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Volumetric Calibration Refinement using masked back projection and image correlation superposition
This paper deals with a new, reconstruction based, approach of refining a volumetric calibration. The technique is based on a 2D cross-correlation between particle images on the sensor plane with a planar back projection from a tomographic reconstruction in the same sensor plane to determine potential disparities between the initial camera calibration and the measurement. Additive superposition of the correlation maps from different sets or particle images allows reducing the influence of noise and ghost particles such that the systematic errors in the calibration can be corrected. The different sections describe the theory, the principle processing steps and the convergence of the procedure. Furthermore, the concept is proven by simulating the entire process of the measurement chain, with the help of a synthetic comparison. The results show that disparities of over 9 pixels could be corrected to an average of below 0.1 pixels during the refinement steps. Finally, the technique demonstrates it´s potential to measured data, where the numbers of outliers in the raw results are reduced after the volumetric calibration refinement
Particle-level pileup subtraction for jets and jet shapes
We present an extension to the jet area-based pileup subtraction for both jet
kinematics and jet shapes. A particle-level approach is explored whereby the
jet constituents are corrected or removed using an extension of the methods
currently being employed by the LHC experiments. Several jet shapes and nominal
jet radii are used to assess the performance in simulated events with pileup
levels equivalent to approximately 30 and 100 interactions per bunch crossing,
which are characteristic of both the LHC Run I and Run II conditions. An
improved performance in removing the pileup contributions is found when using
the new subtraction method. The performance of the new procedure is also
compared to other existing methods
Improved microscopic-macroscopic approach incorporating the effects of continuum states
The Woods-Saxon-Strutinsky method (the microscopic-macroscopic method)
combined with Kruppa's prescription for positive energy levels, which is
necessary to treat neutron rich nuclei, is studied to clarify the reason for
its success and to propose improvements for its shortcomings. The reason why
the plateau condition is met for the Nilsson model but not for the Woods-Saxon
model is understood in a new interpretation of the Strutinsky smoothing
procedure as a low-pass filter. Essential features of Kruppa's level density is
extracted in terms of the Thomas-Fermi approximation modified to describe
spectra obtained from diagonalization in truncated oscillator bases. A method
is proposed which weakens the dependence on the smoothing width by applying the
Strutinsky smoothing only to the deviations from a reference level density. The
BCS equations are modified for the Kruppa's spectrum, which is necessary to
treat the pairing correlation properly in the presence of continuum. The
potential depth is adjusted for the consistency between the microscopic and
macroscopic Fermi energies. It is shown, with these improvements, that the
microscopic-macroscopic method is now capable to reliably calculate binding
energies of nuclei far from stability.Comment: 66 pages, 29 figures, 1 tabl
Further explorations of Skyrme-Hartree-Fock-Bogoliubov mass formulas. II: Role of the effective mass
We have constructed four new complete mass tables, referred to as HFB-4 to
HFB-7, each one including all the 9200 nuclei lying between the two drip lines
over the range of Z and N>8 and Z<120. HFB-4 and HFB-5 have the isoscalar
effective mass M*_s$ constrained to the value 0.92 M, with the former having a
density-independent pairing, and the latter a density-dependent pairing. HFB-6
and HFB-7 are similar, except that M*_s is constrained to 0.8 M. The rms errors
of the mass-data fits are 0.680, 0.675, 0.686, and 0.676 MeV, respectively,
almost as good as for the HFB-2 mass formula, for which M*_s was unconstrained.
However, as usual, the single-particle spectra depend significantly on M*_s.
This decoupling of the mass fits from the fits to the single-particle spectra
has been achieved only by making the cutoff parameter of the delta-function
pairing force a free parameter. An improved treatment of the center-of-mass
correction was adopted, but although this makes a difference to individual
nuclei it does not reduce the overall rms error of the fit. The extrapolations
of all four new mass formulas out to the drip lines are essentially the same as
for the original HFB-2 mass formula.Comment: 12 pages revtex, 9 eps figures, accepted for publication in Phys.
