About the Portability of the DIDASS-Package (an IBM Implementation)

The aim of this paper is to point out the portability of the program package for linear multiple criteria reference point optimization. This should be understood as a step to improve the user-oriented feature of software developed at IIASA and can be an example for further implementations of the software on other computer systems. The actual reason for transferring the DIDASS-package to INSEE is the need for solving problems of medium- and long-term planning for the national economy of France which can be described by dynamic multiple-criteria linear programming models. This paper is an initial note on implementation problems. As soon as there is substantive application in INSEE it will be reported. We first describe the implementation problems, then the solutions and an hypothetical example to demonstrate the workability of the software

Extreme ultraviolet laser excitation of isotopic molecular nitrogen: the dipole-allowed spectrum of ¹⁵N₂ and ¹⁴N¹⁵N

Extreme ultraviolet+ultraviolet (XUV+UV) two-photonionizationspectra of the b ¹Πu(v=0–9), c₃¹Πu(v=0,1), o ¹Πu(v=0,1), c′₄¹Σ⁺u(v=1) and b′¹Σ⁺u(v=1,3–6) states of ¹⁵N₂ were recorded with a resolution of 0.3 cm⁻¹ full-width at half-maximum (FWHM). In addition, the b ¹Πu(v=1,5–7) states of ¹⁴N¹⁵N were investigated with the same laser source. Furthermore, using an ultranarrow bandwidth XUV laser [∼250 MHz (∼0.01 cm⁻¹) FWHM], XUV+UV ionizationspectra of the b ¹Πu(v=0–1,5–7), c₃¹Πu(v=0), o ¹Πu(v=0), c′₄¹Σ⁺u(v=0), and b′¹Σ⁺u(v=1) states of ¹⁵N₂ were recorded in order to better resolve the band-head regions. For ¹⁴N¹⁵N, ultrahigh resolution spectra of the b¹Πu(v=0–1,5–6), c₃¹Πu(v=0), and b′¹Σ⁺u(v=1) states were recorded. Rotational analyses were performed for each band, revealing perturbations arising from the effects of Rydberg-valence interactions in the ¹Πu and ¹Σ⁺u states, and rotational coupling between the ¹Πu and ¹Σ⁺umanifolds. Finally, a comprehensive perturbation model, based on the diabatic-potential representation used previously for ¹⁴N₂, and involving diagonalization of the full interaction matrix for all Rydberg and valence states of ¹Σ⁺u and 1Πu symmetry in the energy window 100 000–110 000 cm⁻¹, was constructed. Term values for ¹⁵N₂ and ¹⁴N¹⁵N computed using this model were found to be in good agreement with experiment.The work was supported by the European Community, under the Access to Research Infrastructures initiative of the Improving Human Potential Program, Contract No. HPRI-CT-1999-00064. K.G.H.B. was supported by the Scientific Visits to Europe Program of the Australian Academy of Science

Is it possible to detect gravitational waves with atom interferometers?

We investigate the possibility to use atom interferometers to detect gravitational waves. We discuss the interaction of gravitational waves with an atom interferometer and analyze possible schemes

Reference frames and rigid motions in relativity: Applications

The concept of rigid reference frame and of constricted spatial metric, given in the previous work [\emph{Class. Quantum Grav.} {\bf 21}, 3067,(2004)] are here applied to some specific space-times: In particular, the rigid rotating disc with constant angular velocity in Minkowski space-time is analyzed, a new approach to the Ehrenfest paradox is given as well as a new explanation of the Sagnac effect. Finally the anisotropy of the speed of light and its measurable consequences in a reference frame co-moving with the Earth are discussed.Comment: 13 pages, 1 figur

Fundamental Physics from Observations of White Dwarf Stars

Variation in fundamental constants provide an important test of theories of grand unification. Potentially, white dwarf spectra allow us to directly observe variation in fundamental constants at locations of high gravitational potential. We study hot, metal polluted white dwarf stars, combining far-UV spectroscopic observations, atomic physics, atmospheric modelling and fundamental physics, in the search for variation in the fine structure constant. This registers as small but measurable shifts in the observed wavelengths of highly ionized Fe and Ni lines when compared to laboratory wavelengths. Measurements of these shifts were performed by Berengut et al (2013) using high-resolution STIS spectra of G191-B2B, demonstrating the validity of the method. We have extended this work by; (a) using new (high precision) laboratory wavelengths, (b) refining the analysis methodology (incorporating robust techniques from previous studies towards quasars), and (c) enlarging the sample of white dwarf spectra. A successful detection would be the first direct measurement of a gravitational field effect on a bare constant of nature. We describe our approach and present preliminary results.Leverhulme Trus

