 shell closure. The construction and commissioning of an important component of the N=126 factory, the radiofrequency quadrupole cooler-buncher, will be presented.

Attributes

Attribute NameValues
Author Adrian A. Valverde
Contributor Maxime Brodeur, Research Director
Degree Level Doctoral Dissertation
Degree Discipline Physics
Degree Name PhD
Banner Code
  • PHD-PHYS

Defense Date
  • 2018-11-12

Submission Date 2018-11-15
Record Visibility and Access Public
Content License
Departments and Units
Catalog Record

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