Status of heavy element research using a gas-filled recoil separator at RIKEN

A gas-filled type of recoil separator for heavy element research was installed at an experimental hall of RIKEN Linear Accelerator facility to realize getting higher intensity of primary beam and long beam time. Performance of the separator was studied using target recoils and various nuclear reactions. The results show the high performance of the separator for heave element research. As an application of the GARIS, production and identification of an isotope of the 110th element ²⁷¹[110] have been performed using the ²⁰⁸Pb(⁶⁴Ni,1n)²⁷¹[110] reaction. Three decay chains coincide well both in decay times and energies with the ones reported by the group of SHIP experiment at GSI, Germany. Our results provide a confirmation of the synthesis of an isotope ²⁷¹[110] of element 110.     

Simultaneous determination of serotonin and 5-hydroxyindole-3-acetic acid in human urine by automated precolumn derivatization and semi-microbore column liquid chromatography with fluorescence detection.

An improved high-performance liquid-chromatographic (HPLC) assay for the simultaneous determination of serotonin (5-HT) and 5-hydroxyindole-3-acetic acid (5-HIAA) in human urine is reported. Following the automated precolumn derivatization of urinary 5-HT and 5-HIAA with benzylamine, the derivatives are separated by isocratic elution on a reversed-phase C18 semi-microbore column, and are fluorometrically detected at an excitation wavelength of 345 nm and an emission wavelength of 480 nm. The detection limits of 5-HT and 5-HIAA are 7 and 5 nmol/l in urine (0.7 and 0.5 fmol/20-microl injection). The proposed automatic method permits a highly selective and sensitive determination of 5-HT and 5-HIAA in human urine without any sample purification.     

Re-hardening of hadron transverse mass spectra in relativistic heavy-ion collisions

We analyze the spectra of pions and protons in heavy-ion collisions at relativistic energies from 2 A GeV to 65+65 A GeV by using a jet-implemented hadron-string cascade model. In this energy region, hadron transverse mass spectra first show softening until SPS energies, and re-hardening may emerge at RHIC energies. Since hadronic matter is expected to show only softening at higher energy densities, this re-hardening of spectra can be interpreted as a good signature of the quark-gluon plasma formation     

Analysis of (π K<Superscript>+</Superscript>) and (K<Superscript>-</Superscript>, K<Superscript>+</Superscript>) hypernuclear production spectra in distorted-wave impulse approximation

We study the hyperon-nucleus potential with distorted-wave impulse wave approximation (DWIA) using the Green's function method. In order to include the nucleon and hyperon potential effects in Fermi averaging, we introduce the local optimal momentum approximation of target nucleons. We can describe the quasi-free Λ , Σ and Ξ production spectra in a better way than in the standard Fermi-averaged t -matrix treatments.     

InGaAs/InAlAs Five Layer Asymmetric Coupled Quantum Well (FACQW) for Ultra-Wideband Ultrafast Optical Modulators

An InGaAs/InAlAs five-layer asymmetric coupled quantum well (FACQW) is expected to show very large electrorefractive index change. n in a wideband transparency region. Band structures of the FACQW are analyzed with Luttinger-Kohn Hamiltonian. The electrorefractive characteristics of the FACQW are discussed.     

High performance a-Si solar cells and new fabrication methods for a-Si solar cells

The super chamber, a separated UHV reaction-chamber system has been developed. A conversion efficiency of 11.7% was obtained for an a-Si solar cell using a high-quality i-layer deposited by the super chamber, and a p-layer fabricated by a photo-CVD method.As a new material, amorphous superlattice-structure films were fabricated by the photo-CVD method for the first time. Superlattice structure p-layer a-Si solar cells were fabricated, and a conversion efficiency of 10.5% was obtained.For the fabrication of integrated type a-Si solar cell modules, a laser pattering method was investigated. A thermal analysis of the multilayer structure was done. It was confirmed that selective scribing for a-Si, TCO and metal film is possible by controlling the laser power density. Recently developed a-Si solar power generation systems and a-Si solar cell roofing tiles are also described.     

Thickness decrease of a grafted polyelectrolyte membrane exposed to shear flow

The effect of the shear flow on the thickness change of a polyelectrolyte membrane grafted onto a glass substrate was directly investigated with a flow cell combined with a confocal laser scanning microscope. The membrane thickness decreased proportionally to an increase in the shear stress of the flow when the shear rate exceeded a critical value of 1 s^?1. The higher the ionic strength was of the fluid, the greater the thinning effect was. The correlation between the critical shear rate and the relaxation of the polymer in the gel membrane was examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2808–2815, 2003     

First measurement of the ϱ spectral function in nuclear collisions

The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158 A GeV In–In collisions. A strong excess of pairs is observed above the yield expected from neutral meson decays. The unprecedented sample size close to 400000 events and the good mass resolution of about 2% made it possible to isolate the excess by subtraction of the decay sources. The shape of the resulting mass spectrum shows some non-trivial centrality dependence, but is largely consistent with a dominant contribution from π⁺π^-→ϱ→μ⁺μ^- annihilation. The associated ϱ spectral function exhibits considerable broadening, but essentially no shift in mass. The p_T-differential mass spectra show the excess to be much stronger at low p_T than at high p_T. The results are compared to theoretical model predictions; they tend to rule out models linking hadron masses directly to the chiral condensate. PACS 25.75.-q; 12.38.Mh; 13.85.Qk     

Tensor analyzing power T 20 of the dd → 3Hen and dd → 3Hp reactions at zero angle for energies 140, 200, and 270 MeV

RIKEN Accelerator Research Facility data on the tensor analyzing power T ₂₀ of the dd → ³Hen and dd → ³Hp reactions at zero angle for deuteron kinetic energies of 140, 200, and 270 MeV are reported. The observed positive sign of T ₂₀ clearly demonstrates the sensitivity to the D/S-wave ratio in the ³He and ³H wave functions in the energy range of the experiment. Data on T ₂₀ for the ³Hen channel are in agreement with those for the ³Hp channel within the experimental errors.