K.W. Kukla

Measurement of the 6p2P3/2 state lifetime in atomic cesium.

We present a precision experimental test of atomic many-body theory that is currently applied to the interpretation of recent parity-nonconservation experiments in atomic cesium. We report the first measurement of the {sup 133}Cs 6{ital p} {sup 2}{ital P}{sub 3/2} state lifetime using resonant diode-laser excitation of a fast atomic beam. The lifetime result of 30.55{plus minus}0.27 ns determines the absorption oscillator strength for the 6{ital s} {sup 2}{ital S}{sub 1/2}--6{ital p} {sup 2}{ital P}{sub 3/2} transition in cesium to be 0.7133{plus minus}0.0064, and establishes the accuracy of recent relativistic many-body calculations of the dipole transition matrix element to 0.5%.

Precision lifetime measurements using laser excitation of a fast atomic beam

Abstract We employ resonant laser excitation of a fast atomic beam to measure excited state lifetimes by observing the decay-in-flight of the emitted fluorescence. Our program includes lifetime measurements of the low lying p states in alkali and alkali-like systems. This work was initiated by the motivation to test the atomic many-body-perturbation theory that is necessary for interpretation of parity nonconservation experiments in cesium. We report new measurements of the 6p 2 P 1 2 and 6p 2 P 3 2 state lifetimes in the 133Cs atom to be 34.934 ± 0.094 ns and 30.499 ± 0.070 ns respectively. With minor changes to the apparatus, we have extended our measurement capabilities to include the 2p 2 P 1 2 , 3 2 states of lithium. We present comparisons between measurements and relativistic calculations of atomic transition matrix elements.

Rydberg transitions in Be‐like Si XI

Measurements of Δn=1 Rydberg transition wavelengths for Be‐like Si XI are presented for 1s22s9l’←1s22s10l and 1s22s8l’←1s22s9l. The large polarizability of the open core 1s22s and configuration interaction with nearby 1s22pnl states yield observable 1‐structure that is compared with the polarization model, Multi Configurational Dirac‐Fock (MCDF) and Many Body Perturbation Theory (MBPT) calculations. We discussed the high‐1 structure of the n=9–10 transition previously in relation to plasma observations. The first application of MBPT calculations to Be‐like Rydberg states was reported with our measurement of the 7I–8K transition in S XIII.

Fine structure energies for the 1s2s 3S-1s2p 3P transition in helium-like ions

We have measured the 1s2s 3S1-1s2p 3P0 and 1s2s 3S1-1s2p 3P2 fine structure transition wavelengths in the helium-like Ar16+ ion, using the beam-foil spectroscopy technique with position-sensitive photon detection. The wavelength results have precisions of < 30 ppm and are sensitive to the total QED corrections to < 0.5%. The measurements confirm the significance of (Zα)4-dependent relativistic corrections to the n = 2 state fine structures suggested by recent calculations. The small remaining discrepancies between these measurements and the accurate theoretical values suggest that the magnitude of uncalculated higher order QED terms is about 0.15(Zα)4 a.u. The status of our experimental search for the 3S13P0 transition in Ni26+ is discussed.

Measurement of the 6 p sup 2 P sub 3/2 state lifetime in atomic cesium

We present a precision experimental test of atomic many-body theory that is currently applied to the interpretation of recent parity-nonconservation experiments in atomic cesium. We report the first measurement of the {sup 133}Cs 6{ital p} {sup 2}{ital P}{sub 3/2} state lifetime using resonant diode-laser excitation of a fast atomic beam. The lifetime result of 30.55{plus minus}0.27 ns determines the absorption oscillator strength for the 6{ital s} {sup 2}{ital S}{sub 1/2}--6{ital p} {sup 2}{ital P}{sub 3/2} transition in cesium to be 0.7133{plus minus}0.0064, and establishes the accuracy of recent relativistic many-body calculations of the dipole transition matrix element to 0.5%.

Measurement of the 6p2P3/2state lifetime in atomic cesium

We present a precision experimental test of atomic many-body theory that is currently applied to the interpretation of recent parity-nonconservation experiments in atomic cesium. We report the first measurement of the {sup 133}Cs 6{ital p} {sup 2}{ital P}{sub 3/2} state lifetime using resonant diode-laser excitation of a fast atomic beam. The lifetime result of 30.55{plus minus}0.27 ns determines the absorption oscillator strength for the 6{ital s} {sup 2}{ital S}{sub 1/2}--6{ital p} {sup 2}{ital P}{sub 3/2} transition in cesium to be 0.7133{plus minus}0.0064, and establishes the accuracy of recent relativistic many-body calculations of the dipole transition matrix element to 0.5%.

Spectroscopy of highly‐ionized atoms using position‐sensitive detection

We report new results of atomic structure and atomic lifetime measurements in highly‐ionized few electron atoms obtained using position‐sensitive detection of extreme ultraviolet emission from excited fast ions. Data is presented from experiments run at the Notre Dame Tandem Accelerator and at the Argonne ATLAS facility using beam‐foil spectroscopy with a photon‐counting position‐sensitive imaging detector. The results include excited state lifetimes in Si XI and Si XII involving both resonance transitions and Rydberg transitions, spectra of high‐ionized He‐like, Li‐like, and Be‐like nickel including comparisons of electron capture and excitation processes for charge selected beams and spectra and lifetimes in highly‐charged bromine ions for both allowed and forbidden transitions.