Comparison of impact and radioactivity techniques and the magnetic dipole moments of the first 2 states in Os,Os, and Os

Comparison of IMPACT, PAC and Mössbauer effect measurements indicate that for g-factor measurements of Os nuclei Ni is a suitable ferromagnetic host whereas the use of Fe in IMPACT measurements may give erroneous results.     

A Testable Theory for the Emergence of the Classical World

The transition from the quantum to the classical world is not yet understood. Here, we take a new approach. Central to this is the understanding that measurement and actualization cannot occur except on some specific basis. However, we have no established theory for the emergence of a specific basis. Our framework entails the following: (i) Sets of N entangled quantum variables can mutually actualize one another. (ii) Such actualization must occur in only one of the 2^N possible bases. (iii) Mutual actualization progressively breaks symmetry among the 2^N bases. (iv) An emerging “amplitude” for any basis can be amplified by further measurements in that basis, and it can decay between measurements. (v) The emergence of any basis is driven by mutual measurements among the N variables and decoherence with the environment. Quantum Zeno interactions among the N variables mediates the mutual measurements. (vi) As the number of variables, N, increases, the number of Quantum Zeno mediated measurements among the N variables increases. We note that decoherence alone does not yield a specific basis. (vii) Quantum ordered, quantum critical, and quantum chaotic peptides that decohere at nanosecond versus femtosecond time scales can be used as test objects. (viii) By varying the number of amino acids, N, and the use of quantum ordered, critical, or chaotic peptides, the ratio of decoherence to Quantum Zeno effects can be tuned. This enables new means to probe the emergence of one among a set of initially entangled bases via weak measurements after preparing the system in a mixed basis condition. (ix) Use of the three stable isotopes of carbon, oxygen, and nitrogen and the five stable isotopes of sulfur allows any ten atoms in the test protein to be discriminably labeled and the basis of emergence for those labeled atoms can be detected by weak measurements. We present an initial mathematical framework for this theory, and we propose experiments.     

Pressure broadening of OCS in the 10μm region

We report diode laser heterodyne measurements of pressure-broadening coefficients of OCS in the 020°–00°0 vibrational band of OCS and compare these measurements and previously reported microwave measurements with calculations performed with a recent cutoff-free impact technique.     

Laser wavelength measurements and the speed of light

Early determinations of the speed of light, based on astronomical observations or terrestrial time-of-flight experiments, were largely superseded in the 1940's by measurements of the frequency and wavelength of microwave radiation. The results were limited by the uncertainty in the wavelength measurements, and it was apparent that greater accuracy could be achieved by using radiation of shorter wavelength. It was, however, not until the development of lasers, and the nonlinear optical techniques made possible by their high output intensities, that frequency measurements could be extended towards the visible region of the spectrum.Stimulated by a demand for a more precise knowledge of the speed of light for application in space research, geodesy, and metrology, a new series of determinations has recently taken place. The measurements were made upon the radiations from a number of different stabilized-laser systems operating in the near infrared and visible spectral regions. Several different interferometric techniques were developed for the wavelength measurements. The results have led to a new recommended value for the speed of light, 299 792 458±1.2 m s^–1, and to the possibility of re-defining the unit of length.     

Measurements of the production, decay and properties of the top quark: a review

With the full Tevatron Run II and early LHC data samples, the opportunity for furthering our understanding of the properties of the top quark has never been more promising. Although the current knowledge of the top quark comes largely from Tevatron measurements, the experiments at the LHC are poised to probe top-quark production and decay in unprecedented regimes. Although no current top quark measurements conclusively contradict predictions from the standard model, the precision of most measurements remains statistically limited. Additionally, some measurements, most notably A _FB in top quark pair production, show tantalizing hints of beyond-the-Standard-Model dynamics. The top quark sample is growing rapidly at the LHC, with initial results now public. This review examines the current status of top quark measurements in the particular light of searching for evidence of new physics, either through direct searches for beyond the standard model phenomena or indirectly via precise measurements of standard model top quark properties.     

