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ABSTRACT: A program for atomic collisions involving highly charged ions is described. The ions are produced as recoils using the pulsed beam of 110 MeV 12C ions from the Stockholm 225 cm cyclotron. With argon as target gas we produce charge states q = 1-10 and with neon q = 1-6. Relative cross sections are given. The recoil ions are used as projectiles in low-energy (keV) collisions with another target. Preliminary cross-sections for Arq+-Ar collisions are presented.
Physica Scripta 02/2007; 1983(T3):163. · 1.20 Impact Factor
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ABSTRACT: 209Po, with one neutron less and two protons more than 208Pb, has been studied in the electron capture decay of 209At. Most of the observed states below 2 MeV excitation can be interpreted as having dominant components corresponding either to one-neutron-hole states or to the coupling of a p1/2 neutron hole to (h9/2)2J ≠ O configurations. Several M1 and E2 transition rates were measured. These, as well as level energies, generally show good agreement with theory. The main part of the 209At electron capture decay proceeds to a 9/2+ level at 2 312 keV, which is interpreted as a core-excited state.
Physica Scripta 02/2007; 4(4-5):137. · 1.20 Impact Factor
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ABSTRACT: The decays of 1.8 h 205Po and 37 min 203Po have been investigated. γ-rays were recorded in singles and coincidence using Ge(Li) detectors. Conversion electrons were studied using a Si(Li) detector as well as a double-focusing magnetic spectrometer. Many transition multipolarities have been determined from internal conversion coefficients. Fairly complete decay schemes are presented for the two nucleides. Also the half-life of a 1/2+ level at 1497 keV in 205Bi was measured to be 7.9±0.7 μsec.
Physica Scripta 01/2007; 5(1-2):41. · 1.20 Impact Factor
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ABSTRACT: The beam-foil method has been used to measure lifetimes for six levels in Si I. The results are compared with emission data and theoretical values. Improved experimental values are also given for a number of previously measured levels in Si II-Si IV.
Physica Scripta 01/2007; 21(6):820. · 1.20 Impact Factor
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ABSTRACT: Absolute cross sections for single and multielectron processes in 1.8q keV collisions, Arq+ + B → Arr+ + Bs+ + (s + r - q)e- have been measured for the targets Ne, Ar and Kr. By means of a coincidence time-of-flight technique, the charge state of the projectile before and after the collision and the charge state of the target ion are determined. The projectile charge ranges from one to nine, while s at most reaches six (Kr), five (Ar) and four (Ne). The experimental technique is discussed and a simple model for absolute cross sections σq,rs is proposed.
Physica Scripta 11/2006; 33(4):310. · 1.20 Impact Factor
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ABSTRACT: Absolute angular differential capture cross sections for Arq+ ions, where q = 6, 7, 8, 9 and 11, colliding with Ar at an energy of 1.8q keV are reported. Absolute total cross sections for q = 12 and 13 are also included. Measuring the final projectile charge, the charge of the target ion and the scattering angle in coincidence, reactions where the target lost up to six electrons were observed. Both absolute and differential cross sections are compared with theoretical predictions based on several extensions of the classical over-barrier model.
Physica Scripta 11/2006; 36(5):756. · 1.20 Impact Factor
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ABSTRACT: Electron capture process, in which the projectile charge (q) is lowered by one unit, have been recorded by means of high-resolution energy-gain spectroscopy for 4q keV Xeq+-Xe (15 ≤ q ≤ 35) collisions. The ratios, R, between the cross sections for the transfer ionisation and single-electron capture were extracted from the measured spectra. The quantity R increases slowly for charges up to q = 25 and decreases rapidly for higher q. Relying on the extended classical over-barrier model we relate R to the branching ratio for autoionisation, F, through R = k F, and estimate the variation in k as a function of q. On the basis of the extended classical over-barrier model we ascribe the decrease in R at high q to an increase in radiative stabilization of double-Rydberg states formed in slow Xeq+-Xe, q > 25, collisions.
Physica Scripta 09/2006; 42(2):150. · 1.20 Impact Factor
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ABSTRACT: Beam-foil quantum-beat techniques have been used to measure the 3D1-3D2 intervals of 1snd (n=3-8) in 4He. I. A two-spectrometer technique was used as to obtain simultaneously a time calibration from the 1s3p(3P1-3P2) fine-structure separation. The following 3D1-3D2 separations (in MHz) were found: 1323.62.3 (n=3), 553.0+or-0.7 (n=4), 284.1+or-0.6 (n=5), 165.3+or-1.0 (n=6), 101.6+or-1.1 (n=7) and 69+or-3 (n=8). These results are compared with previous measurements and theoretical values.
Journal of Physics B Atomic and Molecular Physics 01/2001; 9(12):L345.
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ABSTRACT: The 3P1-3P2 659 MHz quantum beat pattern of the 388.9 nm 2s-3p HeI transition has been measured as a function of carbon foil thickness using both He+ and HeH+ projectiles with the He energies varying from 70 to 260 keV. It is shown that the beat amplitude ratio A(HeH+)/A(He+) is a strong function of the foil thickness. An appreciable destruction of the alignment results for molecular ions impinging on the thinnest foils, corresponding to the smallest distance of the molecular fragments. A qualitative explanation of the result is suggested.
Journal of Physics B Atomic and Molecular Physics 12/1998; 13(6):L205.
