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1.
V. Zacek 《Il Nuovo Cimento C》1986,9(2):516-521
Summary The positron spectrum from the reaction
was measured at two distances 37.9 m and 45.9 m from the core of the 2.8 GW power reactor in G?sgen (Switzerland). The data
were analysed in terms of two neutrino oscillations of the disappearance type
. No evidence for neutrino oscillations was found and limits on the oscillation parameters Δm
2 and sin22θ were derived.
Riassunto Si è misurato lo spettro dei positroni della reazione alle due distanze di 37.9 m e 45.9 dal nucleo del reattore di potenza di G?sgen (Svizzera). Si sono analizzati i dati in termini di due oscillazioni del tipo della sparizione . Non si è trovata alcuna prova di oscillazioni del neutrino e si sono dedotti limiti ai parametri di oscillazione Δm 2 e sin22θ.
Резюме Измерялся спектр позитронов из реакции на двух расстояниях 37.9 м и 45.9 м от активной зоны энергетического реактора в Гэсгене (Щвейцария). Полученные данные анализируются на основе двух нейтринных осцилляций исчезающего типа . Не было обнаружено доказательств для нейтринных осцилляций. Определяются пределы для параметров осцилляций Δm 2 и sin22θ.相似文献
2.
3.
Full distributed fiber optical sensor for intrusion detection in application to buried pipelines 总被引:5,自引:0,他引:5
Based on the microbend effect of optical fiber, a distributed sensor for real-time continuous monitoring of intrusion in application to buried pipelines is proposed. The sensing element is a long cable with a special structure made up of an elastic polymer wire, an optical fiber, and a metal wire. The damage point is located with an embedded optical time domain reflectometry (OTDR) instrument. The intrusion types can be indicated by the amplitude of output voltage. Experimental results show that the detection system can alarm adequately under abnormal load and can locate the intrusion point within 22.4 m for distance of 3.023 km. 相似文献
4.
We study the dynamics of the thermal momentum distribution function for an interacting, homogeneous Fermi gas on ℤ3 in the presence of an external weak static random potential, where the pair interactions between the fermions are modeled
in dynamical Hartree-Fock theory. We determine the Boltzmann limits associated to different scaling regimes defined by the
size of the random potential, and the strength of the fermion interactions. 相似文献
5.
Laurent Desvillettes François Golse Valeria Ricci 《Journal of statistical physics》2008,131(5):941-967
We propose a mathematical derivation of Brinkman’s force for a cloud of particles immersed in an incompressible viscous fluid.
Specifically, we consider the Stokes or steady Navier-Stokes equations in a bounded domain Ω⊂ℝ3 for the velocity field u of an incompressible fluid with kinematic viscosity ν and density 1. Brinkman’s force consists of a source term 6π
ν
j where j is the current density of the particles, and of a friction term 6π
ν
ρ
u where ρ is the number density of particles. These additional terms in the motion equation for the fluid are obtained from the Stokes
or steady Navier-Stokes equations set in Ω minus the disjoint union of N balls of radius ε=1/N in the large N limit with no-slip boundary condition. The number density ρ and current density j are obtained from the limiting phase space empirical measure
, where x
k
is the center of the k-th ball and v
k
its instantaneous velocity. This can be seen as a generalization of Allaire’s result in [Arch. Ration. Mech. Anal. 113:209–259,
[1991]] who considered the case of periodically distributed x
k
s with v
k
=0, and our proof is based on slightly simpler though similar homogenization arguments. Similar equations are used for describing
the fluid phase in various models for sprays. 相似文献
6.
In multi-beam coherent combination laser systems, piston aberration between each sub-beam is often regarded as the dominative factor to deteriorate the combination performance. So as to obtain a favorable combination result, a Hartmann phase pick-up method in combination with a seven-element active segmented mirror is presented to pick up and correct the piston aberrations of a seven-beam coherent combination system. A simulative result indicates that the RMS value of the wavefront can be reduced from 401 nm to 3.7 nm, while the far-field Strehl ratio can be increased from 0.22 to 0.99 after correction. 相似文献
7.
M. Miyabe M. Oba H. Iimura K. Akaoka Y. Maruyama I. Wakaida 《Applied Physics A: Materials Science & Processing》2010,101(1):65-70
A cerium oxide sample was ablated by 2nd harmonic radiation of Nd:YAG laser at a power density of 0.1 GW/cm2. Time evolution of the ablation plume was investigated by laser absorption time-of-flight (TOF) measurement. It was found
that the ablated ionic plume in vacuum consisted of two components having different velocities whereas the ablated neutral
atoms had mainly a single component. The flow velocity perpendicular to the sample surface in vacuum was determined to be
3.5 km/s for neutral atoms, and 4.7 km/s and 9.3 km/s for singly charged ions. From the detailed plume evolution in ambient
atmosphere with several pressures we obtained some experimental conditions suitable for isotope analysis of atomic cerium. 相似文献
8.
