The half-life of 37 K has been measured to be 1.23651(94) s, a value nearly an order of magnitude more precise than the best previously reported. The β + decay of 37 K occurs mainly via a superallowed branch to the ground-state of its T = 1/2 mirror, 37 Ar. This transition has been used recently, together with similar transitions from four other nuclei, as an alternative test of CVC and method for determining V ud , but the precision of its f t value was limited by the relatively large half-life uncertainty. Our result corrects that situation. Another motivation for improving the f t value was to determine the standard-model prediction for the β-decay correlation parameters, which will be compared to those currently being measured by the Trinat collaboration at Triumf. The new f t value, 4605(8) s, is now limited in precision by the 97.99(14)% ground-state branching ratio.
The Texas A&M University Penning Trap facility is an upcoming ion trap that will be used to search for possible scalar currents in T = 2 superallowed β-delayed proton decays, which, if found, would be an indication of physics beyond the standard model. In addition, TAMUTRAP will provide a low-energy, point-like source of ions for various other applications at the Cyclotron Institute. The experiment is centered around a unique, compensated cylindrical Penning trap that employs a specially optimized length/radius ratio in the electrode structure that is not used by any other facility. This allows the geometry to exhibit an unprecedented 90 mm free radius, which is larger than in any existing trap, while at the same time remaining a tractable overall length. The trap geometry was designed from first principles to be suitable for a wide range of nuclear physics experiments. In particular, the electrode structure is both "tunable" and "orthogonalized", which allows for a near quadrupole electric field at the trap center, a feature necessary for performing precision mass measurements. β + 0 + , T = 2 γ p 0 + , T = 2
Previous work has quantified the degree of neutron-proton equilibration in heavy-ion nuclear collisions by observing the convergence of isospin observables (such as the isoscaling parameter α) to an expected value based on similar symmetric reaction systems. We present a new signature of equilibration: the convergence of the isospin asymmetry (as quantified by three isoscaling metrics) of two mirror asymmetric reaction systems towards each other rather than a pre-defined point. For the reactions of 35 MeV/u 64,70 Zn+ 64,70 Zn and 64 Zn, 64 Ni+ 64 Zn, 64 Ni the neutron-proton equilibration was found to be approximately 80%, and this result is compared directly to previous work.
We measured the isotope shifts between Rb isotopes (86m, 86g, 81) and 87 Rb for the 5S 1/2 to 5D 5/2 transition using the Doppler-free two-photon transition technique. By making a King plot, the difference between the specific mass shift constants of the 5S 1/2 and 5D 5/2 states is deduced to be 77(33) GHz amu. In addition, we measured the hyperfine constants of the 5D 5/2 states in those three Rb isotopes, and we have determined an improved ground state hyperfine constant in 86m Rb, A(5S 1/2 ) = 563.04(5) MHz.
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