Probing two-level systems with electron spin inversion recovery of defects at the Si/SiO2_2 interface

The main feature of amorphous materials is the presence of excess vibrational modes at low energies, giving rise to the so called "boson peak" in neutron and optical spectroscopy. These same modes manifest themselves as two level systems (TLSs) causing noise and decoherence in qubits and other sensitive devices. Here we present an experiment that uses the spin relaxation of dangling bonds at the Si/(amorphous)SiO$_2$ interface as a probe of TLSs. We introduce a model that is able to explain the observed non-exponential electron spin inversion recovery and provides a measure of the degree of spatial localization and concentration of the TLSs close to the interface, their maximum energy and its temperature dependence.Comment: 4 pages, 2 figures, regular pape

Free Minimization of the Fundamental Measure Theory Functional: Freezing of Parallel Hard Squares and Cubes

Due to remarkable advances in colloid synthesis techniques, systems of squares and cubes, once an academic abstraction for theorists and simulators, are nowadays an experimental reality. By means of a free minimization of the free-energy functional, we apply Fundamental Measure Theory to analyze the phase behavior of parallel hard squares and hard cubes. We compare our results with those obtained by the traditional approach based on the Gaussian parameterization, finding small deviations and good overall agreement between the two methods. For hard squares our predictions feature at intermediate packing fraction a smectic phase, which is however expected to be unstable due to thermal fluctuations. This implies that for hard squares the theory predicts either a vacancy-rich second-order transition or a vacancy-poor weakly first-order phase transition at higher density. In accordance with previous studies, a second-order transition with a high vacancy concentration is predicted for hard cubes

Density Functional Theory for Chiral Nematic Liquid Crystals

Even though chiral nematic phases were the first liquid crystals experimentally observed more than a century ago, the origin of the thermodynamic stability of cholesteric states is still unclear. In this Letter we address the problem by means of a novel density functional theory for the equilibrium pitch of chiral particles. When applied to right-handed hard helices, our theory predicts an entropy-driven cholesteric phase, which can be either right- or left-handed, depending not only on the particle shape but also on the thermodynamic state. We explain the origin of the chiral ordering as an interplay between local nematic alignment and excluded-volume differences between left- and right-handed particle pairs

Pulse-Shape Discrimination of CaF2(Eu)

We measured the decay time of the scintillation pulses produced by electron and nuclear recoils in CaF2(Eu) by a new fitting method. In the recoil energy region 5-30 keVee, we found differences of the decay time between electron and nuclear recoil events. In the recoil energy region above 20 keVee, we found that the decay time is independent of the recoil energy.Comment: 10 pages, 4 figure

Many time scales in a single GRB

In some Gamma-Ray Bursts (GRBs) it has been possible to identify different time scales of variability. Certainly such a behaviour can easily be revealed in strong events, but it might represent a general behaviour of the GRBs. In this paper we report results of temporal variability for 5 events, 2 recorded by the previous experiments SIGNE and KONUS and 3 by the experiment BATSE on board the CGRO satellite. This kind of analysis up to date can give new information to understand the origin of GRBs and the relative scenario of the burst energy emission

Quinney: The Social Reality of Crime

A Review of The Social Reality of Crime by Richard Quinne

Tort Trends in 1957

This articles discusses trends in tort cases in 1957, including adequate awards, avaition law, jury fixing, the need for medico-legal training, insurance limits, consortium, charitable immunity, assumption of risk, res ipsa loquitur, workmen\u27s compensation, injuries in utero, warranties, interfamilial suits, expert witnesses, dead men\u27s statutes, and personal injury law reform