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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2485-2487 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Accelerator mass spectrometry (AMS) requires ion sources delivering intense negative ion beams of high stability. In addition, a multitarget system and a vacuum lock for sample loading are essential for efficient operation. We present a new design of a cesium (Cs) negative ion sputter source with the following features: the vacuum chamber of the ion source and the target cassette are at ground potential. Batches of targets can be loaded and unloaded without interrupting the operation of the source. All control systems for sample loading and automatic changing are also at ground potential. This ion source concept has already been successfully applied to AMS at our laboratory. The new design incorporates a spherical Cs surface ionizer to increase the negative ion currents. Difficulties in realizing this concept are the high electric fields inside the vacuum chamber in an environment with high Cs vapor pressure. Also critical are the proper and reliable operation of all mechanical components under these conditions and the large temperature gradients.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    facet.materialart.
    Unbekannt
    North-Holland
    In:  Nuclear Instruments & Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 29 . pp. 326-331.
    Publikationsdatum: 2017-02-13
    Beschreibung: 10Be and 230Th profiles were measured at Site 580 at a depth of 20 m (230Th and 10Be) and 80 m (10Be), corresponding to 360 ka and 1.5 Ma, respectively, with a resolution of approx. 5000 a. The radiometric sediment accumulation rates of 6.2 cmka ( ± 25%) agree well with the average for the last 730 ka (via paleomagnetic stratigraphy). Age corrected concentrations of 10Be range from 2 to 7 × 109atomsg (average 3.5 ± 1). The variations of the 10Be concentrations can be explained by changes in the sediment supply during different climatic conditions. The maxima and the minima of 10Be follow the fluctuations of excess 230Th in the core section during the last 360 ka. Fluxes of both 10Be and 230Th exceed production and vary remarkably throughout time suggesting enhanced scavenging by bioproductivity. At the Brunhess-Matuyama boundary we observe a maximum of 10Be (6.0 ± 0.3.109atomsg, corresponding to 2.5 σ deviation from the average value). However, the observed large fluctuations of Be-10 throughout the core profile make it difficult to interprete this particular maximum.
    Materialart: Article , PeerReviewed
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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