41820397
Fast detection and automatic parameter estimation of a gravitational wave signal with a novel method
The detection of gravitational wave usually requires to match the measurement data with a large number of templates, which is computationally very expensive. Compressed sensing methods allow one to match the data with a small number of templates and interpolate the rest. However, the interpolation process is still computationally expensive. In this article, we designed a novel method that only requires to match the data with a few templates, yet without needing any interpolation process. The algorithm worked well for signals with relatively high SNRs. It also showed promise for low SNRs signals.
119291530
Quantum Wave Equation of Photon
In this paper, we give the quantum wave equations of single photon when it is in the vacuum and medium. With these wave equations, we can study light interference and diffraction with the approach of quantum theory, and also can study the quantum property of photon when it is in a general crystal and photonic crystal. Otherwise, it can be applied in quantum optics and condensed matter feld.
119185203
Likelihood Transform: Making Optimization and Parameter Estimation Easier
Parameterized optimization and parameter estimation is of great importance in almost every branch of modern science, technology and engineering. A practical issue in the problem is that when the parameter space is large and the available data is noisy, the geometry of the likelihood surface in the parameter space is complicated. This makes searching and optimization algorithms computationally expensive, sometimes even beyond reach. In this chapter, we define a likelihood transform (LT) which can make the structure of the likelihood surface much simpler, hence reducing the intrinsic complexity and easing optimization significantly. We demonstrate the properties of LT by applying it to a toy model in gravitational wave data analysis. For the signal with a signal-to-noise ratio 20, LT has made a deterministic template-based search possible for the first time, which turns out to be much more efficient than an exhaustive grid-based search. The method can also be directly applied to similar matched-filtering-based optimization and parameter estimation problems in other fields.
119260979
Octahedron configuration for a displacement noise-cancelling gravitational wave detector in space
We study for the first time a three-dimensional octahedron constellation for a space-based gravitational wave detector, which we call the octahedral gravitational observatory (OGO). With six spacecraft the constellation is able to remove laser frequency noise and acceleration disturbances from the gravitational wave signal without needing LISA-like drag-free control, thereby simplifying the payloads and placing less stringent demands on the thrusters. We generalize LISA’s time-delay interferometry to displacement noise free interferometry (DFI) by deriving a set of generators for those combinations of the data streams that cancel laser and acceleration noise. However, the three-dimensional configuration makes orbit selection complicated. So far, only a halo orbit near the Lagrangian point L1 has been found to be stable enough, and this allows only short arms up to 1400 km. We derive the sensitivity curve of OGO with this arm length, resulting in a peak sensitivity of about \(2\times 10^{-23}\,\) Hz \({}^{-1/2}\) near 100 Hz. We compare this version of OGO to the present generation of ground-based detectors and to some future detectors. We also investigate the scientific potentials of such a detector, which include observing gravitational waves from compact binary coalescences, the stochastic background, and pulsars as well as the possibility to test alternative theories of gravity. We find a mediocre performance level for this short arm length detector, between those of initial and advanced ground-based detectors. Thus, actually building a space-based detector of this specific configuration does not seem very efficient. However, when alternative orbits that allow for longer detector arms can be found, a detector with much improved science output could be constructed using the octahedron configuration and DFI solutions demonstrated in this chapter. Also, since the sensitivity of a DFI detector is limited mainly by shot noise, we discuss how the overall sensitivity could be improved by using advanced technologies that reduce this particular noise source.
16586911
STRONG FIELD EFFECTS ON PULSAR ARRIVAL TIMES: CIRCULAR ORBITS AND EQUATORIAL BEAMS
If a pulsar orbits a supermassive black hole, the timing of pulses that pass close to the hole will show a variety of strong field effects. To compute the intensity and timing of pulses that have passed close to a nonrotating black hole, we introduce here a simple formalism based on two "universal functions," one for the bending of photon trajectories and the other for the photon travel time on these trajectories. We apply this simple formalism to the case of a pulsar in circular orbit that beams its pulses into the orbital plane. In addition to the "primary" pulses that reach the receiver by a more-or-less direct path, we find that there are secondary and higher-order pulses. These are usually much dimmer than the primary pulses, but they can be of comparable or even greater intensity if they are emitted when pulsar is on the side of the hole furthest from the receiver. We show that there is a phase relationship of the primary and secondary pulses that is a probe of the strongly curved spacetime geometry. Analogs of these phenomena are expected in more general configurations, in which a pulsar in orbit around a hole emits pulses that are not confined to the orbital plane.
121165445
Auxiliary functions of the LISA laser link: ranging, clock noise transfer and data communication
The Laser Interferometer Space Antenna (LISA) is required to reduce two important noise sources by post-processing on the ground using time-delay interferometry (TDI): phase noise of the on-board reference clocks and laser frequency noise. To achieve the desired suppression, the TDI algorithm needs measurements of the differential clock noise between any two spacecraft and inter-spacecraft ranging measurements with at least 1 m accuracy, which is beyond the precision of ground-based measurements for deep space missions. Therefore, we need on-board measurements by transmitting clock noise and ranging information between the spacecraft as auxiliary functions of the laser link. This paper reports our current experimental results in clock noise transfer and ranging for noise subtraction via post-processing as well as additional data transfer.
