Theoretical calculation of transition probabilities and lifetimes of levels of the 4d 95p configuration of CdIII

The configuration superposition method realized in the basis of Hartree-Fock functions and transformed radial orbitals with variable parameters is applied to ab initio calculation of electronic transition probabilities from levels of the 4d ⁹5p configuration of the CdIII ion. Relativistic corrections in the energy spectra are calculated within the framework of the Hartree-Fock-Pauli approximation, i.e., in the second order in the fine structure constant. The inclusion of correlation and relativistic corrections makes it possible to achieve a good coincidence of the values of electric dipole transition probabilities calculated with the use of two forms of the operator—the form of length and the form of velocity—for both strong and weak transitions. Using the transition probabilities obtained, radiative lifetimes of levels of the configuration indicated are determined. They are in a good agreement with the currently available experimental data.     

Level structure of the 89-neutron nucleus 153Gd: (I). Levels and gamma-transitions in 153Gd excited in the decay of 153Tb

Investigations of the properties of ¹⁵³Gd excited states populated in ¹⁵³Tb decay were continued. The following measurements were performed: coincidence spectra e^?γ with L41, K93 + L52, K110, K129 + L87 + L88 and K195 + L152 keV conversion electron lines, angular correlations of high energy γ-cascades going through the 109.7 keV level, delayed e^?γ and e^?e^? coincidence spectra to determine the half-lives of 41.5, 93.3, 109.7, 129.1,183.5, 212.0 and 216.1 keV states, R(135°, ± B) parameters of IPAC for the 102–110 and 83–129 keV cascades using ¹⁵³Tb sources implanted into Fe foil.A decay scheme of ¹⁵³Tb containing 50 excited levels is proposed. Their spins, parities, $\text{log}\text{?t}$ and, for low-lying levels, also the mean half-lives have been determined. An estimation of the g-factors of the 109.7 and 129.1 keV levels has been given. On the basis of half-lives of investigated states absolute values of reduced γ-transition probabilities for these states have been calculated. The structure of the ground state of ¹⁵³Gd is discussed.     

Measurements of the probability for 1 sσ excitation in very heavy ion-atom-collisions and determination of the binding energy of the 1 σ molecular orbital

Using particle x-ray coincidence techniques, the probability to produceK-shell vacancies in 4.7 MeV/u Pb+Z₂ (42≦Z ₂≦92) collisions for impact parametersb<100 fm was measured. For these impact parameters, the 1sσ excitation probability is greater than 1 σ 10^?2 and the 2p _1/2 σ excitation probability is greater than 1 σ 10^?1. Binding energies of the 1sσ state derived from the measured probabilities agree well with theoretical calculations.     

Calculation of the yield of Xe<Superscript><Emphasis Type="Italic">i</Emphasis>+</Superscript> photoions upon the decay of <Emphasis Type="Italic">M</Emphasis><Subscript>45</Subscript> vacancies through intermediate states in coincidence with energy-selected Auger electrons

A theoretical model is proposed for calculating the yield of photoions detected in coincidence with energy-selected Auger electrons. This model provides a correct explanation for experimental data on the yield of photoions upon ionization of the M₄₅ shell of xenon atoms. In the framework of the proposed model, the intermediate-coupling approximation is used to calculate both the structure of the terms of the N^?2 two-hole states generated through the M₄₅NN Auger decays and the probabilities of branching due to decays of these states into three-hole states upon the Auger, Coster—Kronig, and super-Coster—Kronig transitions. The probabilities of branching for subsequent branches of the cascade decay are calculated in the configuration-average approximation. The results of these calculations are in good agreement with the experimental data.     

The decay of 235U

Twenty-eight γ-rays, ten of which are reported for the first time, have been observed in the decay of ²³⁵U, and all have been placed in a revised level scheme for ²³¹Th. Three new levels at 390.27, 317.42 and 240.82 keV respectively have been proposed and the data are in accord with he results of coincidence studies. Reduced transition probabilities of inter-band γ-ray transitions are calculated from the data and compared with theory and an estimate of the intrinsic quadrupole moment, Q_O has been computed.     

The contribution ofK-electron capture for the production of highly charged Ne recoil ions by 156 MeV bromine impact

The recoil ion production cross sections in 2MeV/amu Br ⁿ⁺+Ne⁰→Br ^n′++Ne ^q+ were measured using a projectile ion — recoil ion coincidence technique where the final charge states of both collisions partners were detected simultaneously. Multiple ionization was found to be the dominant process for the production of low charge state recoil ions whereas the production of highly charged recoil ions is accompanied by electron capture from the Nek-shell. The derived ratio of single to double Ne-k electron capture probabilities indicates deviations from a binomial statistics distribution.     