We study the problem of localizing and tracking in a confocal laser scanning microscope a single fluorescent particle diffusing
in three dimensions. The position of the particle is estimated from a collection of intensity measurements using a novel analytical
algorithm. This estimator is then combined with a tracking algorithm based on a linear quadratic Gaussian controller to steer
the detection volume of the microscope and follow the molecule. The feasibility of the approach is demonstrated through numerical
simulations. These results indicate that, in such a system, tracking in three dimensions of a particle moving with a diffusion
constant larger than 1 μm2/s is possible without the need for additional sensors or lasers. 相似文献
9.
V. Dinca A. Palla-Papavlu M. Dinescu J. Shaw?Stewart T. K. Lippert F. Di Pietrantonio D. Cannata M. Benetti E. Verona 《Applied Physics A: Materials Science & Processing》2010,101(3):559-565
This paper presents polymer pixel printing for applications in chemoselective sensors where nanosecond laser direct transfer methods, with a triazene polymer (TP) acting as a Dynamic Release Layer (DRL), are used. A systematic study of laser fluence, donor film morphology and both single- and multiple-pixel deposition were optimized with the final goal to obtain continuous pixels of sensitive polymers, polyethylenimine (PEI) and polyisobutylene (PIB), on SAW surfaces. Morphology characterization after the laser transfer has been performed by Optical Microscopy and Scanning Electron Microscopy (SEM). The responses of the coated transducers were measured after deposition with different laser fluences and it was found that a fluence under 625 mJ/cm2 was required in order to prevent damage of the interdigital transducers (IDT) of the sensor devices. The sensitivity of the polymer coated devices to acetone concentrations gives an indication that LIFT can be used for printing sensitive polymer pixels onto transducer devices. 相似文献
10.
11.
Performance comparison of interferometer topologies for carrier-envelope phase detection 总被引:1,自引:0,他引:1
Performance and noise immunity of different interferometer set-ups for carrier-envelope phase detection are compared. The
frequently used Mach–Zehnder interferometer is found to be easily corrupted by acoustic noise contributions and air streaks,
whereas a quasi-common-path variant of the f-to-2f interferometer exhibits a 40% reduction of residual noise. This comparative analysis also provides deeper insight into additional
mechanisms that are currently limiting the performance of carrier-envelope phase stabilization schemes. 相似文献
12.
Mid-infrared laser absorption sensors based on quantum cascade laser (QCL) technology offer the potential for high-sensitivity, selective, and high-speed measurements of temperature and concentration for species of interest in high-temperature environments, such as those found in combustion devices. A new mid-infrared QCL absorption sensor for carbon monoxide and temperature measurements has been developed near the intensity peak of the CO fundamental band at 4.6 μm, providing orders-of-magnitude greater sensitivity than the overtone bands accessible with telecommunications lasers. The sensor is capable of probing the R(9), R(10), R(17), and R(18) transitions of the CO fundamental ro-vibrational band which are located at frequencies where H2O and CO2 spectral interference is minimal. Temperature measurements are made via scanned-wavelength two-line ratio techniques using either the R(9) and R(17) or the R(10) and R(18) line pairs. The high-speed (1–2 kHz) scanned-wavelength sensor is demonstrated in room-temperature gas cell measurements of CO and, to demonstrate the potential of the sensor for high-temperature thermometry, in shock-heated gases containing CO for a very wide range of temperature (950–3500 K) near 1 atm. To our knowledge, these measurements represent the first use of QCL-based absorption sensor for thermometry at elevated combustion-like temperatures. The high-temperature measurements of CO mole fraction and temperature agree with the post-reflected-shock conditions within ±1.5% and ±1.2% (1σ deviation), respectively. 相似文献
13.
Based on the configuration-space generating functional of the Green functions for the gauge-invariant system in higher-order
derivatives theories, the equations of the transformation properties at the quantum level have been derived. It follows that
the sufficient conditions are found which implies that there exists the conservation laws and the expressions of the quantal
conserved laws are also given. Applying the results to the non-Abelian Chern-Simons higher-order derivatives theories, the
quantal BRST conserved charge and other conserved charges are found, the transformation properties of the conformal transformation
at the quantum level is discussed, the quantal conserved angular momentum is derived, it is pointed out that fractional spin
in this system may be also preserved in quantum theories. But the connection between the symmetries and conservation laws
in classical theories are not always preserved in quantum theories. 相似文献
14.
