Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 5 of 5
Full-Text Articles in Physical Sciences and Mathematics
Spatio-Temporal Cluster Detection And Local Moran Statistics Of Point Processes, Jennifer L. Matthews
Spatio-Temporal Cluster Detection And Local Moran Statistics Of Point Processes, Jennifer L. Matthews
Mathematics & Statistics Theses & Dissertations
Moran's index is a statistic that measures spatial dependence, quantifying the degree of dispersion or clustering of point processes and events in some location/area. Recognizing that a single Moran's index may not give a sufficient summary of the spatial autocorrelation measure, a local indicator of spatial association (LISA) has gained popularity. Accordingly, we propose extending LISAs to time after partitioning the area and computing a Moran-type statistic for each subarea. Patterns between the local neighbors are unveiled that would not otherwise be apparent. We consider the measures of Moran statistics while incorporating a time factor under simulated multilevel Palm distribution, …
Electron-Ion Collider Performance Studies With Beam Synchronization Via Gear-Change, I. Neththikumara, Geoffrey A. Krafft, Y. Roblin, Balša Terzić
Electron-Ion Collider Performance Studies With Beam Synchronization Via Gear-Change, I. Neththikumara, Geoffrey A. Krafft, Y. Roblin, Balša Terzić
Physics Faculty Publications
Beam synchronization of the future electron-ion collider (EIC) is studied with introducing different bunch numbers in the two colliding beams. This allows non-pairwise collisions between the bunches of the two beams and is known as "gear-change", whereby one bunch of the first beam collides with all other bunches of the second beam, one at a time. Here we report on the study of how the beam dynamics of the Jefferson Lab Electron Ion collider concept is affected by the gear change. For this study, we use the new GPU-based code (GHOST). It features symplectic one-turn maps for particle tracking and …
Beam-Beam Effect: Crab Dynamics Calculation In Jleic, He Huang, Vasiliy Morozov, Yves Roblin, Amy Sy, Fanglei Lin, Yuhong Zhang, Balša Terzić, Salvador Sosa, Isurumali Neththikumara
Beam-Beam Effect: Crab Dynamics Calculation In Jleic, He Huang, Vasiliy Morozov, Yves Roblin, Amy Sy, Fanglei Lin, Yuhong Zhang, Balša Terzić, Salvador Sosa, Isurumali Neththikumara
Physics Faculty Publications
The electron and ion beams of a future Electron Ion Collider (EIC) must collide at an angle for detection, machine and engineering design reasons. To avoid associated luminosity reduction, a local crabbing scheme is used where each beam is crabbed before collision and de-crabbed after collision. The crab crossing scheme then provides a head-on collision for beams with a non-zero crossing angle. We develop a framework for accurate simulation of crabbing dynamics with beam-beam effects by combining symplectic particle tracking codes with a beam-beam model based on the Bassetti-Erskine analytic solution. We present simulation results using our implementation of such …
Equilibria And Synchrotron Stability In Two Energy Storage Rings, B. Dhital, Jean R. Delayen, Y. S. Derbenev, D. Douglas, Geoffrey A. Krafft, F. Lin, B. Morozov, Y. Zhang
Equilibria And Synchrotron Stability In Two Energy Storage Rings, B. Dhital, Jean R. Delayen, Y. S. Derbenev, D. Douglas, Geoffrey A. Krafft, F. Lin, B. Morozov, Y. Zhang
Physics Faculty Publications
In a dual energy storage ring, the electron beam passes through two loops at markedly different energies E_{L}, and E_{H}, i.e., energies for low energy loop and high energy loop respectively. These loops use a common beamline where a superconducting linac at first accelerates the beam from EL to EH and then decelerates the beam from EH to EL in the next pass. There are two basic solutions to the equilibrium problems possible, i.e., ’Storage Ring’ (SR) equilibrium and ’Energy Recovery Linac’ (ERL) equilibrium. SR equilibrium mode more resembles the usual single loop storage ring with strong synchrotron motion and …
Instability Of Flux Flow And Production Of Vortex-Antivortex Pairs By Current-Driven Josephson Vortices In Layered Superconductors, Ahmad Sheikhzada, Alex Gurevich
Instability Of Flux Flow And Production Of Vortex-Antivortex Pairs By Current-Driven Josephson Vortices In Layered Superconductors, Ahmad Sheikhzada, Alex Gurevich
Physics Faculty Publications
We report numerical simulations of the nonlinear dynamics of Josephson vortices driven by strong dc currents in layered superconductors. Dynamic equations for interlayer phase differences in a stack of coupled superconducting layers were solved to calculate a drag coefficient η(J) of the vortex as a function of the perpendicular dc current density J. It is shown that Cherenkov radiation produced by a moving vortex causes significant radiation drag increasing η(v) at high vortex velocities v and striking instabilities of driven Josephson vortices moving faster than a terminal vc. The steady-state flux flow breaks down at ν > v …