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

<p>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 <em>T=1/2</em> mixed mirror transitions is discussed. These provide a method of determining the <em>V</em>ud 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 <em>TwinSol</em> 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 <em>rp</em>-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 <em>rp</em>-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 <em>r</em>-process path around the <em>N=126</em> shell closure. The construction and commissioning of an important component of the <em>N=126</em> factory, the radiofrequency quadrupole cooler-buncher, will be presented. <br></p>