A. N. Shmelev G. G. Kulikov V. A. Kurnaev G. H. Salahutdinov E. G. Kulikov V. A. Apse 《Physics of Atomic Nuclei》2015,78(10):1100-1111
Discussions are currently going on as to whether it is suitable to employ thorium in the nuclear fuel cycle. This work demonstrates that the 231Pa–232U–233U–Th composition to be produced in the thorium blanket of a hybrid thermonuclear reactor (HTR) as a fuel for light-water reactors opens up the possibility of achieving high, up to 30% of heavy metals (HM), or even ultrahigh fuel burnup. This is because the above fuel composition is able to stabilize its neutron-multiplying properties in the process of high fuel burnup. In addition, it allows the nuclear fuel cycle (NFC) to be better protected against unauthorized proliferation of fissile materials owing to an unprecedentedly large fraction of 232U (several percent!) in the uranium bred from the Th blanket, which will substantially hamper the use of fissile materials in a closed NFC for purposes other than power production. 相似文献
15.
Yuri P. Kalmykov William T. Coffey Serguey V. Titov 《Journal of statistical physics》2008,131(5):969-987
A master equation, for the time evolution of the quasi-probability density function of spin orientations in the phase space
representation of the polar and azimuthal angles is derived for a uniaxial spin system subject to a magnetic field parallel
to the axis of symmetry. This equation is obtained from the reduced density matrix evolution equation (assuming that the spin-bath
coupling is weak and that the correlation time of the bath is so short that the stochastic process resulting from it is Markovian)
by expressing it in terms of the inverse Wigner-Stratonovich transformation and evaluating the various commutators via the
properties of polarization operators and spherical harmonics. The properties of this phase space master equation, resembling
the Fokker-Planck equation, are investigated, leading to a finite series (in terms of the spherical harmonics) for its stationary
solution, which is the equilibrium quasi-probability density function of spin “orientations” corresponding to the canonical
density matrix and which may be expressed in closed form for a given spin number. Moreover, in the large spin limit, the master
equation transforms to the classical Fokker-Planck equation describing the magnetization dynamics of a uniaxial paramagnet. 相似文献
16.
Song Mao Ma Wen-Gan Zhang Ren-You Guo Lei Wang Shao-Ming 《The European Physical Journal C - Particles and Fields》2009,59(4):761-768
Higgs-boson production in association with a W-boson pair at e
+
e
− linear colliders is one of the important processes in probing the coupling between the Higgs boson and vector gauge bosons
and discovering the signature of new physics. We describe the impact of the complete electroweak (EW) radiative corrections
of
to this process in the standard model (SM) at the International Linear Collider (ILC), and investigate the dependence of the
lowest-order (LO) and EW next-to-leading order (NLO) corrected cross sections on the colliding energy
and the Higgs-boson mass. The LO and NLO EW corrected distributions of the invariant mass of the W-boson pair and the transverse
momenta of the final W-boson and Higgs boson are presented. Our numerical results show that the relative EW radiative correction
(δ
ew) varies from −19.4% to 0.2% when m
H=120 GeV and
grows from 300 GeV to 1.2 TeV. 相似文献
17.
An exact expression for the functional derivative of the distribution function of a -nucleon pair in nuclear matter is derived. An approximate expression is also derived by means of the Kirkwood superposition approximation. The latter expression is subsequently used to obtain the Euler equation for the correlation functionf(r1) of a -nucleon pair in nuclear matter. 相似文献
18.
Hilton RR 《Physical review letters》1990,65(23):2850-2852
19.
Mohsen Daeimohamad Fardin Kheirandish Khaled Saeedi 《International Journal of Theoretical Physics》2011,50(1):171-180
The dissipative quantum dynamics of a harmonic oscillator in the presence of a deformed bath is investigated. The deformed
bath is modelled by a collection of deformed quantum harmonic oscillators as a generalization of Hopfield model. The transition
probabilities between energy levels of the oscillator are obtained perturbatively and discussed. 相似文献
20.
G. P. Berman A. R. Bishop D. A. R. Dalvit G. V. Shlyapnikov N. Tarkhanov E. M. Timmermans 《International Journal of Theoretical Physics》2008,47(9):2393-2408
We rigorously analyze the stability of the “quasi-classical” dynamics of a Bose-Einstein condensate with repulsive and attractive
interactions, trapped in an effective 1D toroidal geometry. The “classical” dynamics, which corresponds to the Gross-Pitaevskii
mean field theory, is stable in the case of repulsive interaction, and unstable (under some conditions) in the case of attractive
interaction. The corresponding quantum dynamics for observables is described by using a closed system of linear partial differential
equations. In both cases of stable and unstable quasi-classical dynamics the quantum effects represent a singular perturbation
to the quasi-classical solutions, and are described by the terms in these equations which consist of a small quasi-classical
parameter which multiplies high-order “spatial” derivatives. We demonstrate that as a result of the quantum singularity for
observables a convergence of quantum solutions to the corresponding classical solutions exists only for limited times, and
estimate the characteristic time-scales of the convergence. 相似文献