Rev.
Nuclear Ground-State Masses and Deformations
We tabulate the atomic mass excesses and nuclear ground-state deformations of
8979 nuclei ranging from O to . The calculations are based on the
finite-range droplet macroscopic model and the folded-Yukawa single-particle
microscopic model. Relative to our 1981 mass table the current results are
obtained with an improved macroscopic model, an improved pairing model with a
new form for the effective-interaction pairing gap, and minimization of the
ground-state energy with respect to additional shape degrees of freedom. The
values of only 9 constants are determined directly from a least-squares
adjustment to the ground-state masses of 1654 nuclei ranging from O to
106 and to 28 fission-barrier heights. The error of the mass model is
0.669~MeV for the entire region of nuclei considered, but is only 0.448~MeV for
the region above .Comment: 50 pages plus 20 PostScript figures and 160-page table obtainable by
anonymous ftp from t2.lanl.gov in directory masses, LA-UR-93-308
Assimilating SAR-derived water level data into a hydraulic model: a case study
Satellite-based active microwave sensors not only provide synoptic overviews of flooded areas, but also offer an effective way to estimate spatially distributed river water levels. If rapidly produced and processed, these data can be used for updating hydraulic models in near real-time. The usefulness of such approaches with real event data sets provided by currently existing sensors has yet to be demonstrated. In this case study, a Particle Filter-based assimilation scheme is used to integrate ERS-2 SAR and ENVISAT ASAR-derived water level data into a one-dimensional (1-D) hydraulic model of the Alzette River. Two variants of the Particle Filter assimilation scheme are proposed with a global and local particle weighting procedure. The first option finds the best water stage line across all cross sections, while the second option finds the best solution at individual cross sections. The variant that is to be preferred depends on the level of confidence that is attributed to the observations or to the model. The results show that the Particle Filter-based assimilation of remote sensing-derived water elevation data provides a significant reduction in the uncertainty at the analysis step. Moreover, it is shown that the periodical updating of hydraulic models through the proposed assimilation scheme leads to an improvement of model predictions over several time steps. However, the performance of the assimilation depends on the skill of the hydraulic model and the quality of the observation data
SoftKiller, a particle-level pileup removal method
Existing widely-used pileup removal approaches correct the momenta of
individual jets. In this article we introduce an event-level, particle-based
pileup correction procedure, SoftKiller. It removes the softest particles in an
event, up to a transverse momentum threshold that is determined dynamically on
an event-by-event basis. In simulations, this simple procedure appears to be
reasonably robust and brings superior jet resolution performance compared to
existing jet-based approaches. It is also nearly two orders of magnitude faster
than methods based on jet areas.Comment: 26 pages, 16 figures (2 appendices with further checks added
LDA+Gutzwiller Method for Correlated Electron Systems: Formalism and Its Applications
We introduce in detail our newly developed \textit{ab initio} LDA+Gutzwiller
method, in which the Gutzwiller variational approach is naturally incorporated
with the density functional theory (DFT) through the "Gutzwiller density
functional theory (GDFT)" (which is a generalization of original Kohn-Sham
formalism). This method can be used for ground state determination of electron
systems ranging from weakly correlated metal to strongly correlated insulators
with long-range ordering. We will show that its quality for ground state is as
high as that by dynamic mean field theory (DMFT), and yet it is computationally
much cheaper. In additions, the method is fully variational, the charge-density
self-consistency can be naturally achieved, and the quantities, such as total
energy, linear response, can be accurately obtained similar to LDA-type
calculations. Applications on several typical systems are presented, and the
characteristic aspects of this new method are clarified. The obtained results
using LDA+Gutzwiller are in better agreement with existing experiments,
suggesting significant improvements over LDA or LDA+U.Comment: 20 pages, 11 figure
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