Entanglement and the process of measuring the position of a quantum particle

We explore the entanglement-related features exhibited by the dynamics of a composite quantum system consisting of a particle and an apparatus (here referred to as the “pointer”) that measures the position of the particle. We consider measurements of finite duration, and also the limit case of instantaneous measurements. We investigate the time evolution of the quantum entanglement between the particle and the pointer, with special emphasis on the final entanglement associated with the limit case of an impulsive interaction. We consider entanglement indicators based on the expectation values of an appropriate family of observables, and also an entanglement measure computed on particular exact analytical solutions of the particle–pointer Schrödinger equation. The general behavior exhibited by the entanglement indicators is consistent with that shown by the entanglement measure evaluated on particular analytical solutions of the Schrödinger equation. In the limit of instantaneous measurements the system’s entanglement dynamics corresponds to that of an ideal quantum measurement process. On the contrary, we show that the entanglement evolution corresponding to measurements of finite duration departs in important ways from the behavior associated with ideal measurements. In particular, highly localized initial states of the particle lead to highly entangled final states of the particle–pointer system. This indicates that the above mentioned initial states, in spite of having an arbitrarily small position uncertainty, are not left unchanged by a finite-duration position measurement process.     

Overview of the current spectroscopy effort on the Livermore electron beam ion traps

An overview is given of the current spectroscopic effort on the Livermore electron beam ion trap facilities. The effort focuses on four aspects: spectral line position, line intensity, temporal evolution, and line shape. Examples of line position measurements include studies of the K-shell transitions in heliumlike Kr³⁴⁺ and the 2s-2p intrashell transitions in lithiumlike Th⁸⁷⁺ and U⁸⁹⁺, which provide benchmark values for testing the theory of relativistic and quantum electrodynamical contributions in high-Z ions. Examples of line intensity measurements are provided by measurements of the electron-impact excitation and dielectronic recombination cross sections of the heliumlike transition-metal ions Ti²⁰⁺ through Co²⁵⁺. A discussion of radiative lifetime measurements of metastable levels in heliumlike ions is given to illustrate our time-resolved spectroscopy techniques in the microsecond range. We also present a measurement of the spectral lineshape that illustrates the very low ion temperatures that can be achieved in an EBIT.     

Experiment planning: Optimal measurement by the minimal sample dispersion criterion

The criteria of optimum measurements based on a minimum dispersion and the variational problem of optimum distribution of measurements are formulated. An analytical solution for the density of measurement distribution in the case of optimum measurement is obtained and the discrete equivalent of the optimal measurement is constructed. Measurements with optimal distribution have the most stable characteristics. They provide the minimum loss of accuracy when the numbers of measurements are both changed and redistributed. An optimal measurement of any portion of measurements (reading of any detector) has the same contribution to the determination of the accuracy of measurements, i.e., optimal measurements provide equivalence (homogeneity) of the measurements at different points. Optimal measurements provide the best measure of not only the values of the function, but also of the values of an arbitrary parameter of this function. In this case, the best of the quadratic forms to determine an arbitrary parameter of measured function is the expression for the distribution function χ². Continuous representation of discretely defined distribution function χ², corresponding exactly to optimal distribution of the measurements is proposed. An example of solving the problem of planning the experiment is given: measuring the spatial parameters of the laser beam with the lowest standard deviation of a limited number of photodetectors.     

Measurements of the 10B (n,He) reaction rate in zppr

Direct measurements of the ¹⁰B(n, He) reaction rate have been made in ZPPR. The measurements were made by isotope-dilution mass spectrometric analysis of stainless-steel encapsulated samples of enriched ¹⁰B. The results demonstrate that direct measurements of the ¹⁰B reaction rate in ZPPR are obtainable to an accuracy of ～1%. Comparisons with calculations give a predicted-to-experiment value of ～0.93. This value is consistent with earlier Rockwell measurements in benchmark neutron fields and further supports a need for revision in the ENDF/B cross section for ¹⁰B above ～0.1 MeV.     

An experimental determination of the cross section of the swings band system of C3

The spectral absorption cross section of the Swings band of C₃ was determined from measurements behind incident shock waves that heated a gas mixture of argon and acetylene. These measurements spanned the spectral region between 300 and 540 nm, and were obtained at temperatures between 3200 and 4000°K. An electronic oscillator strength of 0.033 was deduced from the measurements.     

