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  • 2000-2004  (63)
  • 1970-1974  (40)
  • 1940-1944  (2)
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 836-838 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: For the International Fusion Materials Irradiation Facility (IFMIF) scenario, a 140 mA deuterium beam in continuous wave (cw) mode with an atomic yield of above 85% is required. The normalized root-mean-square emittance should be less than 0.2 π mm mrad at the entrance of a RFQ. As part of a conceptual design for IFMIF, a new ion source has been developed and is tested at the Institut für Angewandte Physik in Frankfurt. The ion source is of the volume type with a tungsten cathode driving the discharge. Both cw and pulsed mode are possible and were studied. First experiments were carried out with deuterium. 80 mA deuterons with a D+ fraction of above 90% were extracted [A. Maser et al., Rev. Sci. Instrum. 67, 1054 (1996)]. In order to avoid neutron generation by the d–d reaction, hydrogen was used instead of deuterium later on. As far as the ion source and plasma production processes are concerned, the use of hydrogen instead of deuterium is equivalent because of their similar atomic shells. Recently, a 200 mA proton beam at 55 kV was extracted in cw mode (according to Child–Langmuir, 200 mA H+ corresponds to 140 mA D+) with a H+ fraction of 93%. This article will give a detailed description of the ion source and the essential experimental results. Especially, the influence of important physical parameters (such as discharge current and strength of the filter field) on the H+ fraction was studied. By using different kinds of auxiliary gases, the influence on the H+ fraction and the noise level were investigated, too. © 2000 American Institute of Physics.
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 73 (2002), S. 1027-1029 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: For the International Fusion Materials Irradiation Facility project (IFMIF) the Institut für Angewandte Physik at the University of Frankfurt is concerned with developing a high current proton/deuteron ion source. The 1999 "Frankfurt 200 mA Proton Source" is a volume type belonging to the high-efficient ion-sources family. This type of ion source has proven its capability to produce high-current ion beams of a single mass-to-charge ratio at very low-beam emittances. The arc discharge ion source delivers a 200 mA full beam (93% protons) at 55 keV with very high-beam intensities (outlet aperture 8 mm diam). Thus, the beam requirements for the IFMIF project are fulfilled. After having done the basic plasma investigation with a 127° cylinder spectrometer, the quality of the ion beam was a point of interest. Therefore, the beam emittance was measured with a conventional slit-grid measurement device. The goal was to measure the beam emittance at high-beam currents. The article will give a detailed description of the measurement of a 56 mA beam at 26 keV with 85% protons. Theoretical considerations of the emittance value, given by ion temperature and aberrations of the extraction system, allows an estimation of the emittance of a 170 mA at 55 keV proton beam. In a second step, an estimation of a postaccelerated 140 mA at 100 keV deuteron beam was completed. © 2002 American Institute of Physics.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 44 (1974), S. 69-72 
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung In der vorliegenden Arbeit werden die Karyotypen von zwei röntgeninduzierten Formen von Pisum sativum dargestellt und mit dem Karyotyp der Ausgangsform ‘Dippes gelbe Viktoria’ verglichen. Die zytologische Analyse erbrachte deutliche Unterschiede zwischen der Vergleichsform und diesen beiden Linien, die auf jeweils eine einfache reziproke Translokation zurückgeführt werden konnten. In beiden Fällen waren Satelliten-Chromosomen an dem Austauschprozeß beteiligt. Bei 62B erfolgte eine Translokation zwischen dem langen Arm von Chromosom V und dem satellitentragenden langen Arm von VII. Die Linie 488 entstand durch Austausch zwischen den beiden Satelliten-Chromosomen IV und VII, und zwar in der Weise, daß ein sehr kleines satellitenfreies und ein sehr langes Chromosom gebildet wurde, welches an den Enden seiner etwa gleich langen Arme jeweils einen Satelliten trägt. Die Vereinigung der beiden Satelliten-Regionen in einem Chromosom ist bisher für Pisum noch nicht beschrieben worden. Zum Schluß wurde kurz die Bedeutung diskutiert, die solche drastischen Veränderungen des Karyotyps für die züchterische Praxis und für evolutionistische Fragestellungen haben könnten.
    Notes: Summary In connection with X-ray experiments on Pisum sativum ‘Dippes gelbe Victoria’, two translocation line showing dramatic deviations from the normal karyotype were selected and cytologically analysed (root tips). In line 62B, an exchange between the long arms of chromosome V and the satellite chromosome VII took place. In line 488, both satellite chromosomes IV and VII were involved in the exchange process, leading to a very short chromosome (VII T!), and a very long chromosome (IV T!) uniting both the satellites in one chromosome. The importance of these lines with regard to mutation breeding and evolution is discussed.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 57 (1970), S. 456-456 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 31 (1943), S. 277-278 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
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  • 6
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 33 (2000), S. 1162-1174 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The instrumental transparency functions of five commercially available texture goniometers were measured experimentally with six monocrystalline samples cut in different orientations from a large highly perfect silicon crystal with a rocking curve of less than 0.01°. Transparency functions were measured in steps of 0.02 to 0.2° in the pole-figure angles α, β. The window size Δα depends on the Bragg angle θ in the form 1/sinθ; the window size Δω is constant for each goniometer. The dominant instrumental parameter determining the long axis Δα of the pole-figure window is the axial width of the detector entrance slit. This parameter is smallest for area detectors (smaller by more than an order of magnitude compared with conventional scintillation detectors as well as one-dimensional position-sensitive detectors). The main features of the pole-figure window and their dependence on the instrumental parameters can be deduced fairly well from a simple geometrical model. The particular shapes of the transparency functions of the studied goniometers are markedly different. Particularly, they are not very well represented by Gauss functions. The two-dimensional transparency function can be fairly well characterized by its α and β profiles. The normalized profiles are virtually independent of the goniometer angles 2θ and α. The increasing size of the pole-figure window with decreasing θ puts a lower limit on the Bragg angle below which pole-figure measurement ceases to be meaningful.
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 226 (1970), S. 1029-1033 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In vitro studies using antisera to each of the two E. coli release factors, R1 and R2, show that these factors mediate release of complete proteins. Either factor can terminate R17 coat protein or R17 RNA ...
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 27 (1971), S. 399-399 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary InSylvia borin andS. atricapilla, circannual rhythmicity was found in moult, migratory restlessness and in changes of body weight and gonad size under constant photoperiodic conditions.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Chromosoma 37 (1972), S. 223-231 
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Three mutants of Pisum sativum showing anomalies in the conjugation phase of meiosis, were investigated cytogenetically. Inspite of apparent normal chromosome pairing there is a strong reduction of chiasma number resulting into univalent formation. Simultaneously, chromosome aberrations appear as consequence of breakage and reunions in the prophase stage. The combined occurrence of these anomalies and their respective quantitative relationships to each other have been explained in the light of “breakage-reunion hypothesis” through the action of following factors: pairing behaviour, breakage frequency, number of breakages at one locus in the chromatid tetrads, behaviour of breakage ends and effects of environment. Due to the interaction of these factors all the anomalies found in our mutants are explainable.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 22 (1970), S. 84-84 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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