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Search Results: 1 - 10 of 208450 matches for " L. Oberauer "
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Light Concentrators for Borexino and CTF
L. Oberauer,C. Grieb,F. von Feilitzsch,I. Manno
Physics , 2003, DOI: 10.1016/j.nima.2004.05.095
Abstract: Light concentrators for the solar neutrino experiment Borexino and the Counting Test Facility (CTF) have been developed and constructed. They increase the light yield of these detectors by a factor of 2.5 and 8.8, respectively. Technical challenges like long term stability in various media, high reflectivity and radiopurity have been addressed and the concepts to overcome these difficulties will be described. Gamma spectroscopy measurements of the concentrators show an upper limit of 12e-6 Bq/g for uranium and a value of 120e-6 Bq/g for thorium. Upper limits on other possible contaminations like 26Al are presented. The impact of these results on the performance of Borexino and the CTF are discussed and it is shown that the design goals of both experiments are fulfilled.
Fluorescence decay-time constants in organic liquid scintillators
T. Marrodan Undagoitia,F. von Feilitzsch,L. Oberauer,W. Potzel,A. Ulrich,J. Winter,M. Wurm
Physics , 2009, DOI: 10.1063/1.3112609
Abstract: The fluorescence decay-time constants have been measured for several scintillator mixtures based on phenyl-o-xylylethane (PXE) and linear alkylbenzene (LAB) solvents. The resulting values are of relevance for the physics performance of the proposed large-volume liquid scintillator detector LENA (Low Energy Neutrino Astronomy). In particular, the impact of the measured values to the search for proton decay via p -> K+ antineutrino is evaluated in this work.
Spectroscopy of electron-induced fluorescence in organic liquid scintillators
T. Marrodan Undagoitia,F. von Feilitzsch,L. Oberauer,W. Potzel,A. Ulrich,J. Winter,M. Wurm
Physics , 2010, DOI: 10.1140/epjd/e2010-00004-1
Abstract: Emission spectra of several organic liquid-scintillator mixtures which are relevant for the proposed LENA detector have been measured by exciting the medium with electrons of ~10keV. The results are compared with spectra resulting from ultraviolet light excitation. Good agreement between spectra measured by both methods has been found.
Re-publication of the data from the BILL magnetic spectrometer: The cumulative $β$ spectra of the fission products of $^{235}$U, $^{239}$Pu, and $^{241}$Pu
N. Haag,W. Gelletly,F. von Feilitzsch,L. Oberauer,W. Potzel,K. Schreckenbach,A. A. Sonzogni
Physics , 2014,
Abstract: In the 1980s, measurements of the cumulative $\beta$ spectra of the fission products following the thermal neutron induced fission of $^{235}$U, $^{239}$Pu, and $^{241}$Pu were performed at the magnetic spectrometer BILL at the ILL in Grenoble. This data was published in bins of 250 keV. In this paper, we re-publish the original data in a binning of 50 keV for $^{235}$U and 100 keV for $^{239}$Pu and $^{241}$Pu.
Experimental Determination of the Antineutrino Spectrum of the Fission Products of $^{238}$U
N. Haag,A. Gütlein,M. Hofmann,L. Oberauer,W. Potzel,K. Schreckenbach,F. M. Wagner
Physics , 2013, DOI: 10.1103/PhysRevLett.112.122501
Abstract: An experiment was performed at the scientific neutron source FRM II in Garching to determine the cumulative antineutrino spectrum of the fission products of $^{238}$U. This was achieved by irradiating target foils of natural uranium with a thermal and a fast neutron beam and recording the emitted $\beta$-spectra with a gamma-suppressing electron-telescope. The obtained $\beta$-spectrum of the fission products of $^{235}$U was normalized to the data of the magnetic spectrometer BILL of $^{235}$U. This method strongly reduces systematic errors in the $^{238}$U measurement. The $\beta$-spectrum of $^{238}$U was converted into the corresponding antineutrino spectrum. The final $\bar\nu_e$-spectrum is given in 250 keV bins in the range from 2.875 MeV to 7.625 MeV with an energy-dependent error of 3.5 % at 3 MeV, 7.6 % at 6 MeV and $\gtrsim$ 14 % at energies $\gtrsim$ 7 MeV (68 % confidence level). Furthermore, an energy-independent uncertainty of $\sim$ 3.3 % due to the absolute normalization is added. Compared to the generally used summation calculations, the obtained spectrum reveals a slight spectral distortion of $\sim$ 10 % but returns the same value for the mean cross section per fission for the inverse beta decay.
