The 2p-3d Electron Transition Multiplet of Ar +13 : A Stellar Density Diagnostic Laura Heeter Kristina Naranjo-Rivera

Introduction Applications Density and temperature diagnostic for astrophysics -Stellar corona, solar flairs -Naturally occurring thermal plasma -Chandra Observatory x-ray data

L-shell spectral peaks Simple Structure Density sensitivity (Å)

Lepson et al. Survey 2p-3d Ar +13 Spectral Peaks

Trabert et al. Study 3d 1 5/2 3d 1 3/2 2p 2 3/ 2 Metastable State 2p 1 3/2 Ground State 2p 1 1/2 Forbidden Transition Metastable level- 9.7 ms atomic lifetime

Theory 3d 1 5/2 3d 1 3/2 2p 2 3/ 2 Metastable State 2p 1 3/2 Ground State 2p 1 1/2 Forbidden Transition Wavelength (Å) Dr. Ming Feng-Gu –Peak intensities will invert with increased beam current density –Increased excitation to metastable state 2p 1 3/2

Hypothesis Sensitivity to beam current density Increased electron excitation to metastable level

Objective Stellar Object EBIT Ar +13 Emission Spectra Density? DensityAr +13 Emission Spectra Electon Beam Ion Trap

EBIT Liquid Helium Reservoir Liquid Nitrogen Reservoir Trapping Region Collector Electron Gun Superconducting Helmholtz Magnet

Methods Prepare EBIT Excite Ar to Ar +13 Determine Constant Beam Energy Collect & Analyze Spectral Images Calculate Intensity Ratios Compare Experimental and Theoretical Data

Results Inverse relationship: beam current and intensity ratio

Results vs. Theory Wavelength (Å)

Comparison to Theoretical Models Density (cm –3 ) Ar +13 experimental data Monoenergetic beam Maxwellian plasma model

Discussion Increased population of metastable state occurred as beam current density increased Accuracy promises Ar +13 as a useful density diagnostic

Further Studies Broader density range Use other more abundant elements –Mg, Fe, Ni, and more –Currently Fe +21 is being tested

Acknowledgements The EBIT Team –Dr. Peter Beiersdorfer –Edward Magee –Dr. Hui Chen –Dr. Elmar Träbert –Ming Feng-Gu Ms. Fruen and the Research Class

The 2p-3d Electron Transition Multiplet of Ar +13 : A Stellar Density Diagnostic Laura Heeter Kristina Naranjo-Rivera

Elaboration of Methods: Analyze Ar +13 Spectra Igor Pro N +5 calibration Sum like data

Calculate Intensity Ratios R = (I (3d5/2→2p3/2) + I (3d3/2→2p3/2) ) / I (3d3/2→2p1/2)