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ABSTRACT: Angular differential cross sections for Arq+ ions, where q=8, 9 and 11, colliding with Ar at an energy of 1.8q keV are reported. The final charge state of the projectile together with its scattering angle were measured in coincidence with the charge of the target ion. Processes where the target lost between one and five electrons were observed. The results are compared with two different versions of the classical over-barrier model.
Journal of Physics B Atomic and Molecular Physics 12/1998; 20(5):L165.
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ABSTRACT: Experimental cross sections for single and double ionisation of helium by 0.13-15 MeV AMU-1 ions of charge 1-8 are presented. Where necessary, coincidence techniques were applied to distinguish between pure ionisation and ionisation involving electron capture. For high ion velocities, double ionisation takes place either through a shake-off or through a two-step process. The perturbative shake-off mechanism dominates only for the lowest ion charges and projectile energies above 10 MeV AMU-1. A reliable semi-empirical expression which determines the ratio between the double and single ionisation cross sections over a wide region of ion charge and velocity is given. The difference between double ionisation by equi-velocity electrons and positive ions is discussed. It is concluded that no reliable theoretical description of double ionisation exists for combinations of ion charge and ion velocity which give cross sections close to the maximum values.
Journal of Physics B Atomic and Molecular Physics 12/1998; 17(17):3545.
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ABSTRACT: Using low-energy recoil ions produced by 110 MeV C4+ projectiles the authors have applied time-of-flight techniques to identify simultaneously q, r and s, measuring cross sections for the Arq++Ar to Arr++Ars++(r+s-q)e- reactions at 1.8 q keV. Cases with up to five electrons transferred were observed.
Journal of Physics B Atomic and Molecular Physics 12/1998; 17(24):L877.
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ABSTRACT: For the first time an optical transition between bound states in a negative ion of an atom has been established experimentally. The transition at 3490 AA is observed after beam-foil excitation. By applying an electric field it is shown to belong to the Li- spectrum. According to Bunge (1980) it connects two core-excited quintet states in the negative lithium ion.
Journal of Physics B Atomic and Molecular Physics 12/1998; 13(14):L441.
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ABSTRACT: For xenon ions with charge states up to 31, colliding with a helium gas target, the authors have measured absolute total cross sections for the different possible charge changing processes at low (4q keV) energy. Projectiles and recoil ions were registered in coincidence, allowing the determination of the recoil ion charge state from its time of flight. For reactions where the projectile has picked up one electron, those where the target has lost two electrons ('transfer ionisation') always make up a substantial fraction of the total cross section. For 'true' double electron transfer the cross section is always small ( approximately=10-16 cm2), and does not vary significantly as a function of projectile charge.
Journal of Physics B Atomic Molecular and Optical Physics 12/1998; 21(8):L187. · 1.88 Impact Factor
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ABSTRACT: A beam-foil measurement of the meanlife of the 1s 3p
1
P level in He I has been made and yields the value 1.72250.0046 ns. The measurement was made with standard beam-foil techniques and equipment, but special attention was devoted to minimizing sources of uncertainty. The precision far exceeds that of previous beam-foil meanlife measurements and demonstrates that the beam-foil technique is capable of high precision and is competitive with and more flexible than methods such as resonant laser excitation.
Zeitschrift für Physik A Hadrons and Nuclei 02/1976; 279(1):1-6.
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10/1971;
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C. Sébille-Schück,
M. Finger,
R. Foucher,
J.P. Husson,
J. Jastrzebski,
V. Berg,
S.G. Malmskog, G. Astner,
B.R. Erdal,
P. Patzelt,
P. Siffert
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ABSTRACT: The decay scheme of 2.35 h 187Pt has been investigated using isotopically separated samples produced by the ISOLDE facility at CERN. A total of 20 excited levels in 187Ir have been established. For many of these levels, spin, parity and absolute probabilities of depopulating transitions have been determined. The results indicate that the 187Ir nucleus can be described in terms of a single particle Nilsson model including Coriolis coupling between bands ().
Nuclear Physics A.
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M. Finger,
R. Foucher,
J.P. Husson,
J. Jastrzebski,
A. Johnson, G. Astner,
B.R. Erdal,
A. Kjelberg,
P. Patzelt,
Å. Hoglund,
S.G. Malmskog,
R. Henck
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ABSTRACT: Decay properties of neutron-deficient even-mass Au isotopes obtained from the decay of on-line mass-separated Hg isotopes are presented. New information on energies, spins, parities and transition probabilities concerning low-lying states in even Pt isotopes are given. The experimental data are compared with the available theoretical predictions.
Nuclear Physics A.
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P.G. Hansen,
P. Hornshøj,
H.L. Nielsen,
K. Wilsky,
H. Kugler, G. Astner,
E. Hagebø,
J. Hudis,
A. Kjelberg,
F. Münnich, [......],
J.P. Husson,
J. Jastrzȩbski,
A. Johnson,
J. Alstad,
T. Jahnsen,
A.C. Pappas,
T. Tunaal,
R. Henck,
P. Siffert,
G. Rudstam
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ABSTRACT: Short-lived isotopes of argon, krypton, silver, cadmium, tin, iodine, xenon, platinum, gold, mercury, polonium, radon and francium have been studied by the on-line isotope separator technique. Nuclear decey data are presented.
Physics Letters B.
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ABSTRACT: Absolute cross sections have been measured for a variety of multi-electron processes in low-energy collisions of multiply charged argon recoil ions with neutral argon. The cross sections are compared with theoretical estimates based on an extension of the classical barrier model. Comparison is also made with the statistical theory of Müller et al.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms.