Attenuation of vacuum ultraviolet light in pure and xenon-doped liquid argon - an approach to an assignment of the near-infrared emission from the mixture
A. Neumeier,T. Dandl,A. Himpsl,L. Oberauer,W. Potzel,S. Sch?nert,A. Ulrich
Physics , 2015, DOI: 10.1209/0295-5075/111/12001
Abstract: Results of transmission experiments of vacuum ultraviolet light through a 11.6 cm long cell filled with pure and xenon-doped liquid argon are described. Pure liquid argon shows no attenuation down to the experimental short-wavelength cut-off at 118nm. Based on a conservative approach, a lower limit of 1.10 m for the attenuation length of its own scintillation light could be derived. Adding xenon to liquid argon at concentrations on the order of parts per million leads to strong xenon-related absorption features which are used for a tentative assignment of the recently found near-infrared emission observed in electron-beam excited liquid argon-xenon mixtures. Two of the three absorption features can be explained by perturbed xenon transitions and the third one by a trapped exciton (Wannier-Mott) impurity state. A calibration curve connecting the equivalent width of the absorption line at 140 nm with xenon concentration is provided.
Attenuation measurements of vacuum ultraviolet light in liquid argon revisited
A. Neumeier,T. Dandl,A. Himpsl,M. Hofmann,L. Oberauer,W. Potzel,S. Sch?nert,A. Ulrich
Physics , 2015, DOI: 10.1016/j.nima.2015.07.051
Abstract: The attenuation of vacuum ultraviolet light in liquid argon in the context of its application in large liquid noble gas detectors has been studied. Compared to a previous publication several technical issues concerning transmission measurements in general are addressed and several systematic effects were quantitatively measured. Wavelength-resolved transmission measurements have been performed from the vacuum ultraviolet to the near-infrared region. On the current level of sensitivity with a length of the optical path of 11.6 cm, no xenon-related absorption effects could be observed, and pure liquid argon is fully transparent down to the short wavelength cut-off of the experimental setup at 118 nm. A lower limit for the attenuation length of pure liquid argon for its own scintillation light has been estimated to be 1.10 m based on a very conservative approach.
Attenuation of vacuum ultraviolet light in liquid argon
A. Neumeier,M. Hofmann,L. Oberauer,W. Potzel,S. Sch?nert,T. Dandl,T. Heindl,A. Ulrich,J. Wieser
Physics , 2015, DOI: 10.1140/epjc/s10052-012-2190-z
Abstract: The transmission of liquid argon has been measured, wavelength resolved, for a wavelength interval from 118 to 250 nm. The wavelength dependent attenuation length is presented for pure argon. It is shown that no universal wavelength independent attenuation length can be assigned to liquid argon for its own fluorescence light due to the interplay between the wavelength dependent emission and absorption. A decreasing transmission is observed below 130 nm in both chemically cleaned and distilled liquid argon and assigned to absorption by the analogue of the first argon excimer continuum. For not perfectly cleaned argon a strong influence of impurities on the transmission is observed. Two strong absorption bands at 126.5 and 141.0 nm with approximately 2 and 4 nm width, respectively, are assigned to traces of xenon in argon. A broad absorption region below 180 nm is found for unpurified argon and tentatively attributed to the presence of water in the argon sample.
The scintillation of liquid argon
T. Heindl,T. Dandl,M. Hofmann,R. Krücken,L. Oberauer,W. Potzel,J. Wieser,A. Ulrich
Physics , 2015, DOI: 10.1209/0295-5075/91/62002
Abstract: A spectroscopic study of liquid argon from the vacuum ultraviolet at 110 nm to 1000 nm is presented. Excitation was performed using continuous and pulsed 12 keV electron beams. The emission is dominated by the analogue of the so called 2nd excimer continuum. Various additional emission features were found. The time structure of the light emission has been measured for a set of well defined wavelength positions. The results help to interpret literature data in the context of liquid rare gas detectors in which the wavelength information is lost due to the use of wavelength shifters.
Table-top setup for investigating the scintillation properties of liquid argon
T. Heindl,T. Dandl,A. Fedenev,M. Hofmann,R. Krücken,L. Oberauer,W. Potzel,J. Wieser,A. Ulrich
Physics , 2015, DOI: 10.1088/1748-0221/6/02/P02011
Abstract: The spectral and temporal light emission properties of liquid argon have been studied in the context of its use in large liquid rare-gas detectors for detecting Dark Matter particles in astronomy. A table-top setup has been developed. Continuous and pulsed low energy electron beam excitation is used to stimulate light emission. A spectral range from 110 to 1000 nm in wavelength is covered by the detection system with a time resolution on the order of 1 ns.
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