Microscopic state of the positive muon in 2H-NbSe2

The microscopic state of the positive muon in the transition metal dichalcogenide 2H-NbSe₂ was studied using the muon spin relaxation method (μ⁺SR). We found that the μ⁺SR spectra consist of two components. The ratio of the two components and the dynamics of the muon change at 140 K, at the charge-density-wave transition temperature (32 K), and again at the superconducting transition temperature (7 K). We discuss the relation between conduction electron properties and the muon's behavior. This revised version was published online in August 2006 with corrections to the Cover Date.     

He accumulation effect in solid and liquid D-T mixture

This article reports the accumulation effect of the ³He originating from tritium β decay; ³He created in solid remains in it, while one in liquid diffuses and goes out to the vapor gas. We observed this effect through the neutron detection from muon catalyzed fusion phenomenon (μCF), and gave it qualitative understanding, by which the muon transfer rate from (dμ) and (tμ) to helium was derived. This revised version was published online in August 2006 with corrections to the Cover Date.     

Spin dynamics of diluted antiferromagnets MnxMg1-xTiO3 by μSR method

The diluted antiferromagnet Mn_xMg_1-xTiO₃ transforms from the antiferromagnet (AF) to the spin-glass (SG) system at x ∼ 0.6. In order to study the microscopic nature of spin dynamics and ordering, we performed muon spin relaxation measurements for the powder samples of x=1.0∼ 0.55 and examined the concentration dependence. From these results, a drastic change in the spin dynamics was found to occur at x ∼ 0.6. This revised version was published online in August 2006 with corrections to the Cover Date.     

Measurement of the K β /K α ratio for muon alpha sticking X-rays in muon catalyzed d-t fusion at the RIKEN-RAL Muon Facility

At the RIKEN-RAL Muon Facility, μ^- to α sticking K _β X-rays were observed for the first time taking advantage of the pulsed beam structure. The precision of the present measurements was insufficient to distinguish between theoretical models, however the observed K _β /K _α X-ray intensity ratio tends to be smaller than most of these theoretical predictions. This revised version was published online in August 2006 with corrections to the Cover Date.     

57Fe Mössbauer spectroscopic and magnetic studies of R3Fe29-xVx (R=Y,Ce, Nd,Sm, Gd,Tb, and Dy)

Hyperfine Interactions - Mössbauer spectra for Fe atoms in the series of R3Fe29-xVx (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy) compounds were collected at 4.2 K. The ratio of 14.5 T/μB between...     

Cellulose fiber biodegradation in natural waters: river water,brackish water,and seawater

Cellulose, the main component of plant cell walls, is degradable in nature. However, to the best of our knowledge, this is the first report that compares the biodegradability of cellulose fibers with different structures in natural waters. River water, brackish water, and seawater were collected from the Kamo River and Osaka Bay, Japan. Biodegradation of cellulose fibers with different structures and crystallinities, ramie, mercerized ramie, and regenerated cellulose fibers in the collected natural water was investigated in the dark at 20 °C for 30 days. The primary and aerobic ultimate biodegradability were evaluated by weight loss and biochemical oxygen demand (BOD) tests, respectively. In the weight-loss test, cellulose fibers were found to be degraded by more than 50% in any natural water within 30 days. However, in the BOD test, biodegradation was diminished, with values of 40%, 20–30%, and 2–10% in river water, brackish water, and seawater, respectively. These results indicate that cellulose fibers are easily degraded into fine fragments, but it is difficult to cause their ultimate decomposition into water and carbon dioxide. Existence of such a tendency in the degree of biodegradation among the cellulose fibers remains unclear. The molecular weight of cellulose fibers in natural water was also measured during their degradation. The degradation behavior in river water and seawater was observed to be different from that in brackish water. The results thus obtained indicate that the microorganisms and enzymes that degrade cellulose fibers differ depending on the natural water, which influences the degree and mechanism of biodegradation.

     

A collocation method for solving singular integro-differential equations

This paper describes a collocation method for numerically solving Cauchy-type linear singular integro-differential equations. The numerical method is based on the transformation of the integro-differential equation into an integral equation, and then applying a collocation method to solve the latter. The collocation points are chosen as the Chebyshev nodes. Uniform convergence of the resulting method is then discussed. Numerical examples are presented and solved by the numerical techniques.     

Spin dynamics of the 2-dimensional ferromagnetism in the superlattice [MnSb/Sb] probed by positive muons

The spin dynamics of 2-dimensional ferromagnetic monolayers of [MnSb/Sb] were studied by the ⁺SR method using pulsed sub-surface muons with a momentum of 18 – 25 MeV/c. A gradual growth of a static field along the ⁺ spin below 200 K and a divergent increase of the relaxation rate at around 25 K were observed in the 1 monolayer sample, related to the critical fluctuations in this magnetic superlattice.     

Nuclear orientation of Bi isotopes in a ferromagnetic BiMn compound

A method of low-temperature nuclear orientation of bulk amount of Bi was developed utilizing a ferromagnetic compound BiMn. The radioactive isotopes of Bi,²⁰⁷Bi and²⁰⁶Bi, were oriented by this method and the hyperfine field at Bi in BiMn was determined to be ±(940 _?130 ⁺¹⁸⁰ ) kOe. No reorientation effect was observed at the isomers in²⁰⁷Pb and²⁰⁶Pb around 30 mK. The E2/M1 multipole mixing ratios of several γ-transitions in²⁰⁶Pb were determined.     

Long-lived muonium in water revealed by pulsed muons

The relaxation rate of muonium in pure water has been found to be smaller than 0.05 × 10⁶ s^?1. With the aid of pulsed muong. μSR and MuSR measurements have been carried out over a longer time range than ever achieved. The results indicate a stability of thermal muonium in water from 3 to 29°C.