R. J. Powers

2s Atomic level in muonic 208Pb

Abstract We report the measurement of the energies and the relative intensities of various muonic atomic transitions above 500 keV in 208 Pb including transitions to and from the 2s level. Besides the usual E1 transitions we have observed 3d → 1s and 4d → 2p E2 transitions. Interpretation of these data in terms of various charge distributions is made. Appreciably better fits are obtained by assuming the presence of nuclear polarization and allowing the nuclear polarization parameters ΔE (1 s ) and ΔE (2 s ) of the 1s and 2s levels to vary. Least-squares fits indicate values of ΔE (1 s ) = −8.9±2.7 keV and ΔE (2 s ) = −0.6±0.7 keV. Comparisons with electron scattering results are made.

Measurement of kaonic X-rays from Al, Si, Ni and Cu

Abstract We have identified X-rays associated with stopped negative kaons in Al, Si, Ni and Cu. We report relative intensities, strong interaction energy shifts and strong interaction line broadenings. The measurements are found to be in good agreement with those predicted on the basis of a simple phenomenological potential except for the Ni (5 → 4) transition width.

Neutron Emission Following Muon Capture inCe142,Ce140,Ba138, andSn120

Branching ratios to excited nuclear states formed after muon capture have been measured with Ge(Li) detectors. The delayed gamma rays were observed in studies of muonic Ce-142, Ce-140, Ba-138, and Sn-120, using separated isotopes. The resulting isotopes formed indicate at least a 60% probability of neutron emission upon muon capture, with the most likely product resulting from single-neutron emission. No evidence for delayed proton emission with a probability higher than 2% was found. Using our more precise energies for the observed nuclear transitions, we present revised energy levels schemes for La-141, La-139, Cs-137, and In-119.

The 2s atomic level in muonic 140Ce

Abstract We have observed the 2s → 2p and the 3p → 2s muonic X-ray doublets in 140Ce. Assuming a two-parameter Fermi distribution we find our data are best fit by allowing a 5.4 ± 0.7 keV shift downward in the 1s 1 2 level in reasonably good agreement with the theoretical calculations for nuclear polarization. The sensitivity of our results to a three-parameter Fermi distribution is explored.