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Oil palms ((Elaeis guineensis Jacq.), have been widely cultivated in Sumatera for over two planting generations and occupied lands with various soil characteristics. In order to investigate microbial diversity in various soil characteristics of oil palm plantation, a molecular analysis called Terminal Restriction Length Polymorphism (T-RFLP) was adopted. The aim of this research was to analyze the bacterial diversity within several oil palm plantations in Sumatera. DNA extraction was performed using soil DNA extraction kit and analysis was performed using fragment analysis following T-RFLP techniques. Data analysis was performed using MICA III public database. The result showed that soil samples were grouped into two clusters based on their chemical properties. Both HhaI and HinfI digestions affected the number of culturable bacteria dominancy. HhaI was more suitable for revealing a possible culturable genera and species abundance. Dominant genera were detected in each cluster. Cluster-2, which consisted of peat soils, was dominated by Clostridium, Burkholderia, Catenibacterium and Pasteuria. As the diversity of microbes reveals soil fertility, the result showed that metagenomic approach could be used to predict soil fertility indicator, in order to improve agricultural practices for oil palm cultivation.

A two-colored digraph is a digraph each of whose arcs is colored by red or blue. An (h,k)-walk in a two-colored digraph is a walk consisting of h red arcs and k blue arcs. A two-colored digraph is primitive provided that for each pair of vertices u and ν there exists an (h,k)-walk from u to ν and from ν to u. The smallest of such positive integer h+k is called the exponent of D(2). Let D(2) be a primitive two colored digraph and let X be a nonempty subset of V(D(2)). The set exponent of X, denoted exp(X,D), is defined to be the smallest positive integer h+k over all nonnegative integers h and k such that for each vertex ν in D(2) there exists an (h,k)-walk from at least one vertex in X to ν. The kth upper generalized exponent of D, F(k,D(2)) is defined to be F(k,D(2)) = max{exp(X,D(2)):|X| = k}. We discuss upper generalized exponents of two-colored primitive extremal ministrong digraphs on n vertices, that is a two-colored digraph consisting of an (n-1)-cycle and an (n-2)-cycle. We present a lower bound f...

From the interaction between the high-contrast (∼more than 1010) 130 TW Ti:sapphire laser pulse and Stainless Steel-2.5 um-thick tape target, proton beam with energies up to 23 MeV with the conversion efficiency of ∼1% is obtained. After plasma mirror installation for contrast improvement, from the interaction between the 30 TW laser pulse and thin-foil target installed on the target holder with the hole whose shape is associated with the design of the well-known Wehnelt electrode of electron-gun, a 7 MeV intense proton beam is controlled dynamically and energy selected by the self-induced quasi-static electric field on the target holder. From the highly divergent beam having continuous spectrum, which are the typical features of the laser-driven proton beams from the interactions between the short-pulse laser and solid target, the spatial distribution of 7 MeV proton bunch is well manipulated to be focused to an small spots with an angular distribution of ∼10 mrad. The number of protons included in the bunch is >106.

The fast electron spectrum was measured for the interaction between the thin foil and the relativistic optical high field. There were two components in the electron spectrum. The higher temperature component was almost explained by the ponderomotive formula Te[MeV] = 0.511(1+I18λμm2/1.37-1). The total electron spectrum including the lower temperature component was also explained by a simple model.

A phase rotation scheme of laser‐produced ions from a solid target by the application of a synchronized RF electric voltage with a pulsed laser has been experimentally investigated with the use of a 100 TW laser, J‐KAREN at JAEA, KPSI. Up to now, energy peaks of up to around 2.0 MeV have been created with a FWHM of 2.6% with good reproducibility using a two‐gap resonator of a quarter wave length with the same frequency as the source laser (∼80 MHz). It is also found that the position of the peak can be well controlled by adjusting the relative phase between the RF electric field and the laser, which is very promising for real applications of such laser‐produced protons. In order to also apply such a phase rotation system for higher energy protons (

The intense isotropic source of multicharged ions, with energy above 300 keV, was produced by femtosecond Ti:Sa laser pulses irradiation (intensity of ∼4×1017 W/cm2) of the He and CO2 gases mixture expanded in supersonic jet. High contrast ionography images have been obtained for 2000 dpi metal mesh, 1 μm polypropylene and 100 nm Zr foils, as well as for different biological objects. Images were recorded on 1 mm thick CR‐39 ion detector placed in contact with back surface of the imaged samples, at the distances 140–160 mm from the plasma source. The obtained spatial resolution of the image was ∼600 nm. A 100 nm object thickness difference was resolved very well for both Zr and polymer foils. The multicharged ion energy for Carbon and Oxygen ions passing through the 1 μm polypropylene foil is estimated to give the energy of more than 300 keV. An almost equal number of ions were measured with total number of about 108 per shot at a different direction from plasma source. Easy production of different sub‐MeV...

