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  • 32.80.Pj  (7)
  • 07.77  (1)
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 44 (1987), S. 105-106 
    ISSN: 1432-0630
    Schlagwort(e): 07.77 ; 29.25
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Low-energy positron emission from tungsten moderators, placed at a electron accelerator beam stop slows down with increasing moderator temperature. Efficient positronium formation is reported on untreated and unoriented metal surfaces at higher target temperatures.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 59 (1994), S. 257-263 
    ISSN: 1432-0649
    Schlagwort(e): 32.80.Pj ; 32.30.Bv
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Ion traps are particular usefully devices for precision spectroscopy on ionic ground states in the microwave domain. Although ultimate precision is achieved only with laser-cooled single ions, in many cases the precision obtained using large uncooled clouds of ions is sufficient for many requirements in atomic physics. The stronger signal in this case makes possible experiments on forbidden transitions or on systems with complex spectra and many substates. Recent examples of laser-microwave double resonance spectra on Pb+ and Eu+ are presented along with attempts to laser-cool a large ion cloud in order to reduce uncertainties from the second-order Doppler effect.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 62 (1996), S. 511-513 
    ISSN: 1432-0649
    Schlagwort(e): 32.80.Pj ; 07.65.Eh ; 07.75.h
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Deviations from the ideal quadrupole potential in a Paul ion trap create nonlinear resonances at certain operating points inside the stability diagram, where in the absence of potential pertubations storing times are very long. In the presence of those pertubations, however, the ions are lost from the trap. Since these resonances are mass dependent and the mass resolution is of the order of 100 it can be used to separate isotopes of a given element by choosing suitable trap operating conditions. Experiments on a natural mixture of Eu+ ions of mass 151 and 153 show that in a simple way, by proper choice of the operating point, the ions can be completely separated and laser-induced optical spectra of a single isotope can be received. This is the first time that mass separation in a Paul trap is performed by nonlinear effects in contrast to the usual way of using the mass dependent boundaries of the stability diagram
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 29 (1994), S. 159-161 
    ISSN: 1434-6079
    Schlagwort(e): 32.70.Fw ; 32.80.Pj
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The lifetimes of both metastable 3D-levels of Ca+ have been measured using the ion storage technique. Operation at UHV-conditions eliminated the earlier reported problems of collisional finestructure mixing between those states [1], which is inherent to measurements at buffergas background. The results of τ(D 3/2)=1113(45) ms and τ(D 5/2)=1054(61) ms improve our earlier result [1] by almost one order of magnitude and are in good agreement with recent theoretical calculations [3, 4, 5].
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 25 (1993), S. 295-298 
    ISSN: 1434-6079
    Schlagwort(e): 32.70.Fw ; 32.80.Pj
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The lifetime of the metastable 3D3/2 and 3D5/2 states of Ca+ ions is determined in a r.f. ion trap by laser excitation of this levels and subsequent time delayed probing of the state population by a second laser. In a buffer gas atmosphere of about 10−5−10−6 mbar of He we observe quenching to the ground state and strong finestructure mixing of the two D-states. This mixing allowes only the determination of the combined lifetime. Our result of τ(3D)=1.24(39) s is in good agreement with theoretical calculations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 24 (1992), S. 339-342 
    ISSN: 1434-6079
    Schlagwort(e): 32.70.Fw ; 32.50.+d ; 32.80.Pj
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A discrepancy exists between theoretical and experimental lifetimes of the metastable 5D 3/2 state in Ba+. In order to redertermine that lifetime, we probe the population of the metastable 5D 3/2 state of a Ba+ ion cloud stored in a Paul ion trap in the presence of He buffer gas as the function of time delay after pulsed laser excitation of this state. The measured decay rates at different buffer gas pressures are extrapolated to zero pressure and we obtain a radiative decay time of 48.0±5.9 s. This is not in agreement with theoretical predictions of about 80 s, but reduces the discrepancy from a previously reportet experimental value of 17.5 s. If the possibility of finestructure mixing to an adjacent 5D 5/2 level by collisions is considered our value represents a lower limit of the radiative lifetime for the 5D 3/2 state.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 28 (1993), S. 87-88 
    ISSN: 1434-6079
    Schlagwort(e): 33.80.Gj ; 32.80.Pj
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract In an ion trap experiment we have determined the vibrational population of the lowest 9 vibrational levels of H 2 + . We used photodissociation of the trapped molecules by 248 nm light from an excimer laser and the dependence of the photodissociation cross section from the vibrational state. Our results are in good agreement to calculations, which are based on the Franck-Condon principle, but include a variation of the internuclear distance in the transition matrix element.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    The European physical journal 25 (1993), S. 103-105 
    ISSN: 1434-6079
    Schlagwort(e): 31.70.Hq ; 32.80.Bx ; 32.80.Pj
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The time constants for population relaxation of optically pumped Pb+ ions in a Paul ion trap have been determined in a He buffer gas atmosphere with additional components of other gases. For the 6P 1/2 ground state of Pb+ and an ion temperatur of 104 K we find cross sections of 0.72(0.33)·10−17 cm2; 0.59(0.38)·10−15 cm2; and 2.56(0.74)·10−14 cm2 for He, N2 and O2, respectively. The error includes an estimated 20% uncertaincy in the pressure calibration of a residual gas analyser.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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