A. Marelius

The ∥ΔK∥ = 1, E1 transitions in odd-mass isotopes of Tb and Eu

Lifetime measurements have been performed for the 52− [532] intrinsic state in the Tb isotopes with A = 155, 157, 159 and 161. The rates of the ∥ΔK∥ = 1, E1 transitions in these isotopes, as well as in 153Eu and 155Eu, are discussed. With the Nilsson model as a starting point, the effects of pairing correlations and Coriolis coupling are calculated. It is found that these effects are not sufficient to account for the essential features of the experimental results. It is suggested that dipole contributions arising through octupole excitations are of importance.

Lifetimes of excited states in 193Ir

Abstract The lifetimes of four excited states in 193Ir have been measured by a delayed coincidence technique. The results are: 73.0 keV level, T 1 2 = 6.3 ± 0.2 ns ; 138.9 keV, T 1 2 = 74 ± 11 ps ; 180.0 keV, T 1 2 = 78 −28 +21 ps ; 460.5 keV, T 1 2 = 14 ± 9 ps . Furthermore upper limits of the lifetimes of the 557.3 and 559.2 keVlevels have been shown to be 50 ps and 200 ps, respectively. A comparison is made between experimental and theoretical transition probabilities for the transitions de-exciting the 180.0 keV level.

Transition probabilities of excited nuclear states in 125Te

Abstract The lifetimes of eight excited states in 125 Te have been measured by the delayed coincidence technique. A comparison is made between experimental and theoretical M1 and E2 transition probabilities.

Conversion coefficients of transitions in111Cd by a new precision method

An electron-electron coincidence method for precise measurements of internal conversion probabilities is described. By usingK-Auger electrons the atom itself provides a unity standard in the same nuclear decay. The method is applied to the decay of111In in which theK-conversion probability of the 245 keV transition is determined to be 0.0494±0.0011. Relative internal conversion intensities and transition energies are determined using a double focussing spectrometer. These data make it possible to calculate conversion coefficients for all electron shells.

Beam-foil Spectra of Chlorine and Oxygen Ions at Beam Energies of 6-42 MeV

A tandem accelerator has been used for beam-foil excitation of chlorine and oxygen with beam energies from 6 MeV up to 42 MeV. Hydrogen-like transitions in ClVI to ClXIV and OVI to OVIII have been observed in the wavelength region 2 000-5 700 A. The variation in the intensity of the lines with the beam energy has been used to determine the ionization stage of the ions producing the lines.

Decay energy of 139Ce and lifetime of the 166 keV level in 139La

Abstract The K-capture probability of the electron capture decay of 139 Ce was measured by Auger electron-conversion electron coincidence technique to be 0.68±0.02 and the decay energy was calculated to be 85±4 keV. The lifetime of the 166 keV level in 139 La was measured to be 1.48±0.03 ns.

212Pb (ThB) as a Time Calibration Standard for Delayed Coincidence Measurements

Halflives of some excited states in decay products of ThB (212Pb) have been measured by the delayed coincidence technique. For 208Pb the results are: 3 198 keV level 286?26 ps, 3 475 keV level 4?3 ps, 3 961 keV level ? 18 ps. For 212Bi the results are: 238 keV level ? 5 ps, 415 keV level ? 10 ps, 115 keV level (8?4) ps. The use of ThB, 60Co and 198Au as time calibration standards is discussed.

Radiative Electron Capture by Multiply-Ionized Chlorine Atoms

Radiative electron capture by highly ionized chlorine atoms passing through solid targets has been studied. The energy and angular distribution of the radiation has been measured as well as the cross-section of the process and its energy dependence. There is shown to be agreement between experimental data and theoretical values obtained from a modified Bethe-Salpeter model.

A coincidence spectrometer method for measuring the K-capture probability applied to 111In

Abstract A new method for measuring K-capture probabilities is described. The experimental requirements for the method are a coincidence beta spectrometer, a fast coincidence circuit and a time-to-pulse-height converter. The method is applicable with high precision in several nucleides and also in cases where the subsequent de-excitation of the daughter nucleus involves appreciable internal conversion. The method is illustrated by a measurement of the K-capture probability for 111In. The result is 86.7±0.7% K-capture probability in agreement with the theoretical value including the correction for exchange and overlap effects.

Lifetime Measurements for some Δ n = 0 Transitions in Cl XIII-Cl XV

A beam-foil investigation of chlorine at energies up to 48 MeV has been performed in the wavelength region 300-1100 A. Hydrogen-like transitions, as well as Δn = 0 transitions, belonging to Cl XII-Cl XV were observed. Radiative lifetimes and f-values are reported for some important Δn = 0 transitions, 2s 2S1/2-2p 2P3/2 and 2s 2S1/2-2p 2P1/2 in Cl XV, 2s2p 1P1-2p2 1D2 in Cl XIV and 2s2p2 2P3/2-2p3 2D5/2 in Cl XIII.