Negative ion stability calculations Final report

Metastability calculations of energy states of nitrogen negative io

Effect of Anharmonic Libron Interactions on the Single-Libron Spectrum of Solid H\u3csub\u3e2\u3c/sub\u3e and D\u3csub\u3e2\u3c/sub\u3e

The effects of interactions between the elementary excitations (librons) in the orientationally ordered phase of solid H2 and D2 are studied using diagrammatic perturbation theory. This formulation leads naturally to the construction of a renormalized dynamical matrix which includes all anharmonic effects. The cubic anharmonic interactions are by far the dominant ones, and we have calculated the energy shifts of each of the zero-wave-vector libron modes self-consistently to lowest order in the expansion parameter 1/z, where z=12 is the number of nearest neighbors. We find the libron energies (in units of the electrostatic quadrupole-quadrupole coupling constant Γ) to be 11.29 (13.66), 14.07 (17.72), and 19.55 (29.04) with the corresponding harmonic values in parentheses. In contrast to the harmonic theory, these anharmonic results provide a striking fit to the observed Raman spectrum of solid H2 and D2 with reasonable values of Γ, e.g., Γ=0.59 cm−1 for H2 and Γ=0.83 cm−1 for D2. We develop an expression for the Raman intensities in terms of the single-libron spectral weight function. The group-theoretical simplifications in our calculations are discussed in detail in the appendices. The cubic anharmonicity is shown in the accompanying paper to lead to a two-libron spectrum which explains the appearance of extra high-energy lines in the Raman spectrum of solid hydrogen. These effects are shown to be included in the renormalized dynamical matrix in the present approximation. Sum rules for the Raman intensities are derived and are used to check the calculations

k=0 Libron Spectrum for Solid Hydrogen in the Pa3 and C\u3csub\u3emmm\u3c/sub\u3e Structures

The libron wave spectrum at zero wave vector for solid hydrogen in the Pa3 and Cmmm structures is calculated at zero temperature. Interactions other than the electrostatic interactions between molecular quadrupole moments are treated perturbatively. Comparison of our numerical and analytic results for libron frequencies and Raman intensities with the observed Raman spectrum gives strong evidence for the Pa3 structure. The scaling relation between the frequencies of the classical and quantum-librational systems is found to hold for the Pa3 but not for the Cmmm structure. The effects of zero-point librations and libron-libron interactions are studied to lowest order in 1/z, where z is the number of nearest neighbors. Although the static effects are quite small, the shifts in the libron frequencies due to these interactions are of order 15%

Observation of Libron-Libron Interactions in Solid Hydrogen

The anharmonic interactions between librational waves in solid hydrogen are found to lead to significant perturbations in the single-libron spectrum. This large anharmonicity is also responsible for two-libron processes whose frequencies and Raman intensities are calculated. Our results for the one- and two-libron spectra are in excellent agreement with, and hence explain, the optical data

Kinetic and Potential Sputtering of Lunar Regolith: Contribution of Solar-Wind Heavy Ions

Sputtering of lunar regolith by protons as well as solar-wind heavy ions is considered. From preliminary measurements of H+, Ar+1, Ar+6 and Ar+9 ion sputtering of JSC-1A AGGL lunar regolith simulant at solar wind velocities, and TRIM simulations of kinetic sputtering yields, the relative contributions of kinetic and potential sputtering contributions are estimated. An 80-fold enhancement of oxygen sputtering by Ar+ over same-velocity H+, and an additional x2 increase for Ar+9 over same-velocity Ar+ was measured. This enhancement persisted to the maximum fluences investigated is approximately 1016/cm (exp2). Modeling studies including the enhanced oxygen ejection by potential sputtering due to the minority heavy ion multicharged ion solar wind component, and the kinetic sputtering contribution of all solar wind constituents, as determined from TRIM sputtering simulations, indicate an overall 35% reduction of near-surface oxygen abundance. XPS analyses of simulant samples exposed to singly and multicharged Ar ions show the characteristic signature of reduced (metallic) Fe, consistent with the preferential ejection of oxygen atoms that can occur in potential sputtering of some metal oxides

High Consequence Scenarios for North Korean Atmospheric Nuclear Tests with Policy Recommendations for the U.S. Government

