495 research outputs found
Sigmund Freud contra Helga Grebing - Kommentierende Anmerkungen zu den Beiträgen von Max Bloch, Karsten Rudolph, Meik Woyke und Walter Mühlhausen
No full textConcentrating on the contributions of Max Bloch, Karsten Rudolph, Meik Woyke and Walter Mühlhausen the author sums up the contributions of this volume in order to reflect on the current state of research in the field of the historiography of biographies of leading social democrats. He discusses remaining lacunae in research and develops perspectives for future research
The importance of the beta spectrum calculation for accurate activity determination of 63 Ni by means of liquid scintillation counting
No full textInternational audienceThe activity concentration of a Ni-63 solution was determined by means of two liquid scintillation counting techniques: the TDCR method and the CIEMAT/NIST efficiency tracing technique. The results of both methods are in excellent agreement, provided that the Ni-63 beta spectrum calculation accounts for the atomic exchange effect. Thus, new beta spectrum calculations resolve a discrepancy that has been found in previous analyses. The influence of the computed beta spectrum on the final uncertainty of the activity concentration is discussed
Improved activity standardization of Sr/Y by means of liquid scintillation counting
No full textInternational audienceRadioactive strontium isotopes play an important role in environmental radioactivity. Reliable activity standards are required in order to validate radioanalytical techniques and related measurements. In this paper, improved methods for the primary activity standardization of Sr/Y based on liquid scintillation counting are presented. To this end, two methods were used: the CIEMAT/NIST efficiency tracing technique with 3H as a tracer and the triple-to-double coincidence ratio method. Non-negligible discrepancies between the two methods were found when applying existing analysis techniques. A detailed study was carried out to identify and eliminate the causes of these discrepancies.Eventually, excellent agreement between the two methods was obtained. This required advanced beta spectrum calculations which were carried out with a specific version of the BetaShape program taking the atomic exchange effect into account. In addition, it was found that the quench-indicating parameters determined in commercial liquid scintillation counters are biased, which can cause significant problems for the CIEMAT/NIST efficiency tracing method. The effect depends on the counting rate and can be explained by a superposition of the LS spectra generated by Sr/Y and the external standard source
B --> ([rho]/[omega]) [gamma] at BaBar
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2007.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.In title on title page, "[right arrow] appears as the symbol; and "[rho]", "[omega]" and "[gamma]" appear as lower-case Greek letters.Includes bibliographical references (leaves 203-205).This document describes the measurements of the branching fractions and isospin violations of the radiative electroweak penguin decays B [right arrow] ([rho]/[omega]) [gamma] at the asymmetric energy e+e- PEP-II collider with the BABAR detector. Together with the previously measured branching fractions of the decays ... the ratio of CKM-matrix elements Vtd=Vts are extracted and the length of the far side of the unitarity triangle is determined.by Karsten Köneke.Ph.D
Do radioactive decay rates depend on the distance between the Earth and the Sun?
No full textThe potential influence of solar neutrinos on beta decay rates was investigated at PTB. To this end, new experiments have been carried out for the beta emitters \nuc{36}{Cl} and \nuc{90}{Sr}/\nuc{90}{Y}, respectively. The measurements were performed using custom-built liquid scintillation counters with three photomultiplier tubes (PMTs). The data were analyzed applying the TDCR method which yields information on the counting efficiency and the activity. The activities corrected for decay were found to be stable and no oscillation could be observed. Also frequency analyses do not show any significant periodicity. Thus, we disprove the findings from several previous works of a research group working with Fischbach, Jenkins, Sturrock et al. who used data from relative measurement methods only. The data they use are not suitable to claim evidence for variations of decay rates, since the measurement techniques do not provide information on the instrument efficiency. That group also used data from our laboratory which were obtained by means of ionization chambers. We can show that the observed effects cannot be explained with an influence of solar neutrinos, whereas an influence of climate data in the corresponding measurement room appears to be a more plausible reason
Ionisierende Strahlung in der Medizin (Auszug aus: PTB-Mitteilungen 2013, Band 123, Heft 2. ISSN 0030-834X)
No full textPTB-Mitteilungen. Band 123 (2013), Heft 2, Seite 1 - 81. ISSN 0030-834X1.:
Janßen, Herbert: Vorwort
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Ankerhold, Ulrike: Ionisierende Strahlung in Diagnostik und Therapie
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Büermann, Ludwig: Metrologische Aspekte der Dosimetrie in der Röntgendiagnostik
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Kossert, Karsten: Aktivitätsbestimmung von Radionukliden für Diagnostik und Therapie
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Ankerhold, Ulrike und Thorsten Schneider: Dosimetrie für die Brachytherapie
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Krauss, Achim: Kalorimetrische Bestimmung der Wasser-Energiedosis
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Kapsch, Ralf-Peter: Dosimetrie mit Ionisationskammern in der externen Strahlentherapie
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Anton, Mathias: Dosimetrie für die externe Strahlentherapie: Dosimetrie mit Alanin
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Ambrosi, Peter: Strahlenschutz in der Medizin
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Hupe, Oliver: Messgeräte und Herausforderungen in der Strahlenschutzmesstechnik
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Ambrosi,Peter, Oliver Hupe und H.-M. Kramer: Messgrößen im Strahlenschutz
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Hupe, Oliver: Amtliche Personendosimetrie für Medizin-Personal
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Hupe, Oliver: Dosis für helfende Personen in der Human-, Zahn- und Tiermedizin
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Behrens, Rolf: Teilkörperdosimetrie für Photonen und Betastrahlung
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Hupe, Oliver, Hayo Zutz und Peter Ambrosi: Elektronische Dosimeter für gepulste Strahlung
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Zutz, Hayo: Messung der Strahlung im Beschleuniger-Therapieraum
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Hans Rabus: Strahlenwirkung
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Arndt, Alexander und Woon Yong Baek: Strahlenwirkung auf Biomoleküle
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Bug, Marion und Heidi Nettelbeck: Simulation der Strahlenwirkung auf biologische Objekte
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Hilgers, Gerhard: Messung der Spurstruktur ionisierender Strahlung
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Giesen, Ulrich: Strahlenwirkung auf zellulärer Eben
Improved method for the calculation of the counting efficiency of electron-capture nuclides in liquid scintillation samples
No full textThe methods to compute the counting efficiency of electron-capture nuclides in liquid scintillation counting have been improved in several previous studies. The main improvements comprise a more realistic treatment of the ejection of photoelectrons and subsequent rearrangement processes in the atomic shell as well as a more detailed atomic rearrangement model. The latter was realized in the MICELLE code by means of a new stochastic approach. This new model was also developed to account for energy deposits within micelles.The recent improvements have now been combined in an updated version of the MICELLE code, which also makes the computation of the counting efficiency of complex decay schemes possible.In this paper, we describe and discuss recent extensions and improvements of the models and further corrections. The calculated counting efficiencies of selected radionuclides are compared with the experimental data obtained by liquid scintillation counting. For the measurements, we use standard solutions, which were calibrated by other methods. © 2009 Elsevier Ltd.Peer Reviewe
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