Untersuchung der Anregungen von186Re nach der (n, γ)-Reaktion

Prompt and delayedγ-γ-coincidences were measured after slow neutron capture in¹⁸⁵Re by use of Ge(Li)-detectors. New isomers were found at 99.4 keV (T_1/2=27±7ns) and at ≈330keV (T_1/2=17.4±0.7 ns). The evaluation of coincidence data established 10 rotational bands with band heads below 700 keV. The level scheme is discussed in detail: Nilsson assignments are proposed for the band configurations, and calculations of Coriolis mixing andγ-transition probabilities are presented which reproduce the experimental level energies and transition intensities very satisfactorily.     

X-ray study of the deep inelastic reactions 1,160-MeV136Xe+Pb and136Xe+232Th

The spectra ofK x-rays emitted by the target-like reaction products in the deep inelastic collisions 1,160-MeV¹³⁶Xe+Pb and¹³⁶Xe+²³²Th were investigated. Target-like x-ray emission probabilities per projectile-like and per target-like product were determined and compared with theoretical predictions of atomic vacancy production in the higher-Z particle (1s }-vacancy production). It is shown that a large fraction of the x-rays is produced by internal conversion ofγ-rays in the higher-Z reaction product. Measurement of target-like x-rays in coincidence with projectile-like and with target-like reaction products allowed the determination of the average survival probability against fission and of theZ-distribution of the highly excited target-like nuclei as a function of theQ value (total kinetic energy loss). The observed average survival probabilities agree qualitatively with theoretical predictions of Wilcke et al. Nuclearreaction-time effects on the 1s σ-vacancy production in these collisions could not be demonstrated with any certainty.     

Small impact parameterK-shell ionisation probabilities and δ-electron spectra

K-shell ionisation probabilities and correspondingδ-electron spectra have been determined for 15 MeV protons and 50 MeV alpha particles on²⁰⁸Pb by measuring the energy spectrum of the scattered projectiles in coincidence with characteristic KX-rays, using a high resolution magnetic spectrograph. The results are in good agreement with SCA calculations.     

Alpha decay of 210At to levels in 206Bi

The α-decay of ²¹⁰At has been investigated with α-γ coincidence techniques. Spins of ²⁰⁶Bi levels below 500 keV have been deduced from recent electron-capture studies of ²⁰⁶Po, reaction studies of ²⁰⁶Bi and present results. Calculations of the α-decay rates and electromagnetic transition probabilities using wave functions in a. truncated configuration space are compared with the experimental results.     

Studies on the low-lying levels in192Pt and192Os populated in192Ir decay

Low-lying levels in¹⁹²Os and¹⁹²Pt are reinvestigated through¹⁹²Ir (73.831d) decay with improved system performance and counting statistics. Experiments show that gamma rays reported in literature with energies 1413, 1237, 1147, 911, 773, 629, 362 and 325 keV are not from the decay of¹⁹²Ir and gamma rays reported with energies 1200, 1056, 920, 904, 784 and 624 keV are resulted from sum-up or pile-up effects of low energy intensive gamma rays. New gamma-gamma coincidence relations are obtained with 105 cm³–110 cm³ germanium detector system. A level at 1384 keV is established in the decay scheme and four newly proposed levels at 1118.31 keV in¹⁹²Os and 1146.95, 1237.35 and 1413.76 keV in¹⁹²Pt are excluded from the decay scheme. Predictions of Interacting Boson Model on level energies andE2 absolute reduced transition probabilities are compared with experimental results.     

Some lifetimes and transition probabilities in Cu(I)

Radiative lifetimes of 7 levels in the Cu(I) 3d⁹ 4s4p configuration have been measured using a delayed coincidence technique; copper vapor was excited in an argon buffer gas and cross sections for collisional destruction of copper levels by argon were also obtained. Transition probabilities of the lines originating from these levels have been determined using the measured lifetimes and branching ratios.     

Levels in104Ru populated by the β−-decay of104Tc

Theβ ^? — andγ-activities of 18.4 min¹⁰⁴Tc have been studied with singles and coincidence measurements. Sources were prepared by chemical separation of technetium from the fission products of thermal-neutron-induced fission of²³⁵U. A revised level scheme of¹⁰⁴Ru up to an excitation energy of 4.26 MeV is proposed. Fromβ-γ coincidence measurements, aQ _β-value of 5.62±0.07 MeV has been obtained.     

