Richard Marrus

Atomic Physics 5

Reviews of the current state of research in atomic physics are presented. Experimental work on such topics as search for parity violation, spectroscopy and collision processes of fast, highly-stripped heavy ions, exotic atoms, high Rydberg states, laser spectroscopy, photoelectron spectroscopy, and others is described. Twenty-seven papers were prepared for the data base. (GHT)

ATOMIC BEAM STUDIES OF SOME RADIOACTIVE ISOTOPES OF REFRACTORY GROUP ELEMENTS

Abstract The spins of several neutron-produced isotopes in the refractory region have been measured by the atomic-beam method. They are found to be Ta 183 (I = 7 2 ) ; W 185 (I = 3 2 ) ; W 187 (I = 3 2 ) ; Re186 (I = 1); Re188 (I = 1); Ir192 (I = 4); and Ir194 (I = 1). With the exception of Ir192, these values are consistent with plausible state assignments based on the Nilsson model and with the coupling rules for odd nuclei of Gallagher and Moszkowski. A new method is described for the production of atomic beams of materials having high melting points and low vapour pressures.

Doppler-tuned beam-foil X-ray spectrometer

Abstract A new type of X-ray spectrometer for use with fast foil-excited beams has been devised and tested. The spectrometer operates by matching the Doppler-shifted emission from the beam with a known absorption feature (such as a K-edge) in a thin filter between the source and the detector. Tuning is accomplished by varying the angle between the detector and the beam. Knowledge of the angle, beam velocity and the filter absorption profile is sufficient to determine the emission spectrum of the beam source. Resolving powers of 10 3 to 10 5 are expected. A prototype device has been constructed and tested at the Berkeley HILAC. In initial experiments, the energy of the 2 1 P 1 −1 1 S 0 transition of heliumlike argon (Ar XVI) was measured by bringing the emission from the 412 MeV Ar beam into coincidence with the L III absorption edge of Ag near 3.36 keV. The principle of this spectrometer can be extended to other spectral ranges, and it should be useful for both survey and high-precision measurements

Nuclear spins of neodymium-147 and promethium-147

Abstract The nuclear spins of 11 d Nd147 and 2.6 y Pm147 have been measured to be I = 5 2 and I = 7 2 respectively by the atomic beam magnetic resonance method. The result for Nd147 confirms an earlier measurement made by paramagnetic resonance. The result for Pm147 is surprising in view of the fact that no beta transition has been observed between the ground states of these two isotopes.

Forbidden decay modes of one- and two-electron ions

Abstract There are four forbidden decay modes that are obserbable in one- and two-electron atoms. In one electron atoms, 2 2 S 1 2 level decays to the ground state primarily by a two-photon process. This is also true of the 2 1 S 0 state of two-electron atoms. Moreover, the M1 decay of 2 3 S 1 and the M2 decay of 2 3 P 2 are also observable processes in two-electron atoms. The properties of these decays and an experiment to detect them and measure their lifetimes will be described.

Hyperfine structure and nuclear moments of protactinium-233

Abstract By means of the atomic-beam magnetic resonance method using radioactive detection, the hyperfine structure of 91Pa233 ( T 1 2 = 27.4 days ) has been investigated. Three low-lying states are found to be present in the beam, characterized by electronic angular momenta J = 11 2 , 9 2 and 7 2 and g values gj = −0.8141(4), −0.8062(15) and −0.7923(15) respectively. From these results it is inferred that the ground-state configuration of protactinium is almost certainly (5f)2(6d)1(7s)2. The nuclear spin is measured and found to be I = 3 2 and the magnetic dipole and electric quadrupole hyperfine structure coupling constants are measured to be A = ±595(30) MHz and B = ∓2400(300)MHz respectively. From a direct measurement, the nuclear moment is found to be μI = +3.4(0.8) n.m. From the hyperfine-structure constants and detailed calculations involving the electronic wave functions, the quadrupole moment is inferred to be Q = −3.0 barns.

Observation of the magnetic-dipole decay of the 23S1 state of helium-like Si XIII, S XV, and Ar XVII

Abstract The observation in a laboratory experiment of the magnetic-dipole decay 2 3 S 1 -1 1 S 0 in the helium-like atoms Si XIII, S XV, and Ar XVII is reported.

Experimental and theoretical study of QED corrections in the ground state of heliumlike iron

The energy of the Lyβ and Lyγ lines of heliumlike iron has been measured with a precision of 25 ppm. The study of these transitions involving levels of high principal quantum number (n=3 andn=4) provides us with informations on the ground state 11S0 of the ion. The experimental values are compared to MCDF calculations including QED two-body corrections.

Atomic beam study of the rubidium 85, 87 relative isotope shift

Abstract The 85, 87Rb relative isotope shift has been investigated by an atomic beam technique and found to be 0.35 ± 0.05 m-1. The 87 Rb 5 2 P 1 2 hyperfine structure has also been determined and agrees with previous measurements.