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Calorimetric low-temperature detectors for low-energy (E#<=#1 MeV/amu) heavy ions and their first application in the accelerator mass spectroscopy for trace analysis of "2"3"6U / Kalorimetrische Tieftemperaturdetektoren fuer niederenergetische (E#<=#1 MeV/amu) Schwerionen und ihr erster Einsatz in der Beschleuniger-Massenspektrometrie zur Spurenanalyse von "2"3"6U

  • Kraft-Bermuth, S.
  • univ., 18 mainz
Publication Date
Jan 01, 2004
OpenGrey Repository


In the thesis presented here, calorimetric low temperature detectors were for the first time applied in accelerator mass spectrometry (AMS) to determine the isotope ratio of "2"3"6U to "2"3"8U in several samples of natural uranium. The detectors consist of a superconducting aluminium film deposited onto a sapphire absorber which is used as thermistor. An energetic heavy ion deposits its kinetic energy as heat in the absorber. The temperature rise is detected by the resistance change of the superconductor. The AMS experiments were performed at the tandem accelerator VERA of the ''Institut fuer Isotopenforschung und Kernphysik'' of the University of Vienna. In an energy range of 10-60 MeV, a relative energy resolution of #DELTA#E/E=7.10"-"3 could be achieved, one order of magnitude better than with conventional ionization detectors. Improving thermal and electronic noise yielded in a second experiment for uranium ions with E=17 MeV a relative energy resolution of #DELTA#E/E=4.6.10"-"3. The energy response of the detectors was linear over the whole energy range and independent of the ion mass. Down to a level of 0.1%, no pulse height defect was observed. With the energy resolution obtained it is possible to determine the isotope ratio of "2"3"6U/"2"3"8U for several samples of natural uranium. With the resolution achieved it is possible furthermore to apply the detectors in several test experiments for direct mass identification of heavy ions using a combined energy/time of flight measurement. In these first tests, a mass resolution of #DELTA#M/M=(8.5-11.0).10"-"3 was achieved. In a first test to apply the detectors for detection of so called ''super heavy elements (Z>=112)'', the large dynamic range allowed to identify the reaction products and their alpha decays simultaneously and time dependent. (orig.) / SIGLE / Available from: <a href= target=NewWindow></a> / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische Informationsbibliothek / DE / Germany

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