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The 25 Al(p,γ) 26 Si reaction plays a key role in accurately modeling and understanding the nucleosynthesis of the long-lived radioisotope 26 Al observed throughout the Galaxy by γ-ray telescopes via the detection of its 1.809 MeV γ-ray line. The 25 Al(p,γ) 26 Si reaction is responsible for redirecting the flux of nuclear material away from the ground state of the long-lived radioisotope 26 Al ( 26 Al g ) in favor of its short-lived isomer ( 26 Al m ) which bypasses the emission of the 1.809 MeV γ-ray, but is observed in, for example, an excess of the isotopic abundance of 26 Mg in meteorites. Uncertainties in the 25 Al(p,γ) 26 Si reaction rate are dominated by the nuclear properties of low-lying proton-unbound states in 26 Si. A high-sensitivity spectroscopic study of 26 Si was performed at the John D. Fox Accelerator Laboratory at Florida State University, using a neutron/γ-ray coincidence measurement with the 24 Mg( 3 He,nγ) 26 Si reaction. The present measurement solves previous discrepancies in the existence and location of the relevant resonances in 26 Si. Furthermore, the high sensitivity of the study allowed for a direct estimate of the 3 + 3 γ-partial width. The present experimental information combined with previous works provide an updated rate of the 25 Al(p,γ) 26 Si reaction at nova temperatures.

We describe a methodology for constructing tabular potentials of supertoroids with short-range interactions, which requires the calculation of the volume of overlap of these shapes for many relative positions and orientations. Recent advances in the synthesis of anisotropic colloids have made experimental realizations of such particles feasible and have increased the practical impact of fundamental simulation studies of these families of shapes. This extends our recent work on superquadric potentials to now include a family of ring-like shapes with a hole in the middle. Along with the addition of supertoroids, the ability to make tables for nonidentical particles and particle pairs with multiple, disconnected overlap volumes was added. Using newly developed extensions to a previously published algorithm, we produced tabular potentials for all of these new cases. The algorithmic developments in this work will enable Monte Carlo simulations of a wider variety of shapes to predict thermodynamic properties over a range of conditions.

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