Semi-realistic nucleon-nucleon interactions with improved neutron-matter properties

New parameter-sets of the semi-realistic nucleon-nucleon interaction are developed, by modifying the M3Y interaction but maintaining the tensor channels and the longest-range central channels. The modification is made so as to reproduce microscopic results of neutron-matter energies, in addition to the measured binding energies of doubly magic nuclei including $^{100}$Sn and the even-odd mass differences of the Z=50 and N=82 nuclei in the self-consistent mean-field calculations. Separation energies of the proton- or neutron-magic nuclei are shown to be in fair agreement with the experimental data. With the new parameter-sets M3Y-P6 and P7, the isotropic spin-saturated symmetric nuclear matter remains stable in the density range as wide as $\rho\lesssim 6\rho_0$, while keeping desirable results of the previous parameter-set on finite nuclei. Isotope shifts of the Pb nuclei and tensor-force effects on shell structure are discussed.Comment: 18 pages including 7 figure

Monoenergetic Neutrino Beam for Long Baseline Experiments

In an electron capture process by a nucleus, emitted neutrinos are monoenergetic. By making use of it, we study how to get a completely monoenergetic neutrino beam in a long baseline experiment.Comment: 9 pages, no figure, som typos are corrected, e.g. equation number quoted in table I is correcte

SeaWiFS technical report series. Volume 6: SeaWiFS technical report series cumulative index: Volumes 1-5

The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) is the follow-on ocean color instrument to the Coastal Zone Color Scanner (CZCS), which ceased operations in 1986, after an eight year mission. SeaWiFS is expected to be launched in August 1993, on the Sea Star satellite, being built by Orbital Sciences Corporation (OSC). The SeaWiFS Project at the NASA/Goddard Space Flight Center (GSFC) has undertaken the responsibility of documenting all aspects of this mission, which is critical to the ocean color and marine science communities. This documentation, entitled the SeaWiFS Technical Report Series, is in the form of NASA Technical Memoranda Number 104566. All reports published are volumes within the series. This volume serves as a reference, or guidebook, to the previous five volumes and consists of four main sections including an index to key words and phrases, a list of all references cited, and lists of acronyms and symbols used. It is our intention to publish a summary index of this type after every five volumes in the series. This will cover the topics published in all previous editions of the indices, that is, each new index will include all of the information contained in the preceding indices

The origin of the terrestrial planets

Three major planets, Venus, Earth, and Mercury formed out of the solar nebula. A fourth planetesimal, Theia, also formed near Earth where it collided in a giant impact, rebounding as the planet Mars. During this impact Earth lost ${\approx}4$\% of its crust and mantle that is now is found on Mars and the Moon. At the antipode of the giant impact, $\approx$60\% of Earth's crust, atmosphere, and a large amount of mantle were ejected into space forming the Moon. The lost crust never reformed and became the Earth's ocean basins. The Theia impact site corresponds to Indian Ocean gravitational anomaly on Earth and the Hellas basin on Mars. The dynamics of the giant impact are consistent with the rotational rates and axial tilts of both Earth and Mars. The giant impact removed sufficient CO$_2$ from Earth's atmosphere to avoid a runaway greenhouse effect, initiated plate tectonics, and gave life time to form near geothermal vents at the continental margins. Mercury formed near Venus where on a close approach it was slingshot into the Sun's convective zone losing 94\% of its mass, much of which remains there today. Black carbon, from CO$_2$ decomposed by the intense heat, is still found on the surface of Mercury. Arriving at 616 km/s, Mercury dramatically altered the Sun's rotational energy, explaining both its anomalously slow rotation rate and axial tilt. These results are quantitatively supported by mass balances, the current locations of the terrestrial planets, and the orientations of their major orbital axes

SeaWiFS Technical Report Series. Volume 7: Cloud screening for polar orbiting visible and infrared (IR) satellite sensors

Methods for detecting and screening cloud contamination from satellite derived visible and infrared data are reviewed in this document. The methods are applicable to past, present, and future polar orbiting satellite radiometers. Such instruments include the Coastal Zone Color Scanner (CZCS), operational from 1978 through 1986; the Advanced Very High Resolution Radiometer (AVHRR); the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), scheduled for launch in August 1993; and the Moderate Resolution Imaging Spectrometer (IMODIS). Constant threshold methods are the least demanding computationally, and often provide adequate results. An improvement to these methods are the least demanding computationally, and often provide adequate results. An improvement to these methods is to determine the thresholds dynamically by adjusting them according to the areal and temporal distributions of the surrounding pixels. Spatial coherence methods set thresholds based on the expected spatial variability of the data. Other statistically derived methods and various combinations of basic methods are also reviewed. The complexity of the methods is ultimately limited by the computing resources. Finally, some criteria for evaluating cloud screening methods are discussed

Evidence against correlations between nuclear decay rates and Earth-Sun distance

We have reexamined our previously published data to search for evidence of correlations between the rates for the alpha, beta-minus, beta-plus, and electron-capture decays of 22Na, 44Ti, 108Agm, 121Snm, 133Ba, and 241Am and the Earth-Sun distance. We find no evidence for such correlations and set limits on the possible amplitudes of such correlations substantially smaller than those observed in previous experiments

Shell structure in neutron-rich Ca and Ni nuclei under semi-realistic mean fields

Shell structure in the neutron-rich Ca and Ni nuclei is investigated by the spherical Hartree-Fock calculations with the semi-realistic $NN$ interactions. Specific ingredients of the effective interaction, particularly the tensor force, often play a key role in the $Z$ dependence of the neutron shell structure. Such examples are found in N=32 and N=40; N=32 becomes magic or submagic in $^{52}$Ca while its magicity is broken in $^{60}$Ni, and N=40 is submagic (though not magic) in $^{68}$Ni but not in $^{60}$Ca. Comments are given on the doubly magic nature of $^{78}$Ni. We point out that the loose binding can lead to a submagic number N=58 in $^{86}$Ni, assisted by the weak pair coupling.Comment: 14 pages including 5 figures, to appear in Physical Review C (Rapid Communication