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Ammonia-oxidizing bacteria (AOB) remove intracellular nitrite to prevent its toxicity by a nitrifier denitrification pathway involving two denitrifying enzymes, nitrite reductase and nitric oxide reductase. Here, a Cu-containing nitrite reductase from Nitrosococcus oceani strain NS58, a gammaproteobacterial marine AOB, was expressed in Escherichia coli and purified to homogeneity. Sequence homology analysis indicated that the nitrite reductase from N. oceani was phylogenetically closer to its counterparts from denitrifying bacteria than that of the betaproteobacterium Nitrosomonas europaea. The recombinant enzyme was a homotrimer of a 32 kDa subunit molecule. The enzyme was green in the oxidized state with absorption peaks at 455 nm and 575 nm. EPR spectroscopy indicated the presence of type 2 Cu. Molecular activities and the affinity constant for the nitrite were determined to be 1.6×10(3) s(-1) and 52 μM, respectively.

The angle-correlated energy differential cross-section for 9 Be(n,2n) reaction has been measured with the coincidence detection technique and a pencil-beam DT neutron source of FNS, JAEA. Neutron energy spectra of two emitted neutrons were separately obtained as azimuthal- and axial-angle differential value, which is called TDX. From the measured TDX, double-angle differential cross sections, ADDX, angular differential cross section, ADX, and total cross section, TOX, were deduced. In the TDX, a characteristic energy spectrum for beryllium was seen. The azimuthal ADDX unexpectedly showed a 180deg. symmetrical spectrum, not a flat one. From the result of TOX, JENDL-3.3 and ENDF/B-VI showed a little underestimation by around 10%.

Detailed measurements of α-particle emission double differential cross section for beryllium and carbon with 14-MeV incident neutrons were carried out. In order to identify contributing reaction channels to the 9 Be(n,2n + 2α )a nd 12 C(n,n � + 3α) reactions, we attempted to reproduce energy distributions of emitted particles by Monte Carlo calculations according to reaction kinematics of a lot of channels which contribute to the reactions. As for the 9 Be(n,2n + 2α) reaction, a contribution of the 9 Be(n,α) 6 He* channels and the simultaneous breakup channel was suggested to account for the energy and angular distribution of emitted α-particles and neutrons. As for the 12 C(n,n'+3α) reaction, the 12 C(n,α) 9 Be* channels were largely contributed and well reproduced the experimental data.

We report an experimental observation suggesting plasma channel formation by focusing a relativistic laser pulse into a long-scale-length preformed plasma. The channel direction coincides with the laser axis. Laser light transmittance measurement indicates laser channeling into the high-density plasma with relativistic self-focusing. A three-dimensional particle-in-cell simulation reproduces the plasma channel and reveals that the collimated hot-electron beam is generated along the laser axis in the laser channeling. These findings hold the promising possibility of fast heating a dense fuel plasma with a relativistic laser pulse.

The amplified optical parametric fluorescence (AOPF) from optical parametric chirped-pulse amplifier (OPCPA) was suppressed down to 5/spl times/10/sup 7/ with injecting a residual fundamental pulse of the seeded Q-switch Nd:YAG pumping laser as a quenching beam.

