Bulletin of the American Physical Society
2018 Annual Meeting of the Far West Section
Volume 63, Number 17
Thursday–Saturday, October 18–20, 2018; Cal State Fullerton, Fullerton, California
Session F02: Nuclear, High Energy, Accelerator and Biophysics |
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Chair: Alessandra Lanzara, University of California, Berkeley Room: Titan Student Union Gabrelino |
Saturday, October 20, 2018 2:00PM - 2:12PM |
F02.00001: Nuclear Physics with Short-Lived Beams Noraim Nunez, John W Price In nuclear physics, processes involving beams of short-lived particles are difficult to study. By using a well-understood process, such as the photoproduction of the short-lived particle, we can resolve this problem. The major difficulty lies in determining the luminosity of our measurement. The traditional method of calculating a cross section requires knowledge of the numbers of both the beam and target particles. We cannot count our beam particles directly, but we can use previous cross section measurements to estimate our beam flux. Using relativistic kinematics, we can express the beam flux in terms of our short-lived particle’s energy and lab angle. The target length, typically used in these calculations, is only valid if the beam particle is traveling along the target axis. The effective number of target particles can be determined by comparing the kinematics of our short-lived beam with the geometrical properties of the target. By multiplying the numbers of beam and target particles thus obtained to get the luminosity, we can normalize the cross section. This talk will describe the development of this new technique and discuss several applications for which it is successfully being employed. |
Saturday, October 20, 2018 2:12PM - 2:24PM |
F02.00002: Status of Ternary Fission Analysis of Neutron-induced Reactions of U238 and U235 with the NIFFTE Time Projection Chamber Alex Kemnitz, Gabriel Oman, Jennifer Lynn Klay Data from neutron-induced reactions with U238 and U235 collected with the NIFFTE time projection chamber have been analyzed to search for the rare ternary fission process in which a nucleus breaks up into three daughters rather than two. Production rates as a function of neutron energy for ternary candidates, average opening angles, and fragment energies have been investigated. Preliminary results from these studies will be presented. |
Saturday, October 20, 2018 2:24PM - 2:36PM |
F02.00003: Entanglement Entropy of Proton and Neutron Wave Functions in Atomic Nuclei Oliver Gorton, Calvin Johnson Entanglement entropy is a measure of the amount of information shared between two subsystems of a bipartite system. It can be shown that the representations of bipartite wave functions with lower entanglement entropy are dominated by fewer terms than ones with higher entanglement entropy. We compute the entanglement entropy between protons and neutrons in nuclear configuration-interaction wave functions and we find that the entanglement entropy decreases with increasing isospin. This suggests that N = Z nuclei will have even more efficient representations than N > Z nuclei in a proton-neutron factorization scheme, of the kind suggested by the singular-value-decomposition work of Papenbrock et al. Here we take a more in depth look at the entanglement entropy of |
Saturday, October 20, 2018 2:36PM - 2:48PM |
F02.00004: Testing the application of Maxwell’s equations that became special relativity Joseph A. Gilbert Although it has passed a number of different tests, the special theory of relativity may not have been a correct application of the Maxwell equations for stationary bodies, to calculate electromagnetic forces on bodies that are moving at relativistic speeds. Measurements have not yet been made to find out whether or not one or more corrective factors would be appropriate for Maxwell’s equations, as was done for Newton’s law of gravitation. For example, measurements of the Newtonian reaction known as field distortion may show that Maxwell’s equations need to be multiplied by this paper's force-factor x/c (where x = {c^{2}+v^{2}−2cvcos[180^{O}−C−Arcsin(vsinC/c)]}^{1/2}, c is the speed of light, v is the speed of a body moving at angle C away from meeting a field force head-on, and Arcsine is capitalized to denote only its principal value). If so, the definition of force F = mdv/dt = ma (where mass is a constant that is independent of velocity) would be enabled to account for the non-classical accelerations of fast-moving bodies, as follows: The force-factor x/c becomes (1−v^{}^{2}/c^{2})^{1/2} for the 90^{O} transverse forces used in oscilloscopes and particle accelerators. This result is mathematically equivalent to having mass increase by its reciprocal, the Lorentz factor 1/(1−v^{2}/c^{2})^{1/2}. |
Saturday, October 20, 2018 2:48PM - 3:00PM |
F02.00005: Modified commutation relationships via the Riemann Hypothesis Erick Robert Aiken, Michael Bishop, Douglas Alexander Singleton Current approaches to quantum gravity suggest there should be a modification of the standard quantum mechanical commutator, $[{\hat x} , {\hat p}] = i \hbar$. Typical modifications are phenomenological and designed to result in a minimal length scale. As a motivating principle for the modification of the operators and their commutators, we assume the validity of a version of the Bender-Brody-M\"uller variant of the Berry-Keating approach to the Riemann hypothesis. We arrive at a family of modifications of the position and momentum operators which lead to a minimal length scale $\Delta x_0$. Additionally, this larger family satisfies and generalizes the structure of the Bender-Brody-M\"uller approach to the Riemann hypothesis. |