The government of North Korea has declared high-altitude EMP-capability to be a “strategic goal” and has also threatened an atmospheric test of a hydrogen bomb. Atmospheric nuclear tests have the potential to cripple satellites and the undersea cable networks critical to communication, and navigation necessary for trans-Pacific trade among the U.S., China, and other nations. When a nuclear warhead is detonated at high altitude, a series of electromagnetic pulses radiate downward within the line of sight of the blast. These pulses can disable equipment with miniature electronics and long conductors. Electric grid controls and transmission systems are especially vulnerable. Intense X-rays and free electrons caused by high-altitude nuclear tests can also disable satellites over large regions of space. After the 1962 Starfish Prime test of EMP effects by the U.S, numerous satellites failed. Based on past missile tests, calculated delivery ranges, EMP coverage areas, and geography, Resilient Societies developed five scenarios for North Korean atmospheric tests. Possible sites for EMP tests include the South Pacific Ocean northeast of French Polynesia, Johnson Atoll southwest of Hawaii, and vicinity of the U.S. territory of Guam. Missile trajectories for all three of these EMP test scenarios overfly populated areas. Missile navigation or nuclear device fuzing errors could place the populations of Japan, Guam, and Hawaii are at risk. All potential EMP test locations could cause disruption to international satellite and undersea cable communications networks. North Korea should not be permitted to conduct an atmospheric nuclear tests since EMP effects on large networks necessary for electric power and international data sharing could have serious worldwide consequences due to the importance of Asia and the Pacific region to the global economy. In the regrettable event that North Korea chooses to conduct atmospheric nuclear tests, U.S. and allied monitoring of EMP effects will be helpful

Coupled-Cluster Approach to Electron Correlations in the Two-Dimensional Hubbard Model

We have studied electron correlations in the doped two-dimensional (2D) Hubbard model by using the coupled-cluster method (CCM) to investigate whether or not the method can be applied to correct the independent particle approximations actually used in ab-initio band calculations. The double excitation version of the CCM, implemented using the approximate coupled pair (ACP) method, account for most of the correlation energies of the 2D Hubbard model in the weak ($U/t \simeq 1$) and the intermediate $U/t$ regions ($U/t \simeq 4$). The error is always less than 1% there. The ACP approximation gets less accurate for large $U/t$ ($U/t \simeq 8$) and/or near half-filling. Further incorporation of electron correlation effects is necessary in this region. The accuracy does not depend on the system size and the gap between the lowest unoccupied level and the highest occupied level due to the finite size effect. Hence, the CCM may be favorably applied to ab-initio band calculations on metals as well as semiconductors and insulators.Comment: RevTeX3.0, 4 pages, 4 figure

The GPS Space Service Volume

Prior to the advent of artificial satellites, the concept of navigating in space and the desire to understand and validate the laws of planetary and satellite motion dates back centuries. At the initiation of orbital flight in 1957, space navigation was dominated by inertial and groundbased tracking methods, underpinned by the laws of planetary motion. It was early in the 1980s that GPS was first explored as a system useful for refining the position, velocity, and timing (PVT) of other spacecraft equipped with GPS receivers. As a result, an entirely new GPS utility was developed beyond its original purpose of providing PVT services for land, maritime, and air applications. Spacecraft both above and below the GPS constellation now receive the GPS signals, including the signals that spill over the limb of the Earth. The use of radionavigation satellite services for space navigation in High Earth Orbits is in fact a capability unique to GPS. Support to GPS space applications is being studied and planned as an important improvement to GPS. This paper discusses the formalization of PVT services in space as part of an overall GPS improvement effort. It describes the GPS Space Service Volume (SSV) and compares it to the Terrestrial Service Volume (TSV). It also discusses SSV coverage with the current GPS constellation, coverage characteristics as a function of altitude, expected power levels, and coverage figures of merit

Spinons in a Crossed-Chains Model of a 2D Spin Liquid

Using Random Phase Approximation, we show that a crossed-chains model of a spin-1/2 Heisenberg spins, with frustrated interchain couplings, has a non-dimerized spin-liquid ground state in 2D, with deconfined spinons as the elementary excitations. The results are confirmed by a bosonization study, which shows that the system is an example of a `sliding Luttinger liquid'. In an external field, the system develops an incommensurate field-induced long range order with a finite transition temperature.Comment: 4 pages, 3 figures; added references; scaling analysis, preserving spin rotational invariance, is extended to finite temperatur

Proposal for an experimental test of the many-worlds interpretation of quantum mechanics

The many-worlds interpretation of quantum mechanics predicts the formation of distinct parallel worlds as a result of a quantum mechanical measurement. Communication among these parallel worlds would experimentally rule out alternatives to this interpretation. A procedure for ``interworld'' exchange of information and energy, using only state of the art quantum optical equipment, is described. A single ion is isolated from its environment in an ion trap. Then a quantum mechanical measurement with two discrete outcomes is performed on another system, resulting in the formation of two parallel worlds. Depending on the outcome of this measurement the ion is excited from only one of the parallel worlds before the ion decoheres through its interaction with the environment. A detection of this excitation in the other parallel world is direct evidence for the many-worlds interpretation. This method could have important practical applications in physics and beyond.Comment: 17 pages, standard LaTex, no pictures, comments welcome, revised version corrects typing error in mixing tim