14,107 research outputs found
On the determination of anti-neutrino spectra from nuclear reactors
In this paper we study the effect of, well-known, higher order corrections to
the allowed beta decay spectrum on the determination of anti-neutrino spectra
resulting from the decays of fission fragments. In particular, we try to
estimate the associated theory errors and find that induced currents like weak
magnetism may ultimately limit our ability to improve the current accuracy and
under certain circumstance could even largely increase the theoretical errors.
We also perform a critical evaluation of the errors associated with our method
to extract the anti-neutrino spectrum using synthetic beta spectra. It turns
out, that a fit using only virtual beta branches with a judicious choice of the
effective nuclear charge provides results with a minimal bias. We apply this
method to actual data for U235, Pu239 and Pu241 and confirm, within errors,
recent results, which indicate a net 3% upward shift in energy averaged
anti-neutrino fluxes. However, we also find significant shape differences which
can in principle be tested by high statistics anti-neutrino data samples.Comment: 20 pages, 5 figures, 9 tables, added references, version accepted for
publication in Phys. Rev. C. Corrected errors in tab. 1 and eqs. 18 and 19.
Results and conclusion unchange
Periodic boundary conditions for the simulation of 3D domain patterns in tetragonal ferroelectric material
Periodic domain patterns in tetragonal ferroelectrics are explored using a phase field model calibrated for barium titanate. In this context, we discuss the standard periodic boundary condition and introduce the concept of reverse periodic boundary conditions. Both concepts allow the assembly of cubic cells in accordance with mechanical and electrical conditions. However, application of the reverse periodic boundary condition is due to an increased size of the RVE and enforces more complex structures compared to the standard condition. This may be of particular interest for other multiphysics simulations. Additionally, we formulate mechanical side conditions with minimal spherical (hydrostatic) stress, or conditions with controlled average strain. It is found that in sufficiently small periodic cells, only a uniform single domain, or the simplest stripe domains constitute equilibrium states. However, once the periodic cells are of order 20 domain wall widths in size, more complex, 3-dimensional patterns emerge. Some of these patterns are known from prior studies, but we also identify other domain patterns with long, ribbon-like domains threaded through them and some vortex-like structures. Keywords: Periodic boundary conditions; RVE simulation; Tetragonal ferroelectrics; Polarization patterns; Polarization vortex; Multiphysics simulation
Cavity QED in a molecular ion trap
We propose an approach for studying quantum information and performing high
resolution spectroscopy of rotational states of trapped molecular ions using an
on-chip superconducting microwave resonator. Molecular ions have several
advantages over neutral molecules. Ions can be loaded into deep (1 eV) RF traps
and are trapped independent of the electric dipole moment of their rotational
transition. Their charge protects them from motional dephasing and prevents
collisional loss, allowing 1 s coherence times when used as a quantum memory,
with detection of single molecules possible in <10 ms. An analysis of the
detection efficiency and coherence properties of the molecules is presented.Comment: 9 pages, 1 figur
Measurement Parameter Optimization for Surface Crack Detection in Metals using an Open-Ended Waveguide Probe
Fatigue and stress induced surface crack detection in metals is an important practical issue. A newly developed microwave inspection approach, using an open-ended rectangular waveguide, has proved to be an effective tool for detecting such cracks. This novel microwave approach overcomes some of the limitations associated with the standard detection methods for surface crack detection. In addition, this approach is applicable to exposed, filled (with a dielectric such as dirt, rust, etc.) and cracks under dielectric coatings such as paint. This paper presents the basic foundation of this surface crack detection methodology along with the ways by which measurement parameters may be optimized for increased detection sensitivity
FPGA based data acquisition system for COMPASS experiment
This paper discusses the present data acquisition system (DAQ) of the COMPASS
experiment at CERN and presents development of a new DAQ. The new DAQ must
preserve present data format and be able to communicate with FPGA cards. Parts
of the new DAQ are based on state machines and they are implemented in C++ with
usage of the QT framework, the DIM library, and the IPBus technology. Prototype
of the system is prepared and communication through DIM between parts was
tested. An implementation of the IPBus technology was prepared and tested. The
new DAQ proved to be able to fulfill requirements.Comment: 8 pages, CHEP 201
Identification of a non-purple tartrate-resistant acid phosphatase: an evolutionary link to Ser/Thr protein phosphatases?
Rotational cooling of heteronuclear molecular ions with ^1-Sigma, ^2-Sigma, ^3-Sigma and ^2-Pi electronic ground states
The translational motion of molecular ions can be effectively cooled
sympathetically to translational temperatures below 100 mK in ion traps through
Coulomb interactions with laser-cooled atomic ions. The ro-vibrational degrees
of freedom, however, are expected to be largely unaffected during translational
cooling. We have previously proposed schemes for cooling of the internal
degrees of freedom of such translationally cold but internally hot
heteronuclear diatomic ions in the simplest case of ^1-Sigma electronic ground
state molecules. Here we present a significant simplification of these schemes
and make a generalization to the most frequently encountered electronic ground
states of heteronuclear molecular ions: ^1-Sigma, ^2-Sigma, ^3-Sigma and ^2-Pi.
The schemes are relying on one or two laser driven transitions with the
possible inclusion of a tailored incoherent far infrared radiation field.Comment: 16 pages, 13 figure
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