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Search Results: 1 - 10 of 325483 matches for " S. Kraft-Bermuth "
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Investigation of peak shapes in the MIBETA experiment calibrations
E. Ferri,S. Kraft-Bermuth,A. Monfardini,A. Nucciotti,D. Schaeffer,M. Sisti
Physics , 2012, DOI: 10.1140/epja/i2012-12131-5
Abstract: In calorimetric neutrino mass experiments, where the shape of a beta decay spectrum has to be precisely measured, the understanding of the detector response function is a fundamental issue. In the MIBETA neutrino mass experiment, the X-ray lines measured with external sources did not have Gaussian shapes, but exhibited a pronounced shoulder towards lower energies. If this shoulder were a general feature of the detector response function, it would distort the beta decay spectrum and thus mimic a non-zero neutrino mass. An investigation was performed to understand the origin of the shoulder and its potential influence on the beta spectrum. First, the peaks were fitted with an analytic function in order to determine quantitatively the amount of events contributing to the shoulder, also depending on the energy of the calibration X-rays. In a second step, Montecarlo simulations were performed to reproduce the experimental spectrum and to understand the origin of its shape. We conclude that at least part of the observed shoulder can be attributed to a surface effect.
The Philippines: The Weak State and the Global War on Terror
Herman Joseph S. Kraft
Kasarinlan : Philippine Journal of Third World Studies , 2003,
Abstract: The Philippines is clearly one of the principal “front-line” states with Southeast Asia’s identification as the second front of the “global war on terror.” Its participation in and strong support for this campaign was commended strongly in the international stage especially by the government of the United States. At the same time, however, this policy was received with mixed feelings within the country itself. There are strong and legitimate fears that the Philippine government’s support for the United States places the stability of the country over the short- to medium-term in jeopardy. This is particularly important as the international campaign against terror has come at an inopportune time. The Philippines is currently facing multi-faceted challenges that the government is unable to address because it cannot mobilize the requisite economic and political resources. Terrorism is not the main cause of the persistent instability in the Philippines. The growth and persistence of terrorism in the country, in fact, is indicative of the weak Philippine state.
Bilateralism in the Changing Asia-Pacific Environment
Herman Joseph S. Kraft
Kasarinlan : Philippine Journal of Third World Studies , 1995,
Abstract: The Security structure of the Asia-Pacific during the Cold War is characterized by a web of interlocking bilateral alliances woven by the United States. Through this ‘hub and spokes’ mechanism, American influence in the region was guaranteed as states dealt with one another by means of their respective bilateral linkages with Washington. This arrangement effectively prevented regional states and actors from challenging the hegemony of the United States over the conduct of regional security affairs.The end of the Cold War, the consequent decline of American military presence in the region, and the emergence of new geostrategic players have made this network of bilateral alliances inadequate, if not outdated, for the complex and uncertain post-Cold War international system. This, in turn, necessitates a rethinking of bilateralism and its place in the new regional security environment. With Philippine-United States Relations as backdrop, it is argued that until multilateral mechanisms are designated to help diffuse crises and, in conditions of conflict, actually enforced the uneven distribution of power among states will continue to provide the reason for small states to seek the assistance of stronger states through bilateral security arrangement. Bilateral alliances with neighbors and other regional actors, should therefore, be enhanced with the view of complementing multilateral efforts towards security cooperation. In the last analysis, however, while bilateralism remains an important aspect of Asia Pacific security, a collective effort is indispensable for ensuring regional stability.
China and Democracy in the Asia Pacific
Herman Joseph S. Kraft
UNISCI Discussion Papers , 2006,
Middle Ordovician graptolite fauna from Praha - erveny vrch (Prague Basin, Czech Republic)
Kraft P,Kraft J
Bulletin of Geosciences , 2003, DOI: 10.3140/bull.geosci.2003.02.129
Abstract: Graptolites collected from a section of the árka Formation at Praha - erveny vrch indicate the uppermost Arenigian (lower part of the Corymbograptus retroflexus Biozone). The pendent Didymograptus cf. spinulosus indicating the Llanvirnian age is recorded from this locality. It is evident that the graptolite faunas span the Arenigian/Llanvirnian boundary interval. Thirteen species of graptolites including seven graptoloid species were found. The succession of graptolite assemblages is compared with the measured section at Rokycany - Drahou used here as a standard for this interval. The data set from Praha - erveny vrch indicates overthrusting within this section of the árka Formation.
