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Thesis Proposal

December 1, 2022 @ 3:00 pm - 4:30 pm

“Investigation of Mg-K Abundance Anomalies in Globular Clusters Using Nuclear Resonance Fluorescence”

 

I report on the measurement of 11B and 40Ca levels between excitation energies of 8 and 9 MeV using nuclear resonance fluorescence (NRF). The experiment was carried out with nearly-monoenergetic and linearly polarized photon beams provided by the High-Intensity γ-ray Source (HIγS) facility at the Triangle Universities Nuclear Laboratory (TUNL).  States in 11B are important for calibrations of NRF measurements, while the properties of 40Ca levels impact potassium nucleosynthesis in globular clusters.

 

We also populated astrophysically important levels in 31P and 39K using the NRF technique. These levels are important for understanding the reaction rate contributions of unobserved resonances in the 30Si(p,γ)31P and 38Ar(p,γ)39K reactions, where significant uncertainties remain. These reactions are crucial for our understanding of the puzzling Mg-K anti-correlation observed in globular clusters in the Milky Way.  A scan of the astrophysically important levels was carried out by varying the incident photon beam energy, again taking advantage of the linearly polarized and nearly-monoenergetic beam characteristics at HIγS. As with the previously reported measurement of 11B and 40Ca, the linear polarization of the beam, together with the detection of the emitted γ-rays at suitable angles, will allow for the determination of excitation energies, spins and parities, which are the quantities of main interest to nuclear astrophysics. We will also obtain new nuclear structure information, e.g., γ-ray multipolarity mixing ratios and branching ratios. This experiment was carried out earlier this year and analysis of the data is in-progress.

Join Zoom Meeting

https://unc.zoom.us/j/97564617033

 

Meeting ID: 975 6461 7033

Details

Date:
December 1, 2022
Time:
3:00 pm - 4:30 pm

Venue

Phillips 258