As a benchmark experiment to realize a novel and compact laser driven proton accelerator whose significant features are high number density in a short pulse width (∼ns), 2.4 MeV laser driven proton beam is stably focused at 1 Hz repetition rate by using a pair of permanent quadrupole magnets (PMQs) with large apertures whose diameters and field strengths are 3.5 cm and 55 T/m for the first and 2.3 cm and 60 T/m for the second magnets, respectively. The proton beam has been focused to a focal spot of 3×8 mm2 in horizontal and vertical direction (full width at half maximum) at 650∼mm from the source, which is well reproduced by the simulation. The further optimization of the focusing system will sure to pave a way to the novel proton accelerator with which we can investigate the physics appeared in the short time scale as well as that in a high energy density matter, oncology, astrophysics, and so on.

We demonstrate generation of 10–20 MeV/u ions with a compact 4 TW laser using a gas target mixed with submicron clusters, corresponding to tenfold increase in the ion energies compared to previous experiments with solid targets. It is inferred that the high energy ions are generated due to formation of a strong dipole vortex structure. The demonstrated method has a potential to construct compact and high repetition rate ion sources for hadron therapy and other applications.

Generation of high energy negative ions by laser‐plasma interaction is studied theoretically and numerically. New acceleration process called Coulomb implosion mechanism is proposed, which explains efficient acceleration of negative ions from laser‐plasmas. The model is confirmed by using 2‐dimenstional Particle‐in‐Cell simulations. Experimental evidence of negative ion acceleration from cluster target is also presented.

We observe the proton signals with thin‐foil polyimide and copper targets with a high‐intensity Ti:sapphire laser pulse. High‐energy protons with the maximum energy of 2.3 MeV for 7.5 μm thick polyimide target and 1.2 MeV for 3 μm thick copper target are generated at the laser intensity of ∼1×1019 W/cm2 under preformed plasma condition.

At the Advanced Photonics Research Institute (APRI) in Korea, we have a Ti:sapphire laser system which delivers laser pulses of 100‐TW peak power and 32‐fs pulse duration at the repetition rate of 10 Hz. This laser facility is being used to develop compact laser‐driven proton and electron sources. Energetic protons are produced by irradiating the laser pulse on a thin foil target made of copper and polyimide via the target normal sheath acceleration. Proton beam with maximum energy of up to 4 MeV was generated from a polyimide target, and showed high energy conversion efficiency from laser to proton energy. Generation of high‐energy electron beams by the laser wakefield acceleration was performed by focusing the laser pulses onto a 4 mm‐long He‐gas jet. Quasi‐monoenergetic electron beam with peak energy of 45 MeV and maximum energy of 130 MeV was produced. The quality and characteristics of electron beams are strongly dependent on the laser‐plasma interaction length which depends on focal length of the focusing optics.

Protons having energies up to 3.8 MeV are experimentally generated by the p‐polarized, 45 fs, ∼1019 W/cm2 laser pulse interacting with a near‐critical plasma cloud produced by the irradiation of the amplified spontaneous emission (ASE) pedestal at an intensity of ∼1013 W/cm2 onto a 7.5‐μm‐thick polyimide foil target. The emission angle of the high‐energy protons is shifted away from the target normal toward the laser‐propagation direction of 45°. The mechanism which explains the proton generation from the near‐critical plasma cloud is discussed using the two‐dimensional (2D) particle‐in‐cell (PIC) simulation.

金沢大学先端科学・社会共創推進機構, Highlly collimated energetic protons whose energies are up to 4 MeV are generated by an intense femtosecond Titanium Sappheire laser pulse interacting with a 7.5, 12.5, and 25 μm-thick Polyimide tape target and 5 μm-thick copper target. We find no clear difference on the proton spectra from 7.5, 12.5, and 25 μm Polyimide tape target. The highest conversion efficiency from laser energy into protons of ∼3% is observed with a 7.5 μm thick Polyimide target. The quality of the proton beam is good enough to obtain a clear projection image of a mesh having 10 μm line and space structure, installed into the passage of the beam. We obtain clear vertical lines on the proton intensity profiles from the copper target, which are considered to be transferred from the surface of the copper target. From it, we can restrict the size of the proton emitting region to be ∼20μm. © 2008 American Institute of Physics., Embargo Period 12 months

MeV quasi‐mono‐energetic proton beam is produced by a combination of a synchronous radio frequency (rf) electric field and laser‐plasma ion acceleration. The experiment was carried out at the Kansai Photon Science Institute, JAEA, using the Ti:Sapphire laser system called J‐KAREN. The proton beam is emitted normal to the rear surface of the thin polyimide target of the thickness 7.5 μm irradiated at peak intensity of 4×1018 W/cm2. The energy spread is compressed from 100% to less than 11% at FWHM by the rf field. The focusing and defocusing effect of the transverse direction is also observed. These are also studied by a Monte Carlo simulation. The relation between the transverse focusing and the energy spectrum of the phase‐rotated beam is systematically shown by the simulation.

