Photon storage with sub-nanosecond readout rise time in coupled quantum wells

Photon storage with 250 ps rise time of the readout optical signal was implemented with indirect excitons in coupled quantum well nanostructures (CQW). The storage and release of photons was controlled by the gate voltage pulse. The transient processes in the CQW were studied by measuring the kinetics of the exciton emission spectra after application of the gate voltage pulse. Strong oscillations of the exciton emission wavelength were observed in the transient regime when the gate voltage pulse was carried over an ordinary wire. Gating the CQW via an impedance-matched broadband transmission line has lead to an effective elimination of these transient oscillations and expedient switching of the exciton energy to a required value within a short time, much shorter than the exciton lifetime.Comment: 9 pages including 3 figures. The following article has been accepted by Journal of Applied Physics. After it is published, it will be found at http://jap.aip.org

Electrostatic Conveyer for Excitons

We report on the study of indirect excitons in moving lattices - conveyers created by a set of AC voltages applied to the electrodes on the sample surface. The wavelength of this moving lattice is set by the electrode periodicity, the amplitude is controlled by the applied voltage, and the velocity is controlled by the AC frequency. We observed the dynamical localization-delocalization transition for excitons in the conveyers and measured its dependence on the exciton density and conveyer amplitude and velocity. We considered a model for exciton transport via conveyers. The theoretical simulations are in agreement with the experimental data.Comment: 4 pages, 4 figures + supplemental material including two video

Nucleus-nucleus scattering in perturbative QCD with Nc→∞N_c\to\infty

In the perturbative QCD with $N_c\to\infty$ equations for the amplitude of the nucleus-nucleus scattering are derived by the effective field method. The asymptotic form of the solution is discussed. It is argued that in the high-energy limit the total nucleus-nucleus cross-sections become constant and purely geometrical.Comment: 11 pages in LaTe

Boundary conditions in the QCD nucleus-nucleus scattering problem

In the framework of the effective field theory for interacting BFKL pomerons, applied to nucleus-nucleus scattering, boundary conditions for the classical field equations are discussed. Correspondence with the QCD diagrams at the boundary rapidities requires pomeron interaction with the participating nuclei to be exponential and non-local. Commonly used 'eikonal' boundary conditions, local and linear in fields, follow in the limit of small QCD pomeron-nucleon coupling. Numerical solution of the classical field equations, which sum all tree diagrams for central gold-gold scattering, demonstrates that corrected boundary conditions lead to substantially different results, as compared to the eikonal conditions studied in earlier publications. A breakdown of projectile-target symmetry for particular solutions discovered earlier in \cite{bom} is found to occur at roughly twice lower rapidity. Most important, due to a high non-linearity of the problem, the found asymmetric solutions are not unique but form a family growing in number with rapidity. The minimal value for the action turns out to be much lower than with the eikonal boundary conditions and saturates at rapidities around 10.Comment: 19 pages, 8 figure

A Pomeron Approach to Hadron-Nucleus and Nucleus-Nucleus "Soft" Interactions at High Energy

We formulate a generalization of the Glauber formalism for hadron-nucleus and nucleus-nucleus collisions based on the Pomeron approach to high energy interactions. Our treatment is based on two physical assumptions (i.e. two small parameters) : (i) that only sufficiently small distances contribute to the Pomeron structure; and (ii) the triple Pomeron vertex $G_{3P}/g_{P-N} \ll 1$ (where $g_{P-N}$ is the Pomeron-nucleon vertex) is small. A systematic method is developed for calculating the total, elastic and diffractive dissociation cross sections as well as the survival probability of large rapidity gap processes and inclusive observables, both for hadron - nucleus and nucleus-nucleus collisions. Our approach suggests saturation of the density of the produced hadrons in nucleus-nucleus collisions, the value of the saturation density turns out to be large and depends on the number of nucleons in the lightest nucleus.Comment: 54 pages, 63 figure

Environmental assessment proposed license renewal of Nuclear Metals, Inc. Concord, Massachusetts

The US Nuclear Regulatory Commission (NRC) has prepared this Environmental Assessment (EA) to evaluate environmental issues associated with the renewal of licenses issued by NRC for facilities operated by Nuclear Metals, Inc. (NMI) in Concord, Massachusetts. By renewing the licenses, NRC proposes to allow the continuation of ongoing operations involving radioactive materials at NMI`s facilities. This EA focuses on the potential impacts related to air emissions at NMI during normal (incident-free) operations and accidental releases. Findings indicate that there are only two areas of potential concern. First, modeling results for sulfur dioxide (SO{sub 2}) emissions from the boilers during normal operations indicate that the potential exists for exceeding the short-term National Ambient Air Quality Standards (NAAQS). NMI is prepared to undertake mitigative action to prevent potential exceedances of the short-term SO{sub 2} NAAQS, and the Massachusetts Department of Environmental Protection is prepared to resolve the issue via a permit/approval change or through a Consent Order. Second, in the unlikely event of a severe fire, predicted sulfuric acid (H{sub 2}SO{sub 4}) concentrations based on conservative (upper bound) modeling exceed the Emergency Response Planning Guideline (ERPG) levels. NMI has committed to NRC to give a briefing for local emergency response officials regarding the potential for an accidental H{sub 2}SO{sub 4} release

The chemistry and properties of magnesia-phosphate cement systems

Includes bibliographical referencesAvailable from British Library Document Supply Centre- DSC:DX218773 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo