Pulse processing routines for neutron time-of-flight data

A pulse shape analysis framework is described, which was developed for n_TOF-Phase3, the third phase in the operation of the n_TOF facility at CERN. The most notable feature of this new framework is the adoption of generic pulse shape analysis routines, characterized by a minimal number of explicit assumptions about the nature of pulses. The aim of these routines is to be applicable to a wide variety of detectors, thus facilitating the introduction of the new detectors or types of detectors into the analysis framework. The operational details of the routines are suited to the specific requirements of particular detectors by adjusting the set of external input parameters. Pulse recognition, baseline calculation and the pulse shape fitting procedure are described. Special emphasis is put on their computational efficiency, since the most basic implementations of these conceptually simple methods are often computationally inefficient.Comment: 13 pages, 10 figures, 5 table

Long-Lived Time-Dependent Remnants During Cosmological Symmetry Breaking: From Inflation to the Electroweak Scale

Through a detailed numerical investigation in three spatial dimensions, we demonstrate that long-lived time-dependent field configurations emerge dynamically during symmetry breaking in an expanding de Sitter spacetime. We investigate two situations: a single scalar field with a double-well potential and the bosonic sector of an SU(2) non-Abelian Higgs model. For the single scalar, we show that large-amplitude oscillon configurations emerge spontaneously and persist to contribute about 1.2% of the energy density of the universe. We also show that for a range of parameters, oscillon lifetimes are enhanced by the expansion and that this effect is a result of parametric resonance. For the SU(2) case, we see about 4% of the final energy density in oscillons.Comment: 10 pages, RevTex4, 6 figures; v2: expanded SU(2) model section, added 2 figures, added one section, improved overall presentation and updated references, accepted for publication in Phys. Rev. D. Results remain the sam

Emergence of Oscillons in an Expanding Background

We consider a (1+1) dimensional scalar field theory that supports oscillons, which are localized, oscillatory, stable solutions to nonlinear equations of motion. We study this theory in an expanding background and show that oscillons now lose energy, but at a rate that is exponentially small when the expansion rate is slow. We also show numerically that a universe that starts with (almost) thermal initial conditions will cool to a final state where a significant fraction of the energy of the universe -- on the order of 50% -- is stored in oscillons. If this phenomenon persists in realistic models, oscillons may have cosmological consequences.Comment: 13 pages, 4 .eps figures, uses RevTeX4; v2: clarified details of expansion, added reference

Information Content of Spontaneous Symmetry Breaking

We propose a measure of order in the context of nonequilibrium field theory and argue that this measure, which we call relative configurational entropy (RCE), may be used to quantify the emergence of coherent low-entropy configurations, such as time-dependent or time-independent topological and nontopological spatially-extended structures. As an illustration, we investigate the nonequilibrium dynamics of spontaneous symmetry-breaking in three spatial dimensions. In particular, we focus on a model where a real scalar field, prepared initially in a symmetric thermal state, is quenched to a broken-symmetric state. For a certain range of initial temperatures, spatially-localized, long-lived structures known as oscillons emerge in synchrony and remain until the field reaches equilibrium again. We show that the RCE correlates with the number-density of oscillons, thus offering a quantitative measure of the emergence of nonperturbative spatiotemporal patterns that can be generalized to a variety of physical systems.Comment: LaTeX, 9 pages, 5 figures, 1 tabl

Case Histories of Damage of Foundations Near Sliding Slopes

The paper studies the effect of large slope movements on foundations through case histories. More than 30 well-documented case histories of damaged buildings near the tip of slopes due to excessive movement caused by either heavy rain or earthquakes were collected. The case histories showed that a critical factor affecting the level of damage of buildings, is the coefficient Ι, that is defined as the ratio of the width below the foundation that settles by the total width of the foundation: (a) When Ι \u3c 0.2, collapse does not occur, even if settlement is very large, (b). When 0.2 \u3c Ι \u3c 1.0, the level of damage depends both on settlement and the factor l. (c) When Ι=1, buildings may not collapse, even if the settlement is very large, about 1m, but damage and rotation may be high. The above hold regardless of the cause of the slide: heavy rain or earthquake

Lateral Stress Ratio on Retaining Structures after Earthquake loading

Equations are derived by analysis g1vmg the earthquake-induced change in the permanent horizontal stress acting on frictionless vertical walls retaining dry sand. These equations exhibit a limit in the coefficient of lateral pressure that depends only on the slope of the critical state line and the Poisson\u27s Ratio of the backfill. The horizontal stress after dynamic shaking increases or decreases towards this limit. Predictions agree qualitatively with results of laboratory tests

Constitutive Models Predicting the Response of Clays Along Slip Surfaces

The paper proposes and validates a constitutive model simulating the change of resistance along clay slip surfaces under both undrained and drained conditions. The proposed model is based on (a) the critical state theory and (b) the assumption that the critical state changes once failure is reached, in terms of the further shear displacement. Under undrained conditions, the proposed model simulates the excess pore pressure generation and subsequently the continuous change of clay resistance along the slip surface from its initial value to the peak strength and then at large displacement the residual value measured in constant-volume ring shear tests. Under drained conditions, the model simulates the normal displacement change and subsequently the change of clay resistance along the slip surface in clays as measured in drained ring shear tests

Geotechnical Factors in Recent Earthquake-Induced Structural Failures in Greece

A review is made of geotechnical factors that played an important role in three recent earthquake-induced failures, two of which were deadly. The first two catastrophes concern two five-storey hotels that collapsed during the “Alkyonides earthquake” of 24 February 1981 (M=6.7) and the “Egion earthquake” of 15 June 1995 (M=6.2). The third failure is the collapse of a multi-storey factory caused by the “Athens earthquake” of 7 September 1999 (M=5.9). In the first two catastrophes, ground subsidence was estimated by two different methods and was found to be of the order of 0.13 to 0.46 m. These estimates are based on tentative assumptions that should be reviewed and possibly revised. Considerable differential settlements must have existed before the earthquake, as there were no basements that would have attenuated vertical loading and so even a moderate additional differential settlement could cause failure. In the third case, the structure was built near the edge of a steep slope of clayey soil. The co-seismic shear displacement caused the footings resting on the sliding mass to settle, thus causing severe distortions to the structure

Measurement of the240Pu(n,f) cross-section at the CERN n-TOF facility: First results from EAR-2

The accurate knowledge of neutron cross-sections of a variety of plutonium isotopes and other minor actinides, such as neptunium, americium and curium, is crucial for feasibility and performance studies of advanced nuclear systems (Generation-IV reactors, Accelerator Driven Systems). In this context, the240Pu(n,f) cross-section was measured with the time-of-flight technique at the CERN n-TOF facility at incident neutron energies ranging from thermal to several MeV. The present measurement is the first to have been performed at n-TOF's newly commissioned Experimental Area II (EAR-2), which is located at the end of an 18 m neutron beam-line and features a neutron fluence that is 25-30 times higher with respect to the existing 185 m flight-path (EAR-1), as well as stronger suppression of sample-induced backgrounds, due to the shorter times-of-flight involved. Preliminary results are presented. © 2015, CERN. All rights reserved.Postprint (published version