|2019 Spring Graduate Colloquium Series|
Search for Deviations from the Inverse Square Law of Gravity at Nanometer Range Using a Pulsed Neutron Beam
Many theories that attempt to combine gravity and quantum mechanics introduce compact dimensions to solve the hierarchy problem. Compact extra dimensions predict that gravity should follow the Yukawa Potential at short distances. This means deviations from the inverse square law could be evidence for compact extra dimensions and therefore these theories. This talk will examine several different experiments searching for deviations from the inverse square law, focusing on one of the most recent experiments which tested the law at nanometer range using a pulsed neutron beam. This experiment set a new upper bound to the interaction strength at nm length.
C.C. Haddock, et. al., Phys. Rev. D 97, 062002 (2018)
Multi-fluid Approach to Modeling Waves in
Partially Ionized Plasmas
Plasma heating due to ion-neutral collisions is one mechanism by which Alfvénic waves are thought to transport large amounts of energy from the photosphere to higher levels of the solar atmosphere. Likewise, nonlinear magnetohydrodynamic (MHD) waves have also been suggested as having a role in heating the solar atmosphere. Components of the partially ionized plasma in the solar environment are not strongly coupled at frequencies larger than the ion-neutral collision frequencies, which means that we must not treat the plasma as a single fluid when investigating these processes. Here we will discuss the results of a numerical simulation investigating multi-fluid modeling of high-frequency waves in non-linear, partially ionized plasma as found in quiescent solar prominences.
Martinez-Gomez, David, et al. Multi-Fluid Approach to High-Frequency Waves in Plasmas. III. Nonlinear Regime and Plasma Heating. The Astrophysical Journal, vol. 856, no. 1, 2018, p. 16., doi:10.3847/1538-4357/aab156.
For more information contact: Dr. Kenneth Park 254-710-2282