Spatially resolved photo ionization of ultracold atoms on an atom chip
S. Kraft,A. Günther,J. Fortágh,C. Zimmermann
Physics , 2007, DOI: 10.1103/PhysRevA.75.063605
Abstract: We report on photo ionization of ultracold magnetically trapped Rb atoms on an atom chip. The atoms are trapped at 5 $\mu $K in a strongly anisotropic trap. Through a hole in the chip with a diameter of 150 $\mu $m two laser beams are focussed onto a fraction of the atomic cloud. A first laser beam with a wavelength of 778 nm excites the atoms via a two photon transition to the 5D level. With a fiber laser at 1080 nm the excited atoms are photo ionized. Ionization leads to depletion of the atomic density distribution observed by absorption imaging. The resonant ionization spectrum is reported. The setup used in this experiment is not only suitable to investigate BEC ion mixtures but also single atom detection on an atom chip.
Characterising a Si(Li) detector element for the SIXA X-ray spectrometer
T. Tikkanen,S. Kraft,F. Scholze,R. Thornagel,G. Ulm
Physics , 1997, DOI: 10.1016/S0168-9002(97)00473-7
Abstract: The detection efficiency and response function of a Si(Li) detector element for the SIXA spectrometer have been determined in the 500 eV to 5 keV energy range using synchrotron radiation emitted at a bending magnet of the electron storage ring BESSY, which is a primary radiation standard. The agreement between the measured spectrum and the model calculation is better than 2%. PACS: 95.55.Ka; 07.85.Nc; 29.40.Wk; 85.30.De Keywords: Si(Li) detectors, X-ray spectrometers, detector calibration, X-ray response, spectral lineshape
Bose-Einstein Condensates in Magnetic Waveguides
J. Fortagh,H. Ott,S. Kraft,A. Guenther,C. Zimmermann
Physics , 2002, DOI: 10.1007/s00340-003-1107-9
Abstract: In this article, we describe an experimental system for generating Bose-Einstein condensates and controlling the shape and motion of the condensate by using miniaturised magnetic potentials. In particular, we describe the magnetic trap setup, the vacuum system, the use of dispenser sources for loading a high number of atoms into the magneto-optical trap, the magnetic transfer of atoms into the microtrap, and the experimental cycle for generating Bose-Einstein condensates. We present first results on outcoupling of condensates into a magnetic waveguide and discuss influences of the trap surface on the ultracold ensembles.
Surface Effects in Magnetic Microtraps
J. Fortagh,H. Ott,S. Kraft,C. Zimmermann
Physics , 2002, DOI: 10.1103/PhysRevA.66.041604
Abstract: We have investigated Bose-Einstein condensates and ultra cold atoms in the vicinity of a surface of a magnetic microtrap. The atoms are prepared along copper conductors at distances to the surface between 300 um and 20 um. In this range, the lifetime decreases from 20 s to 0.7 s showing a linear dependence on the distance to the surface. The atoms manifest a weak thermal coupling to the surface, with measured heating rates remaining below 500 nK/s. In addition, we observe a periodic fragmentation of the condensate and thermal clouds when the surface is approached.
Phase coherent splitting of Bose-Einstein condensates with an integrated magnetic grating
A. Günther,S. Kraft,C. Zimmermann,J. Fortágh
Physics , 2006, DOI: 10.1103/PhysRevLett.98.140403
Abstract: We report the phase coherent splitting of Bose-Einstein condensates by means of a phase grating produced near the surface of a micro-electronic chip. A lattice potential with a period of $4\mu$m is generated by the superposition of static and oscillating magnetic fields. Precise control of the diffraction is achieved by controlling the currents in the integrated conductors. The interference of overlapping diffraction orders is observed after 8ms of propagation in a harmonic trap and subsequent ballistic expansion of the atomic ensemble. By analyzing the interference pattern we show a reproducible phase relation between the diffraction orders with an uncertainty given by the resolution of the diffraction grating.
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