Based on the successful result of fast heating of a shell target with a cone for heating beam injection at Osaka University in 2002 using the PW laser (Kodama et al 2002 Nature 418 933), the FIREX-1 project was started in 2004. Its goal is to demonstrate fuel heating up to 5 keV using an upgraded heating laser beam. For this purpose, the LFEX laser, which can deliver an energy up to10 kJ in a 0.5–20 ps pulse at its full spec, has been constructed in addition to the Gekko-XII laser system at the Institute of Laser Engineering, Osaka University. It has been activated and became operational since 2009. Following the previous experiment with the PW laser, upgraded integrated experiments of fast ignition have been started using the LFEX laser with an energy up to 1 kJ in 2009 and 2 kJ in 2010 in a 1–5 ps 1.053 µm pulse. Experimental results including implosion of the shell target by Gekko-XII, heating of the imploded fuel core by LFEX laser injection, and increase of the neutron yield due to fast heating compared with no heating have been achieved. Results in the 2009 experiment indicated that the heating efficiency was 3–5%, much lower than the 20–30% expected from the previous 2002 data. It was attributed to the very hot electrons generated in a long scale length plasma in the cone preformed with a prepulse in the LFEX beam. The prepulse level was significantly reduced in the 2010 experiment to improve the heating efficiency. Also we have improved the plasma diagnostics significantly which enabled us to observe the plasma even in the hard x-ray harsh environment. In the 2010 experiment, we have observed neutron enhancement up to 3.5 × 107 with total heating energy of 300 J on the target, which is higher than the yield obtained in the 2009 experiment and the previous data in 2002. We found the estimated heating efficiency to be at a level of 10–20%. 5 keV heating is expected at the full output of the LFEX laser by controlling the heating efficiency.

Nonthermal acceleration of relativistic electrons is investigated with an intensive laser pulse. An energy distribution function of energetic particles in the universe or cosmic rays is well represented by a power-law spectrum, therefore, nonthermal acceleration is essential to understand the origin of cosmic rays. A possible candidate for the origin of cosmic rays is wakefield acceleration at relativistic astrophysical perpendicular shocks. The wakefield is considered to be excited by large-amplitude precursor light waves in the upstream of the shocks. Substituting an intensive laser pulse for the large amplitude light waves, we performed a model experiment of the shock environments in a laboratory plasma. An intensive laser pulse was propagated in a plasma tube created by imploding a hollow polystyrene cylinder, as the large amplitude light waves propagated in the upstream plasma at an astrophysical shock. Nonthermal electrons were generated, and the energy distribution functions of the electrons have a power-law component with an index of ~2. We described the detailed procedures to obtain the nonthermal components from data obtained by an electron spectrometer.

High density compression of over 600 times solid density has been achieved by the laser implosion of a hollow shell pellet of deuterated and tritiated plastics (CDT). This is the highest density of material which has ever been realized in a laboratory and corresponds to the density four times higher than the center of the sun.

The LFEX laser system is under construction to realize the principle of the fast ignition in the FIREX-I program. The 3.1-kJ output power of the chirped pulse has been obtained with the main disk amplifier. The 3.3-nm (FWHM) spectral width, which is enough wide for less than 2-ps rise time in pulse compression, was obtained by controlling the seed pulse both of temporally and spectrally with a spatial light modulation. The beam aberration with the main amplification was reduced to less than 0.2[03bb] rms in far field pattern by using two deformable mirrors in the main amplifier.

A large number of hot electrons exceeding the Alfven current can be produced when an ultra-intense laser pulse irradiates a solid target. Self-excited electrostatic and magnetic fields at the target rear could influence the hot electron transport. To investigate the influence, we measure the hot electrons when a pre-plasma is created on the target rear surface and verify an increase of the electron number by a factor of 2 comparing to the no rear plasma case. The increase may be caused because of changes in the electrostatic potential formation process. The retardation of the potential formation is shown using a particle-in-cell simulation. The electron number escaping within the retardation time duration is consistent with our estimation taking the Alfven current into account.

We demonstrated efficient fast heating of a solid wire target attached on a hollow entrant cone target with an ultra-intense laser. The heating temperatures were 1.2-2.1 keV and the heated temperatures were independent of the wire length, implying strong collimation of high energy density electrons produced in an interaction of the ultra-intense laser light with the cone-wire target along the wire. The high energy density electrons propagated along the wire target with maintaining the high energy density of electrons.

We have developed large size diffraction gratings and flat mirrors for large size pulse compressor in LFEX laser system. The required size of grating is 1.8 m, and we use 2 segment system with 91 cm element gratings. The substrates of mirrors and gratings are made of newly developed fused synthetic silica glass for low thermal expansion. The coating on this fused silica substrates are made by the ion beam assisted deposition (IAD) process for low stress coating. The size of element grating is 91 x 42 x 9 cm, and the largest mirror is 86 x 43 x 9 cm. The grating was lured by a novel scanning beam interference lithography system (NanoRuler II) in Plymouth Grating Laboratory in USA. The diffraction efficiency of the grating is better than 95 %, and the wave-front error is better than λ/3 at 632 nm.