A Mission to Explore the Pioneer Anomaly

The Pioneer 10 and 11 spacecraft yielded the most precise navigation in deep space to date. These spacecraft had exceptional acceleration sensitivity. However, analysis of their radio-metric tracking data has consistently indicated that at heliocentric distances of $\sim 20-70$ astronomical units, the orbit determinations indicated the presence of a small, anomalous, Doppler frequency drift. The drift is a blue-shift, uniformly changing with a rate of $\sim(5.99 \pm 0.01)\times 10^{-9}$ Hz/s, which can be interpreted as a constant sunward acceleration of each particular spacecraft of $a_P = (8.74 \pm 1.33)\times 10^{-10} {\rm m/s^2}$. This signal has become known as the Pioneer anomaly. The inability to explain the anomalous behavior of the Pioneers with conventional physics has contributed to growing discussion about its origin. There is now an increasing number of proposals that attempt to explain the anomaly outside conventional physics. This progress emphasizes the need for a new experiment to explore the detected signal. Furthermore, the recent extensive efforts led to the conclusion that only a dedicated experiment could ultimately determine the nature of the found signal. We discuss the Pioneer anomaly and present the next steps towards an understanding of its origin. We specifically focus on the development of a mission to explore the Pioneer Anomaly in a dedicated experiment conducted in deep space.Comment: 8 pages, 9 figures; invited talk given at the 2005 ESLAB Symposium "Trends in Space Science and Cosmic Vision 2020", 19-21 April 2005, ESTEC, Noordwijk, The Netherland

Test of Special Relativity and Equivalence principle from K Physics

A violation of Local Lorentz Invariance (VLI) and hence the special theory of relativity or a violation of equivalence principle (VEP) in the Kaon system can, in principle, induce oscillations between $K^0$ and $\bar{K}^0$. We construct a general formulation in which simultaneous pairwise diagonalization of mass, momemtum, weak or gravitational eigenstates is not assumed. %and the maximum attainable %velocities of the velocity eigenstates are different. We discuss this problem in a general way and point out that, as expected, the VEP and VLI contributions are indistinguishable. We then insist on the fact that VEP or VLI can occur even when CPT is conserved. A possible CP violation of the superweak type induced by VEP or VLI is introduced and discussed. We show that the general VEP mechanism (or the VLI mechanism, but not both simultaneously), with or without conserved CPT, could be clearly tested experimentally through the energy dependence of the $K_L-K_S$ mass difference and of $\eta_{+-}$, $\eta_{00}$, $\delta$. Constraints imposed by present experiments are calculated.Comment: Latex, 15 pages, 1 figure, version to appear in Phys. Rev.

Quantum Limits in Space-Time Measurements

Quantum fluctuations impose fundamental limits on measurement and space-time probing. Although using optimised probe fields can allow to push sensitivity in a position measurement beyond the "standard quantum limit", quantum fluctuations of the probe field still result in limitations which are determined by irreducible dissipation mechanisms. Fluctuation-dissipation relations in vacuum characterise the mechanical effects of radiation pressure vacuum fluctuations, which lead to an ultimate quantum noise for positions. For macroscopic reflectors, the quantum noise on positions is dominated by gravitational vacuum fluctuations, and takes a universal form deduced from quantum fluctuations of space-time curvatures in vacuum. These can be considered as ultimate space-time fluctuations, fixing ultimate quantum limits in space-time measurements.Comment: 11 pages, to appear in Quantum and Semiclassical Optic

Coherent Bayesian inference on compact binary inspirals using a network of interferometric gravitational wave detectors

Presented in this paper is a Markov chain Monte Carlo (MCMC) routine for conducting coherent parameter estimation for interferometric gravitational wave observations of an inspiral of binary compact objects using data from multiple detectors. The MCMC technique uses data from several interferometers and infers all nine of the parameters (ignoring spin) associated with the binary system, including the distance to the source, the masses, and the location on the sky. The Metropolis-algorithm utilises advanced MCMC techniques, such as importance resampling and parallel tempering. The data is compared with time-domain inspiral templates that are 2.5 post-Newtonian (PN) in phase and 2.0 PN in amplitude. Our routine could be implemented as part of an inspiral detection pipeline for a world wide network of detectors. Examples are given for simulated signals and data as seen by the LIGO and Virgo detectors operating at their design sensitivity.Comment: 10 pages, 4 figure