A mass spectrometric line for tritium analysis of water and noble gas measurements from different water amounts in the range of microlitres and millilitres

This paper describes the procedure followed for noble gas measurements for litres, millilitres and microlitres of water samples in our laboratory, including sample preparation, mass spectrometric measurement procedure, and the complete calibrations. The preparation line extracts dissolved gases from water samples of volumes of 0.2 μ l to 3 l and it separates them as noble and other chemically active gases. Our compact system handles the following measurements: (i) determination of tritium concentration of environmental water samples by the ³He ingrowth method; (ii) noble gas measurements from surface water and groundwater; and (iii) noble gas measurements from fluid inclusions of solid geological archives (e.g. speleothems). As a result, the tritium measurements have a detection limit of 0.012 TU, and the expectation value (between 1 and 20 TU) is within 0.2 % of the real concentrations with a standard deviation of 2.4 %. The reproducibility of noble gas measurements for water samples of 20–40 ml allows us to determine solubility temperatures by an uncertainty better than 0.5 °C. Moreover, noble gas measurements for tiny water amounts (in the microlitre range) show that the results of the performed calibration measurements for most noble gas isotopes occur with a deviation of less than 2 %. Theoretically, these precisions for noble gas concentrations obtained from measurements of waters samples of a few microlitres allow us to determine noble gas temperatures by an uncertainty of less than 1 °C. Here, we present the first noble gas measurements of tiny amounts of artificial water samples prepared under laboratory conditions.     

Picosecond ground state recovery of the F-center in RbCl,KCl and KBr

Abstract

Optical pump-probe measurements on the F-center in RbCl, KCl and KBr show a ps ground state recovery, when a substantial number of F-aggregates is present. The observed de-excitation process becomes faster for a larger concentration of aggregate centers and is related to energy transfer from the excited state of the F-center to aggregate centers. This energy transfer occurs towards F₂- and N-centers in KCl. Our results are in accordance with measurements of the quantum efficiency of the F-center luminescence and with transient absorption measurements.     

Observation of a strong inverse temperature dependence for the opacity of atmospheric water vapor in the MM continuum near 280 GHz

Using atmospheric opacity measurements made at 278 GHz (9.3 cm^–1) at McMurdo Station, Antarctica during the austral springs of 1986 and 1987, combined with measurements of water vapor profile and total column density from near-simultaneous balloon flights, we have determined the attenuation per mm of precipitable water vapor (pwv) at this frequency. Our data were taken at significantly lower temperatures than other measurements in the literature for which accompanying water vapor pressure and temperature data are available. The results show a strong inverse dependence with temperature: measured opacity per mm of pwv is roughly a factor of two times greater at –35°C than at –10°C and three times greater than measurements at the same wavelength at +25°C reported by Zammit and Ade. We briefly review various theories proposed to explain excess absorption in continuum regions. Our lowtemperature measurements demonstrate a significantly greater inverse temperature dependence than embodied in several formulations, theoretical or empirical, proposed to represent mm-wave attenuation as a function of temperature and water vapor. The present results are qualitatively similar to observations of strong inverse temperature dependence in the near IR, but if attributed to water vapor dimer formation, imply a greater binding energy for the dimer than generally proposed by others. There is some independent evidence for a local anomaly in temperature dependence as a function of frequency near 280 GHz. It remains to be established whether our own results are strongly frequency dependent or apply generally to the mm-wave continuum.     

Optical properties of excitons bound to neutral SiGa-donors in GaP and the degeneracy of the SiGa-donor ground state

Low temperature near band-edge absorption and luminescence spectra of Si-doped n-type GaP are reported. Electrical and optical evidence is presented that these spectra are due to the creation and decay of excitons bound to neutral Si donors on Ga sites. Several zero-phonon transitions, each with strong replications by momentum conserving phonons, were observed in both absorption and luminescence. From these measurements it is concluded that the ground state of the Si_Ga donor is split into two sublevels 0.6 meV apart. Crystals containing a sufficiently low concentration of S to be suitable for a reliable analysis of temperature-dependent Hall-effect measurements were selected by combining 300°K Hall-effect data with low temperature S-exciton absorption data. The electrical measurements support the identification of Si as the main shallow donor. Moreover, it is concluded from these measurements that the degeneracy of the ground state of a Ga-site donor is 3 times that of a P-site donor, in agreement with theoretical expectations.     