122623840
Coulomb explosions and stopping of molecular ions channeled through carbon nanotubes
We study Coulomb explosions of fast H{sub 2}{sup +} molecules under the channeling conditions through a single-wall carbon nanotube by solving the classical equations of motion for the fragment ions, involving both the repulsive continuum potential of the nanotube wall and the dynamically screened Coulomb repulsion between the two ions. Dynamic polarization of the nanotube electrons, described by a two-dimensional hydrodynamic model, gives rise to the correlated energy losses, a wakelike interaction between the fragment ions, as well as the dynamical image force on each ion. The explosion dynamics is dominated by the bare Coulomb repulsion and it mostly proceeds in the longitudinal direction, accompanied with the radially constrained oscillations of the fragment ions. Strong vicinage effects are found in both the molecule self-energy and its stopping power in the early stages of explosions, but they quickly diminish with the increasing dwell time in a manner which depends on the impact molecule speed and its axis orientation.
121984352
The BES detector
Abstract The Beijing Spectrometer (BES) is a general purpose solenoidal detector at the Beijing Electron Positron Collider (BEPC). It is designed to study exclusive final states in e + e − annihilations at the center of mass energy from 3.0 to 5.6 GeV. This requires large solid angle coverage combined with good charged particle momentum resolution, good particle identification and high photon detection efficiency at low energies. In this paper we describe the construction and the performance of BES detector.
118919025
A New form of Self-duality Equations with Topological Term
Based on the U(1) gauge potential decomposition theory and $\phi$-mapping theory, the topological inner structure of the self-duality (Bogomol'nyi-type) equations are studied. The special form of the gauge potential decomposition is obtained directly from the first of the self-duality equations. Using this decomposition, the topological inner structure of the Chern-Simons-Higgs (CSH) vortex is discussed. Furthermore, we obtain a rigorous self-dual equation with topological term for the first time, in which the topological term has been ignored by other physicists.
298393
Cosmological constant and advanced gravitational wave detectors
Interferometric gravitational wave detectors could measure the frequency sweep of a binary inspiral (characterized by its chirp mass) to high accuracy. The observed chirp mass is the intrinsic chirp mass of the binary source multiplied by (1+z), where z is the redshift of the source. Assuming a nonzero cosmological constant, we compute the expected redshift distribution of observed events for an advanced LIGO detector. We find that the redshift distribution has a robust and sizable dependence on the cosmological constant; the data from advanced LIGO detectors could provide an independent measurement of the cosmological constant. {copyright} {ital 1997} {ital The American Physical Society}
73704898
A New Design for ILC 3.2 km Damping Ring Based on FODO Cell
In this paper, we made a new design for ILC 3.2 km damping ring with 2 arcs based on FODO cell and 2 straight sections which are nearly the same as the new version of the 6.4 km ring DCO4 [1]. This new lattice uses less magnets than DCO4 and less quadrupoles than the present SuperB like lattice [1], and has a freely tunable momentum compaction factor. The work of lattice design and dynamic aperture study will be presented in detail. INTRODUCTION After ILC enter the Technical Design Phase 1 by the end of 2008, the Minimum Machine study [2] based on RDR baseline was launched as the essential strategy of cost-reduction. The term “minimum machine” which try to redesign the machine does not refer to any definable true minimum, but instead is a euphemism for higher level alternative design concepts which promise significant cost-reduction while maintaining the machine performance. With the new machine parameter, a reduction in the number of bunches by a factor of two allows a reduction by the same factor in the circumference of the damping ring, while keeping the current (bunch spacing) in the rings constant. To first order, this could result in a reduction of the damping rings’ cost by almost a factor of two. However, the actual cost savings will depend on the exact lattice design. The design study of ILC 6 km damping ring has started very early and gone through intense competition. The 6.4 km DCO4 based on FODO arc cell is the final version adopted by RDR baseline in 2008. But for the 3.2 km ring, the study which was started by the end of 2008 seems to be immature. The only existent design for the smaller ring is DSB3 based on SuperB lattice. Considering the advantage of FODO lattice such as smaller number of quadrupoles and sextupoles per cell, freely tuable momentum compaction, and better dynamic aperture, we try to make a new design for the smaller ring using FODO arc cell which can also provide a reference for DSB3 design. We named our new design as DMC1 for convenience. GLOBAL CONSIDERATION AND PARAMETER CALCULATION In our design, we adopted the racetrack structure as the 6.4 km baseline design (DCO4). The layout of our 3.2 km damping ring is shown in Figure 1 with the electron and positron beams counter-rotating in the two rings. The advantage of this kind of structure is that the ————————————— injection and extraction beam lines for e+ and erings can be in the same tunnel. Also, the rf section and wigglers are located near each other in order to minimize cryogenic transfer lines, while the rf section must be upstream to avoid the radiation damage. Figure 1: Layout of the 3.2 km ILC damping ring. The first parameter should be considered before lattice design is the damping time. ILC damping ring has a very fast damping time (about 25 ms) which is decided by the 5 Hz machine repetition rate. The damping time for a damping ring is given by [3]