Bulletin of the American Physical Society
74th Annual Gaseous Electronics Conference
Volume 66, Number 7
Monday–Friday, October 4–8, 2021;
Virtual: GEC Platform
Time Zone: Central Daylight Time, USA
Session PR23: AMP Gateway and Electron Collisions |
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Chair: Robin Cote, University of Massachusetts Boston Room: GEC platform |
Thursday, October 7, 2021 10:15AM - 10:45AM |
PR23.00001: A Science Gateway for Atomic and Molecular Physics: Democratizing Atomic and Molecular Physics Research and Education Invited Speaker: Barry I Schneider The objective of this project is to create a comprehensive cyberinfrastructure (CI) for the atomic and molecular physics (AMP) community, where practitioners can access a synergistic, full-scope platform for computational AMP through the AMP science gateway (AMPGateway). This AMPGateway will initially host nine state-of-the-art AMP software suites. It will be powered by an advanced CI enabling a flexible and easy-to-use platform for the broad AMP community. The gateway-hosted AMP applications are contributed by an internationally recognized group of AMP theorists who have developed best-of-breed approaches for computing atomic/ionic structure, electron collision/photoionization cross sections and control of atomic and molecular systems by laser-atom/molecule interactions. The AMP scientific group is complemented by experts in CI and computational science capable of delivering advanced CI and high-performance computing integration expertise to the broader AMP community, an end-user base of over 3000 in the American Physical Society's Division of Atomic, Molecular, and Optical Physics (DAMOP) alone. The combined efforts of the group will enable a significantly larger fraction of the AMP community to perform AMP science at a level currently only available to a few isolated groups. Without such a coordinated and combined effort, it is unlikely this ambitious project could succeed. The group is dedicated to making the AMPGateway the premier CI for researchers, students, and educators interested in AMP. |
Thursday, October 7, 2021 10:45AM - 11:15AM |
PR23.00002: B-Spline Atomic R-Matrix Calculations on the AMPGateway Invited Speaker: Kathryn R. Hamilton The B-spline R-matrix (BSR) approach [1], developed by the late Oleg Zatsarinny, is an alternative formulation of the well-known R-matrix method developed in Belfast under the leadership of Philip Burke [2]. The program computes transition-matrix elements for electron collisions with many-electron atoms and ions as well as photoionization processes at varying levels of sophistication. From these, cross sections and other observable quantities can be obtained. Atomic structure information can also be generated with BSR through energy levels and oscillator strengths. |
Thursday, October 7, 2021 11:15AM - 11:30AM |
PR23.00003: Benchmark Calculations for Electron Collisions with Ytterbium. Klaus R Bartschat, Kathryn R Hamilton Cross sections for electron collisions with ytterbium are needed to model the enrichment process for the creation of Lu-177, which carries great promise in cancer treatments [1]. While a few experimental data and theoretical predictions are available [2,3], the comprehensive dataset needed for the modeling requires results for a large number of discrete transitions as well as ionization over an extended energy range. We used the Dirac B-Spline R-matrix (DBSR) method [4] to perform such calculations with a variety of states included in the close-coupling expansion. Our 20-state model (DBSR-20) couples the (4f145p66s2)1S0 ground state to all states with dominant configurations 4f145p66s6p and 4f145p65d6s, selected states with 4f145p65d 6p, and the (4f135p65d6s2)1P1 state, which provides an optically allowed 4f –> 5d single-electron excitation pathway from the ground state. We compare the predictions with those from a 59-state (physical states only) approach as well as a DBSR-RMPS model, which accounts for coupling to the ionization continuum through pseudo-states that also provide the ionization cross section. |
Thursday, October 7, 2021 11:30AM - 11:45AM |
PR23.00004: A method to calculate uncertainties on dielectronic recombination rate coefficients Stuart D Loch, Hans Werner van Wyk, Connor P Ballance, Martin O'Mullane, Adam R Foster, Kyle Stewart There is a need for uncertainties on calculated atomic data, for use in spectroscopic diagnostics and plasma modeling codes. The calculation of such uncertainties is a challenging problem, with much recent progress having been made by a number of groups. A general method is presented that can be used to assign uncertainties on atomic collision processes. It uses a Bayesian approach with a Markov Chain Monte-Carlo implementation. The method has been applied to dielectronic recombination, with results being illustrated for a number of iso-electronic sequences, showing good agreement with experimentally measured dielectronic recombination rate coefficients and the expected scaling with electron temperature and ion stage. |
Thursday, October 7, 2021 11:45AM - 12:00PM |
PR23.00005: Electron energy deposition in molecular hydrogen : a monte-carlo simulation using convergent close coupling cross sections. Reese K Horton, Dmitry V Fursa, Liam Scarlett, Igor Bray, Mark C Zammit, Patrick C McNamara, Daniel Cocks A Monte-Carlo simulation of electron energy deposition in molecular hydrogen was conducted with the aim of calculating standard energy deposition parameters. These include the mean energy deposited per ion pair (w) and the mean number of induced dissociations. Molecular convergent close-coupling (MCCC) cross sections were used as input into the simulation. These provide a substantial improvement in accuracy over other commonly used electron-H2 scattering data sets. The calculated high energy value of w was 36.3 eV, yielding excellent agreement with the high energy value of 36.5 ± 0.3 eV recommended by the ICRU. An analysis of the spread in calculated values due to the uncertainty in the input cross sections was also conducted. Qualitative features of the number of induced dissociations observed experimentally were reproduced by the simulation. Specifically, the incident electron energy at which secondary electrons produced via ionisation begin to induce more dissociations than the primary electron was identified. Finally, a comparison of the results with those of a previous simulation highlights the effect of accurate collision data on the results of such simulations. |
Thursday, October 7, 2021 12:00PM - 12:15PM |
PR23.00006: Absolute O atom density measurements by actinometry: comparison to cavity ring-down spectroscopy Edmond Baratte, Andrey Volynets, Dmitry Lopaev, Cherif Si Moussi, Jean-Paul Booth, Olivier Guaitella Optical emission actinometry is widely used to determine the densities of reactive gas-phase atomic species like oxygen atoms, since it is a simple, non-intrusive technique requiring little equipment. The accuracy of absolute measurements however depends on the excitation cross-sections of both the studied species and the actinometer gas, which are typically poorly characterised. |
Thursday, October 7, 2021 12:15PM - 12:30PM |
PR23.00007: Electron and photon impact ionization of molecules using a complex Gaussian representation of continuum states Abdallah Ammar, Arnaud Leclerc, Lorenzo Ugo Ancarani This theoretical work deals with ionization of small molecules by photon or electron impact. The focus is on the description of the electron ejected into the continuum. |
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