Saturday, October 20, 2018 3:00PM - 3:12PM |
F02.00006: Higgsed Yang Mills Self-Interacting Dark Matter Ian W Chaffey Recent work on self-interacting dark matter (SIDM) has shown it to be a solution to many of cold dark matter's problems. We present a model for Higgsed Yang Mills SIDM resulting from a completely broken SU(2) symmetry. In this model low energy dark matter self-interactions yield an attractive Yukawa potential consistent with SIDM and an annihilation cross section which can reproduce the observed relic abundance. |
Saturday, October 20, 2018 3:12PM - 3:24PM |
F02.00007: Asymmetric Dark Matter via Unstable ``WIMPs" Michael Shamma Inspired by the similarity in their contribution to the overall energy density of matter in the universe, asymmetric dark matter (ADM) theorizes a common origin to dark and baryonic matter. Although this can be seen as a departure from historically popular weakly interacting massive particles (WIMPs), this talk demonstrates that ADM may be sourced from the decay of an unstable "WIMP". This decay is staggered into a few steps, yielding a number of interesting possibilities for asymmetry production. Among the interesting outcomes of this splitting are a UV-complete mechanism for the production of a matter asymmetry and global generalized baryon number conservation. Although this work focuses on a toy model with fermonic DM carrying a dark baryon number, similar processes involving the production of a lepton/DM asymmetry or scalar ADM are possible. |
Saturday, October 20, 2018 3:24PM - 3:36PM |
F02.00008: Cargo diffusion shortens single-kinesin runs at low viscous drag John Olan Wilson, Jing Xu, David quint, Ajay Gopinathan Molecular motors drive active transport in cells. Thermal diffusion of the cargo can impose a randomly directed, fluctuating mechanical load on the motor carrying the cargo. Recent experiments highlighted a strong asymmetry in the sensitivity of kinesin run length to load direction, raising the intriguing possibility that cargo diffusion may non-trivially influence motor run length. To test this possibility, we employed Monte Carlo simulations to evaluate the transport of cargo by a single kinesin. Our simulations included the physiologically relevant viscous drag and interrogated a large parameter space of viscosities, cargo sizes, and motor velocities that captures their respective ranges in live cells. We found that cargo diffusion shortens single-kinesin runs by imposing load in the direction of transport, which more severely impairs kinesin; this load is absent in the diffusion-free case. Viscous drag counters the diffusion-based effect, yielding an unexpected non-monotonic variation in run length. Our findings highlight the importance of cargo diffusion on single motor functions, particularly under physiological conditions. |
Saturday, October 20, 2018 3:36PM - 3:48PM |
F02.00009: Towards a realistic model of long-range plant pathogen transport by wind. Nolan Patrick P Elauria, Taeah Truong, Oleg Kogan In recent work (Phys. Rev. E 96, 022220), a model of continental-scale plant pathogen spread by wind was proposed. The model was designed to study the competition between the short-range hopping mechanism of transport due to the near-Earth turbulence, and the mechanism provided by the laminar advective currents that lie above the planetary boundary layer. The main finding was that the latter is often the dominant mechanism of propagation of invasion fronts. However, the basic model lacks sufficient biological realism, and over-predicts the speed of invasions. In the present work, we further develop the basic model in several directions. First, we add the effect of spore death due to UV exposure – a crucial factor known to phytopathologists. Second, in addition to mobile spores we now include immobile fungi, as well as the role of latent time required for new fungus to start producing spores. Our study shows that these additions allow for slowing down of the invasion speed closer to realistic values. |
Saturday, October 20, 2018 3:48PM - 4:00PM |
F02.00010: Intracellular Transport is Sensitive to Filament Polarization Bryan Maelfeyt, Ajay Gopinathan In eukaryotic cells, the intracellular transport process involves the movement of materials such as proteins, lipids, carbohydrates, and nucleic acids via phases of passive, diffusive transport and active, motor-driven transport in which molecular motors carry cargos in relatively straight lines along filaments that make up the cell’s cytoskeleton. We have developed a numerical technique to model this process where distributions of cargos are evolved in time. The distributions move via advection along filaments when designated as being on filaments and diffusion when considered off filaments. With our results, we compare first-passage times to those achieved through simulations of individual cargo movement and analyze the effects of filament lengths and polarizations on the distribution’s survival probability at given points in time. We find that for some network parameters, particularly for intermediate filament length values, cargos become more easily trapped throughout the cell which leads to relatively high survival probabilities. |
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