Revised ultraviolet absorption cross sections of H2CO for the HITRAN database

A revised set of temperature-dependent absorption cross sections for ultraviolet (UV) measurements of formaldehyde (H₂CO) has been derived from two existing sets of laboratory cross sections, one using a Fourier transform spectrometer (FTS), and one using a grating instrument. This is conducted to satisfy the recommendation of the HITRAN Advisory Committee to provide a dataset with the spectral resolution and wavelength calibration of Fourier transform spectrometer measurements with the better intensity calibration that the grating measurements obtained. The re-scaled cross sections are now in the HITRAN database, and are recommended for use in atmospheric measurements and modeling, including photolysis calculations.     

On the difference in the rise times of the two SES electric field components

The study of low frequency signal transmission in conductive media, reveals that the electric and magnetic fields follow diffusion type equations. In a previous paper (Varotsos et al.1)) experimental evidence was forwarded that for epicentral distances of the order of 100 km, the SES electric field variations precede those of the magnetic ones by a time of the order of 1 sec. In the present paper, we present evidence that this peculiarity still pertains (but to a smaller extent), when studying the differences in the components of the electric field. This cannot be probably observed in the scale of laboratory measurements, lying usually within the error bars of the current experimental facilities. A tentative theoretical justification, termed as τ-approximation, is presented which accounts for the measurements of electric field components. The present findings can provide a unique tool for the discrimination between remote and nearby sources by using data from electric measurements alone.     

Path integrals, the ABL rule and the three-box paradox

The three-box problem is analysed in terms of virtual pathways, interference between which is destroyed by a number of intermediate measurements. The Aharonov-Bergmann-Lebowitz (ABL) rule is shown to be a particular case of Feynman's recipe for assigning probabilities to exclusive alternatives. The ‘paradoxical’ features of the three box case arise in an attempt to attribute, in contradiction to the uncertainty principle, properties pertaining to different ensembles produced by different intermediate measurements to the same particle. The effect can be mimicked by a classical system, provided an observation is made to perturb the system in a non-local manner.     

Measurement of the Ratio of the Vibrational Raman Cross Section for H2O Vapor to the Nitrogen Vibrational-Rotational Raman Band

In this letter, measurements of the ratio of the v¹ Raman cross section for H²O vapor to the Nitrogen vibrational-rotational Raman band cross section are reported. These measurements, Involving as they do, the technique of laser atmospheric probing have cone about through methods not usually a part of the repertoire of the spectroscopist.     

Inverse method for determining the depth of nonhomogeneous surface layers in elastic solids from the measurements of the dispersion curves of group velocity of surface SH Waves

In this paper, the variational inverse method for determining the depth of nonhomogeneous surface layers in elastic materials, from the measurements of the group velocity of surface shear horizontal (SH) waves, is developed. The direct problem for a given a priori type of profile of the coefficientc44in(x) (e.g. linear, Gaussian, etc.) is solved. The dispersion curves of phase and group velocity of surface SH waves in nonhomogeneous solids are calculated. Experimental verification of the inverse method has been performed for step profiles (structure of Cu on steel). It is stated that the inverse method based on the measurements of group velocity (for step profile) gives a smaller error in the unknown depth of the surface layer than that resulting from the inverse method based on the measurements of phase velocity of surface SH waves.     

Electrostatic waves in a drifting ionospheric simulation plasma in the vicinity of the plasma frequency

Plasma drift effects on forced electrostatic oscillations are studied experimentally near the plasma frequency in a maxwellian plasma. Propagation measurements show an asymmetrical dispersion diagram; the drift velocity is also measured by a diagnostic method which can be applied to space measurements.