GRIFFIN

Clarifying a key step in the origin of the elements

Clarifying a key step in the origin of the elements: As reported in Physical Review C (2016) researchers using GRIFFIN have produced the highest-precision measurement ever of the half-life of cadmium-130  (¹³⁰Cd), a rare isotope that's a cornerstone for understanding cosmic element formation. Astrophysical observations are providing mounting evidence that heavy elements are forged in the merger of neutron stars. However, to understand and accurately simulate this element formation process (r-process), it's necessary to experimentally characterize the key rare isotopes involved. This is especially the case for the half-lives of isotopes with masses of about 130 since theoretical models have been tuned to reproduce the half-life of ¹³⁰Cd and then predict half-lives in the entire region. Thus, scientists used GRIFFIN to produce a ¹³⁰Cd half-life measurement three-times more precise than the previously adopted world average, a result which will help astrophysicists more clearly see our stardust origins.    

First measurement and ab initio calculation of rare excited nucleus’ energy loss

First measurement and ab initio calculation of rare excited nucleus' energy loss Using GRIFFIN, researchers confirmed the existence of a very rare case of energy loss from excited scandium-50 (⁵⁰Sc) nuclei and the TRIUMF theory group produced the first ab initio calculation of this transition rate. Nuclei in hot excited states become more stable by emitting radiation in the form of gamma (γ) rays, high energy photons, that carry away both energy and angular momentum. Usually, the gamma rays carry away one or two units of angular momentum and do not change the parity. As reported in Physical Review C (2017), scientists used the GRIFFIN spectrometer to identify the angular momentum of states in ⁵⁰Sc using γ-γ angular correlations. The existence was of a transition magnetic octupole was confirmed which carries away three units of angular momentum at once. This decay is so rare that the parent state lives for a full half a second instead of the typical one- trillionth of a second.    

Half-life measurement provides clearer view of the weak force

Half-life measurement provides clearer view of the weak force: Scientists using GRIFFIN achieved a half-life measurement of magnesium-22 (²²Mg) three times more precise than the previously adopted world average. As reported in Physical Review C (2017), this high-precision measurement provides a clearer view of the dynamics of the weak force. Precision measurements of the ft values for superallowed Fermi β-decay transitions between isobaric analog states provide fundamental tests of the Standard Model's description of electroweak interaction. These transitions provide a stringent test of the conserved vector-current (CVC) hypothesis, and in combination with other values, they also provide the most precise determination of V_ud, the most precisely determined element of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix. Researchers used a 4π proportional gas counter and the GRIFFIN spectrometer to make the ²²Mg half-life measurement, resolving a discrepancy between the two previously published ²²Mg half-life measurements.