In the sheet metal forming simulation, the shell element widely used is assumed as a plane stress state based on the Mindlin‐Reissner theory. Numerical prediction with the conventional shell element is not accurate when the bending radius is small compared to the sheet thickness. The main reason is because the strain and stress formulation of the conventional shell element does not fit the actual phenomenon. In order to predict precisely the springback of a bent sheet with a severe bend, a measurement method for through‐thickness strain has been proposed. The strain was formulated based on measurement results and calculation results from solid element. Through‐thickness stress distribution was formulated based on the equilibrium. The proposed shell element based on the formulations was newly introduced into the FEM code. The accuracy of this method’s prediction of the springback shape of two bent processes has been confirmed. As a result, it was found that the springback shape even in severe bending can b...

We propose a fast finite element method for the prediction of welding deformation. To decrease the calculation time, this method allows the shell element to be used with the modeling for welding phenomena such as the heat source and joining. For the sake of further time savings, this method includes discrete thermal mechanically coupled analysis, which controls the frequency of mechanical calculations. Reasonable agreement between experimental results and calculation results has been obtained using simulated automotive parts with a short calculation time.

We have detected the electrons accompanying the decay of a long‐lived isomer in 254No, which was produced with the 208Pb(48Ca,2n) reaction. Time and spatial correlations of A = 254 evaporation residues, isomeric electrons and ground‐state α‐particles confirmed the existence of the isomer. The measured electron sum‐energy spectrum favors a Kπ = 7− assignment for the isomer.

Two Gammasphere experiments have been performed in order to establish the possible triaxial nature of strongly deformed (SD) bands in 174Hf. A lifetime measurement confirmed the large deformation of the four previously observed bands in this nucleus. In addition, a thin‐target, high‐statistics experiment was carried out to search for linking transitions between the SD bands. No such transitions, which represent an experimental signature for wobbling modes, were observed. Four new SD bands were found in 174Hf together with a single SD band in 173Hf. These results indicate that the strongly deformed sequences of N ≈ 102 Hf isotopes behave differently than the TSD bands found in Lu nuclei near N = 92. The interpretation of these bands in terms of possible stable triaxial deformation is confronted with the experimental findings and UC predictions.

Low-lying excited states in the very neutron-rich isotope 34Mg were studied via in-beam gamma-ray spectroscopy using a two-step fragmentation reaction. The excited 34Mg nuclei were produced by the projectile fragmentation reaction of a radioactive 36Si beam on a 386 mg/cm2 9Be target at 38 MeV/nucleon. De-excitation gamma rays were detected in coincidence with the reaction products. Two gamma lines associated with 34Mg were observed at 660(10) keV and 1460(20) keV, which are tentatively assigned to the 21+→0g.s.+ and 41+→21+ transitions in 34Mg, respectively. These assignments result in a very low energy of the 21+ state and a E(41+)/E(21+) ratio of about 3.2, suggesting large deformation of 34Mg.

Neutrons with energies E below the Fermi effective potential Ueff∼0.2 μeV are called ultracold neutrons (UCN), which are totally reflected from a surface of material and thus can be stored in a bottle. The UCN in a bottle are of a great advantage for high-precision measurements in fundamental physics with neutrons, where the UCN density ρUCN takes the key role. We have proposed a new method for the production of UCN, which is based on the repeated application of a field-gradient force on a magnetic moment realized with a spatially alternating field and the correlated spin flips. To evaluate the feasibility and performance of the method, a computer simulation of neutron decelerating and transporting processes has been performed. The result indicates that the UCN density ρUCN in a storage bottle in the present method reaches quite large values as ρUCN≈2.2×103 n/cm3 in a realistic condition. An experiment to test the principle and to explore the technical ingredients of the present method is being conducted ...

The electric quadrupole moment of 17B was measured by means of spin polarized fragment beams produced by the projectile fragmentation reaction. The experimental quadrupole moment of 17B was very close to that of neutron p-shell closed nucleus 13B. This result indicates that the neutron effective charge for 17B is considerably smaller than the value commonly used in the sd-shell region.

We propose a new scheme of nuclear spin maser and have performed the experimental and theoretical analyses for its operation, aiming at the significant improvement in sensitivity of neutron electric dipole moment (EDM). The proposed spin-masing scheme incorporates an artificial feedback mechanism, and is applicable to extremely low density systems of spins such as a bottled ensemble of UCNs. Its operation was experimentally demonstrated by using a spin-polarized 129Xe gas as a model substance. The frequency analysis suggests that a frequency precision allowing a neutron EDM search with a sensitivity of 10−28 ecm level is attainable by this maser scheme.