Numerical Renormalization Group Study of non-Fermi-liquid State on Dilute Uranium Systems

We investigate the non-Fermi-liquid (NFL) behavior of the impurity Anderson model (IAM) with non-Kramers doublet ground state of the f$^2$ configuration under the tetragonal crystalline electric field (CEF). The low energy spectrum is explained by a combination of the NFL and the local-Fermi-liquid parts which are independent with each other. The NFL part of the spectrum has the same form to that of two-channel-Kondo model (TCKM). We have a parameter range that the IAM shows the $- \ln T$ divergence of the magnetic susceptibility together with the positive magneto resistance. We point out a possibility that the anomalous properties of U$_x$Th$_{1-x}$Ru$_2$Si$_2$ including the decreasing resistivity with decreasing temperature can be explained by the NFL scenario of the TCKM type. We also investigate an effect of the lowering of the crystal symmetry. It breaks the NFL behavior at around the temperature, $\delta /10$, where $\delta$ is the orthorhombic CEF splitting. The NFL behavior is still expected above the temperature, $\delta/10$.Comment: 25 pages, 12 figure

Measurement by FIB on the ISS: Two Emissions of Solar Neutrons Detected?

A new type of solar neutron detector (FIB) was launched onboard the Space Shuttle Endeavour on July 16, 2009, and it began collecting data at the International Space Station (ISS) on August 25, 2009. This paper summarizes the three years of observations obtained by the solar neutron detector FIB until the end of July 2012. The solar neutron detector FIB can determine both the energy and arrival direction of neutrons. We measured the energy spectra of background neutrons over the SAA region and elsewhere, and found the typical trigger rates to be 20 counts/sec and 0.22 counts/sec, respectively. It is possible to identify solar neutrons to within a level of 0.028 counts/sec, provided that directional information is applied. Solar neutrons were observed in association with the M-class solar flares that occurred on March 7 (M3.7) and June 7 (M2.5) of 2011. This marked the first time that neutrons were observed in M-class solar flares. A possible interpretaion of the prodcution process is provided.Comment: 36 pages, 16 figures, and 3 Tables; Advanced in Astronmy, 2012, Special issue on Cosmic Ray Variablity:Century of Its Obseravtion

A search for solar neutrons on a long duration balloon flight

The EOSCOR 3 detector, designed to measure the flux of solar neutrons, was flown on a long duration RACOON balloon flight from Australia during Jan. through Feb, 1983. The Circum-global flight lasted 22 days. No major solar activity occurred during the flight and thus only an upper limit to the solar flare neutrons flux is given. The atmospheric neutron response is compared with that obtained on earlier flights from Palestine, Texas

Phase diagram of a frustrated mixed-spin ladder with diagonal exchange bonds

Using exact numerical diagonalization and the conformal field theory approach, we study the effect of magnetic frustrations due to diagonal exchange bonds in a system of two coupled mixed-spin $(1,{1/2})$ Heisenberg chains. It is established that relatively moderate frustrations are able to destroy the ferrimagnetic state and to stabilize the critical spin-liquid phase typical for half-integer-spin antiferromagnetic Heisenberg chains. Both phases are separated by a narrow but finite region occupied by a critical partially-polarized ferromagnetic phase.Comment: 5 PRB pages, 7 eps figures, to appear in Phys. Rev.

On the thermodynamic stability and structural transition of clathrate hydrates

Gas mixtures of methane and ethane form structure II clathrate hydrates despite the fact that each of pure methane and pure ethane gases forms the structure I hydrate. Optimization of the interaction potential parameters for methane and ethane is attempted so as to reproduce the dissociation pressures of each simple hydrate containing either methane or ethane alone. An account for the structural transitions between type I and type II hydrates upon changing the mole fraction of the gas mixture is given on the basis of the van der Waals and Platteeuw theory with these optimized potentials. Cage occupancies of the two kinds of hydrates are also calculated as functions of the mole fraction at the dissociation pressure and at a fixed pressure well above the dissociation pressure

Formation of ice nanotube with hydrophobic guests inside carbon nanotube

A composite ice nanotube inside a carbon nanotube has been explored by molecular dynamics and grandcanonical Monte Carlo simulations. It is made from an octagonal ice nanotube whose hollow space contains hydrophobic guest molecules such as neon, argon, and methane. It is shown that the attractive interaction of the guest molecules stabilizes the ice nanotube. The guest occupancy of the hollow space is calculated by the same method as applied to clathrate hydrates