126 research outputs found
Structure And Properties Of Silver Borate Glasses
Clear glasses form in the system Ag2OâB2O3 up to about 35 mol% (65 wt%) Ag2O. Infrared absorption, thermal expansion, and density data indicated an analogy to the Na2OâB2O3 system. Pentaborateâtriborate group pairs appear to be formed on addition of Ag2O to B2O3 up to 20 mol% Ag2O and diborate groups from 20 to 33 mol% Ag2O. This interpretation is supported by the comparison of the infrared absorption spectra of quenched and crystallized glasses. One crystallization product, Ag2Oâ4B2O3, was identified previously. A new compound starts to appear at 28 mol% Ag2O. The theory that silver is generally present as a network modifier like sodium was substantiated by the comparison of the molar volume of sodium and silver borate glasses. Above 27 mol% Ag2O some atomic silver is assumed to be present; below 15 mol%, exploratory studies indicate a twoâphase structure within an immiscibility gap. A lowâtemperature internal friction peak in the glasses up to 28 mol% Ag2O corresponds to the alkali peak in other glasses; a high temperature peak appearing in the 34 mol% Ag2O glass is associated with the appearance of nonbridging oxygen in the system. Copyright © 1971, Wiley Blackwell. All rights reserve
A new approach to quantum backflow
We derive some rigorous results concerning the backflow operator introduced
by Bracken and Melloy. We show that it is linear bounded, self adjoint, and not
compact. Thus the question is underlined whether the backflow constant is an
eigenvalue of the backflow operator. From the position representation of the
backflow operator we obtain a more efficient method to determine the backflow
constant. Finally, detailed position probability flow properties of a numerical
approximation to the (perhaps improper) wave function of maximal backflow are
displayed.Comment: 12 pages, 8 figure
Polynary Silicon Arsenic Chalcogenide Glasses With High Softening Temperatures
The introduction of Ag in SiAsTe glasses permits the incorporation of Se, otherwise volatile and/or degradable as a constituent in Si-containing chalcogenide glasses. SiAsAgTeSe glasses exhibit much higher softening ranges and glass transition temperatures than encountered in known chalgogenide systems. A glass Si35As15Ag10Te20Se20 had the viscosity log Μ = 13 at about 500°C, as compared to 370°C for the base glass Si35As25Te40, the viscosity of log Μ = 9.8 at about 560°C, as compared to 442°C for the base glass. Phase separation occurs in the system SiAsAgTeSe and becomes manifest in two glass transitions indicated by changes in the slopes of the expansion curves and breaks in the softening point-composition relations. The existence and behavior SiAsAgTeSe glasses suggests the possible development of higher Tg i.r. transparencies and higher Tg semiconductor glasses than described so far. © 1973
Bohmian arrival time without trajectories
The computation of detection probabilities and arrival time distributions
within Bohmian mechanics in general needs the explicit knowledge of a relevant
sample of trajectories. Here it is shown how for one-dimensional systems and
rigid inertial detectors these quantities can be computed without calculating
any trajectories. An expression in terms of the wave function and its spatial
derivative, both restricted to the boundary of the detector's spacetime volume,
is derived for the general case, where the probability current at the
detector's boundary may vary its sign.Comment: 20 pages, 12 figures; v2: reference added, extended introduction,
published versio
HV/HR-CMOS sensors for the ATLAS upgradeâconcepts and test chip results
In order to extend its discovery potential, the Large Hadron Collider (LHC) will have a major upgrade (Phase II Upgrade) scheduled for 2022. The LHC after the upgrade, called High-Luminosity LHC (HL-LHC), will operate at a nominal leveled instantaneous luminosity of 5Ă 1034 cmâ2 sâ1, more than twice the expected Phase I . The new Inner Tracker needs to cope with this extremely high luminosity. Therefore it requires higher granularity, reduced material budget and increased radiation hardness of all components. A new pixel detector based on High Voltage CMOS (HVCMOS) technology targeting the upgraded ATLAS pixel detector is under study. The main advantages of the HVCMOS technology are its potential for low material budget, use of possible cheaper interconnection technologies, reduced pixel size and lower cost with respect to traditional hybrid pixel detector. Several first prototypes were produced and characterized within ATLAS upgrade R&D effort, to explore the performance and radiation hardness of this technology.
In this paper, an overview of the HVCMOS sensor concepts is given. Laboratory tests and irradiation tests of two technologies, HVCMOS AMS and HVCMOS GF, are also given
Photometry of ET Andromedae and pulsation of HD 219891
ET And is a binary system with a B9p(Si) star as the main component. We report on the photometric observing campaigns in 1988, 1989 and 1994 which confirmed the rotation period of 1(.)(d)618875 for ET And while refuting other published values. Furthermore, the controversial issue of pulsational stability of ET And is resolved since we have discovered pulsation for HD 219891, which was the main comparison star and sometimes exclusively used. The frequency of 10.0816 d(-1), a semi-amplitude of 2.5 mmag, T(eff) and M(v) suggest this comparison star to be a delta Scuti variable close to the blue border of the instability strip. The pulsational stability of ET And could be clearly established and hence no need exists to derive new driving mechanisms for stars between the classical instability strip and the region of slowly pulsating B-type (SPB) stars
Radiation-hard active pixel sensors for HL-LHC detector upgrades based on HV-CMOS technology
Luminosity upgrades are discussed for the LHC (HL-LHC) which would make updates to the detectors necessary, requiring in particular new, even more radiation-hard and granular, sensors for the inner detector region.
A proposal for the next generation of inner detectors is based on HV-CMOS: a new family of silicon sensors based on commercial high-voltage CMOS technology, which enables the fabrication of part of the pixel electronics inside the silicon substrate itself.
The main advantages of this technology with respect to the standard silicon sensor technology are: low material budget, fast charge collection time, high radiation tolerance, low cost and operation at room temperature.
A traditional readout chip is still needed to receive and organize the data from the active sensor and to handle high-level functionality such as trigger management. HV-CMOS has been designed to be compatible with both pixel and strip readout.
In this paper an overview of HV2FEI4, a HV-CMOS prototype in 180 nm AMS technology, will be given. Preliminary results after neutron and X-ray irradiation are shown
The Detection of Multimodal Oscillations on Alpha UMa
We have used the star camera on the WIRE satellite to observe the K0 III star
Alpha UMa, and we report the apparent detection of 10 oscillation modes. The
lowest frequency mode is at 1.82 microhertz, and appears to be the fundamental
mode. The mean spacing between the mode frequencies is 2.94 microhertz, which
implies that all detected modes are radial. The mode frequencies are consistent
with the physical parameters of a K0 III star, if we assume that only radial
modes are excited. Mode amplitudes are 100 -- 400 micromagnitudes, which is
consistent with the scaling relation of Kjeldsen & Beddinge (1995).Comment: ApJ Letters, in press. 14 pages, including 3 figure
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