Passive propellant system

The system utilizes a spherical tank structure A separated into two equal volume compartments by a flat bulkhead B. Each compartment has four similar gallery channel legs located in the principal vehicle axes, ensuring that bulk propellant will contact at least one gallery leg during vehicle maneuvers. The forward compartment gallery channel legs collect propellant and feed it into the aft compartment through communication screens which protrude into the aft compartment. The propellant is then collected by the screened gallery channels in the aft compartment and supplied to the propellant outlet. The invention resides in the independent gallery assembly and screen structure by means of which propellant flow from forward to aft compartments is maintained. Liquid surface tension of the liquid on the screens is used to control liquid flow. The system provides gas-free propellants in low or zero-g environments regardless of axial accelerations and propellant orientation in bulk regions of the vessel

Collective Modes of Tri-Nuclear Molecules

A geometrical model for tri-nuclear molecules is presented. An analytical solution is obtained provided the nuclei, which are taken to be prolately deformed, are connected in line to each other. Furthermore, the tri-nuclear molecule is composed of two heavy and one light cluster, the later sandwiched between the two heavy clusters. A basis is constructed in which Hamiltonians of more general configurations can be diagonalized. In the calculation of the interaction between the clusters higher multipole deformations are taken into account, including the hexadecupole one. A repulsive nuclear core is introduced in the potential in order to insure a quasi-stable configuration of the system. The model is applied to three nuclear molecules, namely $^{96}$Sr + $^{10}$Be + $^{146}$Ba, $^{108}$Mo + $^{10}$Be + $^{134}$Te and $^{112}$Ru + $^{10}$Be + $^{130}$Sn.Comment: 24 pages, 9 figure

Mean-Field Treatment of the Many-Body Fokker-Planck Equation

We review some properties of the stationary states of the Fokker - Planck equation for N interacting particles within a mean field approximation, which yields a non-linear integrodifferential equation for the particle density. Analytical results show that for attractive long range potentials the steady state is always a precipitate containing one cluster of small size. For arbitrary potential, linear stability analysis allows to state the conditions under which the uniform equilibrium state is unstable against small perturbations and, via the Einstein relation, to define a critical temperature Tc separating two phases, uniform and precipitate. The corresponding phase diagram turns out to be strongly dependent on the pair-potential. In addition, numerical calculations reveal that the transition is hysteretic. We finally discuss the dynamics of relaxation for the uniform state suddenly cooled below Tc.Comment: 13 pages, 8 figure

Spin dynamics and magnetic interactions of Mn dopants in the topological insulator Bi2_2Te3_3

The magnetic and electronic properties of the magnetically doped topological insulator Bi$_{\rm 2-x}$Mn$_{\rm x}$Te$_3$ were studied using electron spin resonance (ESR) and measurements of static magnetization and electrical transport. The investigated high quality single crystals of Bi$_{\rm 2-x}$Mn$_{\rm x}$Te$_3$ show a ferromagnetic phase transition for $x\geq 0.04$ at $T_{C}\approx 12$ K. The Hall measurements reveal a p-type finite charge-carrier density. Measurements of the temperature dependence of the ESR signal of Mn dopants for different orientations of the external magnetic field give evidence that the localized Mn moments interact with the mobile charge carriers leading to a Ruderman-Kittel-Kasuya-Yosida-type ferromagnetic coupling between the Mn spins of order 2-3 meV. Furthermore, ESR reveals a low-dimensional character of magnetic correlations that persist far above the ferromagnetic ordering temperature

High Energy Neutrinos: Sources and Fluxes

We discuss briefly the potential sources of high energy astrophysical neutrinos and show estimates of the neutrino fluxes that they can produce. A special attention is paid to the connection between the highest energy cosmic rays and astrophysical neutrinos.Comment: 7 pages, 2 figures, submitted to the Proceedings of TAUP 2005 workshop, corrected left panel of figure

Staggered Pairing Phenomenology for UPd_2Al_3 and UNi_2Al_3

We apply the staggered-pairing Ginzburg-Landau phenomenology to describe superconductivity in UPd_2Al_3 and UNi_2Al_3. The phenomenology was applied successfully to UPt_3 so it explains why these materials have qualitatively different superconducting phase diagrams although they have the same point-group symmetry. UPd_2Al_3 and UNi_2Al_3 have a two-component superconducting order parameter transforming as an H-point irreducible representation of the space group. Staggered superconductivity can induce charge-density waves characterized by new Bragg peaks suggesting experimental tests of the phenomenology.Comment: 4 pages, REVTeX, 2 Postscript figure

Shot-noise-limited spin measurements in a pulsed molecular beam

Heavy diatomic molecules have been identified as good candidates for use in electron electric dipole moment (eEDM) searches. Suitable molecular species can be produced in pulsed beams, but with a total flux and/or temporal evolution that varies significantly from pulse to pulse. These variations can degrade the experimental sensitivity to changes in spin precession phase of an electri- cally polarized state, which is the observable of interest for an eEDM measurement. We present two methods for measurement of the phase that provide immunity to beam temporal variations, and make it possible to reach shot-noise-limited sensitivity. Each method employs rapid projection of the spin state onto both components of an orthonormal basis. We demonstrate both methods using the eEDM-sensitive H state of thorium monoxide (ThO), and use one of them to measure the magnetic moment of this state with increased accuracy relative to previous determinations.Comment: 12 pages, 6 figure

Status of neutrino astronomy

Astrophysical neutrinos can be produced in proton interactions of charged cosmic rays with ambient photon or baryonic fields. Cosmic rays are observed in balloon, satellite and air shower experiments every day, from below 1e9 eV up to macroscopic energies of 1e21 eV. The observation of different photon fields has been done ever since, today with detections ranging from radio wavelengths up to very high-energy photons in the TeV range. The leading question for neutrino astronomers is now which sources provide a combination of efficient proton acceleration with sufficiently high photon fields or baryonic targets at the same time in order to produce a neutrino flux that is high enough to exceed the background of atmospheric neutrinos. There are only two confirmed astrophysical neutrino sources up to today: the sun and SuperNova 1987A emit and emitted neutrinos at MeV energies. The aim of large underground Cherenkov telescopes like IceCube and KM3NeT is the detection of neutrinos at energies above 100 GeV. In this paper, recent developments of neutrino flux modeling for the most promising extragalactic sources, gamma ray bursts and active galactic nuclei, are presented.Comment: Talk given at Neutrino 2008, Christchurch (New Zealand) 6 pages, 4 figures, 1 tabl

Status of neutrino astronomy

Astrophysical neutrinos can be produced in proton interactions of charged cosmic rays with ambient photon or baryonic fields. Cosmic rays are observed in balloon, satellite and air shower experiments every day, from below 1e9 eV up to macroscopic energies of 1e21 eV. The observation of different photon fields has been done ever since, today with detections ranging from radio wavelengths up to very high-energy photons in the TeV range. The leading question for neutrino astronomers is now which sources provide a combination of efficient proton acceleration with sufficiently high photon fields or baryonic targets at the same time in order to produce a neutrino flux that is high enough to exceed the background of atmospheric neutrinos. There are only two confirmed astrophysical neutrino sources up to today: the sun and SuperNova 1987A emit and emitted neutrinos at MeV energies. The aim of large underground Cherenkov telescopes like IceCube and KM3NeT is the detection of neutrinos at energies above 100 GeV. In this paper, recent developments of neutrino flux modeling for the most promising extragalactic sources, gamma ray bursts and active galactic nuclei, are presented.Comment: Talk given at Neutrino 2008, Christchurch (New Zealand) 6 pages, 4 figures, 1 tabl