Doppler-shift attenuation measurements on Mg by (α, α') and (p,p') reactions

The (α, α') and (p, p') reactions have been used to populate states in ²⁴Mg in order to measure lifetimes of ten states by the Doppler-shift attenuation method. The shifted γ-rays were observed by a planar 5.6 cm³ Ge(Li) detector at 90° to the beam at the target in coincidence with the scattered particles observed in either of two particle detectors located symmetrically with respect to the beam. A computer coupled dual two-parameter arrangement permitted concurrent measurements for all states appreciably populated. The present measured transition probabilities are compared with predictions from a truncated j-j coupling shell-model calculation.     

Spectral shape of the (7/2−→5/2+)-transition in the β-decay of139Ba

The energy spectrum of theβ-decay leading from the ground state of¹³⁹Ba to the first excited state of¹³⁹La has been measured in coincidence with the 166keV-γ-transition. For the measurement a well tested 4π-β-γ-coincidence spectrometer has been used. Because of its highβ- andγ-efficiency the instrument is especially suitable for selecting the spectrum of a weak and short livingβ-component. The measured spectrum has been corrected for distortions due to bremsstrahlung escaping from the Si(Li)-detectors. The shape factor has been determined and compared with former measurements. The significance of matrix elements extracted from the spectral shape is discussed.     

Isomeric transitions in203Bi and205Bi

High spin states in^{203, 205}Bi, populated in the^{203, 205}Tl (α,4n) reactions, have been studied using gamma-ray and conversion-electron spectroscopy. Several previously unobserved isomeric transitions were identified by electron-electron coincidence measurements in both isotopes and in²⁰⁵Bi a new isomer was found. The observed states can be explained as arising from couplings of the oddh _9/2 proton to neutron states in the neighbouring Pb cores. Reduced transition probabilities are derived and discussed.     

124Ba Decay to the 55 124 Cs69 low-spin levels

The decay of¹²⁴Ba to the levels of odd-odd¹²⁴Cs has been studied with on-line mass-separated sources delivered at the Isocele facility. The energy level scheme has been established fromγ-ray singles,γ?γ?t coincidence ande?γ?t coincidence spectra. Spin and parity of several low-lying levels have been assigned on the basis of internal conversion coefficient measurements andβ-branchings. A completely new level pattern including approximately 50 levels and 180γ-rays is proposed for¹²⁴Cs. Several features of this level scheme are discussed and compared to those of neighbouring isotopes.     

Measurement of the mean lifetimes of low spin states in the superdeformed band in133Nd

The mean lifetimes of the lower spin states of the superdeformed band in¹³³Nd have been measured with the coincidence recoil distance method. The reaction used to populate the band was¹⁰⁵Pd (³²S, 2p2n)¹³³Nd at a beam energy of 152 MeV, and the gamma-rays were detected with the POLYTESSA array. The differential decay curve method was used to analyse the data and transition quadrupole moments,Q ₀, were extracted from the measured lifetimes. The results obtained from the three lowest transitions in the superdeformed band are:Q ₀=6.3±0.9 eb (21+/2→17+/2),Q ₀=6.7±1.1 eb (25+/2→21+/2) andQ ₀>5.0 eb (29+/2→25+/2). These results are consistent with previous results for the high spin members of the band, and are compared to theoretical calculations of total routhian surfaces. The calculation of reduced transition probabilities for the transitions that feed out of the band, allows the effect of hindrance due to K-forbiddenness to be investigated.     

The impact parameter dependence of the K MO X-ray emission in208Pb +208Pb collisions

The emission probabilities for quasimolecular K-x-radiation (K-MOR) have been measured in²⁰⁸Pb +²⁰⁸Pb collisions at 4.3 MeV/u and 4.8 MeV/u as a function of the scattering angle using the particle-photon-coincidence technique. The probabilities exhibit a superposition of two exponential slopes with different fall-off constants. We identify the sharp fall off at very small impact parameters (<60 fm) with the K-MOR contribution from the decay of 1sσ-vacancies. The flatter slope for impact parameters larger than 60 fm is attributed to the radiative decay of holes in 2p _1/2 σ molecular states. In this way, experimental “1sσ-MOR-emission probabilities” could be extracted and compared with theory. For 4.3 MeV/u the1sσ- and 2p _1/2 σ-excitation probabilities could also be determined and have been compared to coupled-channel calculations and to a scaling law for 1sσ excitation.