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Search Results: 1 - 10 of 84406 matches for " W. Potzel "
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Recoilless Resonant Emission and Detection of Electron Antineutrinos
Potzel, W.
High Energy Physics - Phenomenology , 2008, DOI: 10.1088/1742-6596/136/2/022010
Abstract: Recoilless resonant capture of monoenergetic electron antineutrinos (Moessbauer antineutrinos) emitted in bound-state beta-decay in the system 3H - 3He is discussed. The recoilfree fraction including a possible phonon excitation due to local lattice expansion and contraction at the time of the nuclear transition, homogeneous and inhomogeneous line broadening, and the relativistic second-order Doppler effect are considered. It is demonstrated that homogeneous line broadening is essential due to stochastic magnetic relaxation processes in a metallic lattice. Inhomogeneous line broadening plays an equally important role. An essential issue which has been overlooked up to now, is an energy shift of the resonance line due to the direct influence of the binding energies of the 3H and 3He atoms in the lattice on the energy of the electron antineutrinos. This energy shift as well as the second-order Doppler shift exhibit variations in a non-perfect (inhomogeneous) lattice and may seriously jeopardize the observation of Moessbauer antineutrinos. If successful in spite of these enormous difficulties, Moessbauer antineutrino experiments could be used to gain new and deep insights into the nature of neutrino oscillations, determine the neutrino mass hierarchy as well as up to now unknown oscillation parameters, search for sterile neutrinos, and measure the gravitational redshift of electron antineutrinos in the field of the Earth.
Clock Hypothesis of Relativity Theory, Maximal Acceleration, and M?ssbauer Spectroscopy
W. Potzel
Physics , 2014,
Abstract: Results obtained several years ago using the high-resolution 93.3 keV M\"ossbauer resonance in $^{67}$ZnO and $\beta'$-brass have been reanalyzed with the notion that the clock hypothesis of Special Relativity Theory is not sufficient, but that a maximal acceleration $a_m$ exists and that an acceleration $a$ contributes to the temperature dependence of the center shift by a term $\pm(1/2)(a/a_m)^2$. The significance of the sign of this term is discussed in detail. For both substances a lower limit of $a_m>1.5\cdot10^{21}m/s^2$ is inferred which is more than two orders of magnitude larger than the value $a_m=1\cdot10^{19}m/s^2$ suggested by $^{57}$Fe rotor experiments.
Recoilless resonant neutrino experiment and origin of neutrino oscillations
Bilenky, S. M.;von Feilitzsch, F.;Potzel, W.
High Energy Physics - Phenomenology , 2007, DOI: 10.1063/1.2818539
Abstract: We demonstrate that an experiment with recoilless resonant emission and absorption of tritium antineutrinos could have an important impact on our understanding of the origin of neutrino oscillations.
Implications of the SNO and the Homestake Results for the BOREXINO Experiment
S. M. Bilenky,T. Lachenmaier,W. Potzel,F. von Feilitzsch
Physics , 2001,
Abstract: Using the recent result of the SNO solar neutrino experiment, we have demonstrated in a model independent way that the contribution of Be-7 and other medium energy neutrinos to the event rate of the Homestake experiment is 4 sigma smaller than the BP2000 SSM prediction. We have considered the implications of this result for the future BOREXINO experiment.
Moessbauer antineutrinos: some basic considerations
Walter Potzel
Physics , 2009,
Abstract: Basic aspects of phononless resonant capture of monoenergetic electron antineutrinos (Moessbauer antineutrinos) emitted in boundstate beta-decay in the 3H - 3He system are considered. It is shown that stochastic magnetic relaxation phenomena as well as the direct influence of solid-state effects on the energy of the electron antineutrino will cause line broadening by a factor of more than 10^(13). Lattice expansion and contraction after the transformation of the nucleus will drastically reduce the probability for phononless transitions. Thus, the observation of Moessbauer electron antineutrinos of the 3H - 3He system will most probably be unsuccessful. As a possible alternative, the Rare-Earth system 163Ho - 163Dy is briefly discussed.
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.
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.
Microscopic Model for the Scintillation-Light Generation and Light-Quenching in CaWO$_4$ single crystals
S. Roth,F. v. Feilitzsch,J. -C. Lanfranchi,W. Potzel,S. Sch?nert,A. Ulrich
Physics , 2015,
Abstract: Scintillators are employed for particle detection and identification using light-pulse shapes and light quenching factors. We developed a comprehensive model describing the light generation and quenching in CaWO$_4$ single crystals used for direct dark matter search. All observed particle-dependent light-emission characteristics can be explained quantitatively, light-quenching factors and light-pulse shapes are calculated on a microscopic basis. This model can be extended to other scintillators such as inorganic crystal scintillators, liquid noble gases or organic liquid scintillators.
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.
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