A segmented (tiled) grating array is now investigated as a new compressor system for the reason of manufacturing cost of large aperture single grating. However the considerable freedom of motion of segment arises new difficulties on pulse compression and focusing. We constructed a real compressor system using a segmented grating for 15cm aperture laser beam at Gekko MII 100TW laser system, ILE, for investigating several alignment techniques. In order to produce clean pulse shape and focused pattern generated by misalignments or line density mismatching between segment gratings, we applied the image rotation technique as a compressor arrangement. In addition to reduce uncertainness of motion of all optics, we introduced several sensor/detector such as laser level meter or position sensor. It is also shown that a capacitance detector can keep the perfect flatness of segmented grating surface. Using these techniques we demonstrated pulse compression close to Fourier transform limit.

In fast ignition for laser thermonuclear fusion, an ultra intense laser (UIL) pulse irradiates an imploded plasma in order to fast-heat a high-density core with hot electrons generated in laser-plasma interactions. An UIL pulse needs to make plasma channel via laser self-focusing and to propagate through the corona plasma to reach close enough to the core. Hot electrons are used for heating the core. Therefore the propagation of laser light in the high-density plasma region and spatial distribution of hot electron are important in issues in order to study the feasibility of this scheme. We measure the spatial distribution of hot electron when the laser light propagates into the high-density plasma region by self-focusing.

A neutron spectrometer system based on TOF (time of flight) measurement has been studied for determination of fuel density ratio in ITER. The effective collimator diameter was examined against both the saturation of the first detector and measurement efficiency as a spectrometer to achieve the sufficient statistics with required time resolution. Relation between collimator diameter and lower limit measurement efficiency was obtained. Measurement efficiency for every design of TOF spectrometer was calculated with MCNP. Those results indicate that two or three collimators of different size are needed to attain statistics errors within 10 %. An experiment to test the TOF spectrometer and to evaluate the system efficiency was conducted using accelerator neutron source. The result shows that both DD and DT neutrons are measured separately and simultaneously with a fast discrimination electronics system. The fast discrimination improves the counting capability by one order of magnitude.

The laser-driven equation-of-state (EOS) experiments for polyimide are presented. The experiments were performed with emission measurements from the rear sides of shocked targets at up to a laser intensity of 10 1 4 W/cm 2 or higher with 351 nm wavelength and 2.5 ns duration. Polyimide Hugoniot data were obtained up to 0.6 TPa with good accuracy. Applying low-density foam ablator to the EOS unknown material, we also obtained the data at a highest pressure of 5.8 TPa in the nonmetal materials. Those data were in agreement with the theoretical curves.

In the previous studies, the calculated TPRs were overestimated by more than 10 % compared with the measured values in the experiment with a neutron source reflector. In order to confirm that these overestimation are found on other reactions, reaction rate distributions are measured on 197 Au(n,γ) 198 Au and 93 Nb(n,2n) 92m Nb in the ITER TBM mockups with and without a reflector by the activation foil method with DT neutron irradiation experiments. Analyses are performed with MCNP-4C and FENDL-2.1. The ratios of the calculation results to the experimental ones with a reflector are slightly larger than those without a reflector on the reaction rate of 197 Au(n,γ) 198 Au.

McDeLicious is an extension to the MCNP Monte Carlo code with the ability to simulate the generation of source neutrons based on D-Li interaction processes. This paper presents an overview of the M...

The safety analysis for the design of the IFMIF accelerator facility is an ongoing task within the IFMIF project, and the radioprotection analysis is one of the main sections of this task. The high energy beam transport line is a very sensitive section since it contains intense radiation sources. This work presents the radiological analysis of its current layout, and the design of local radiation shields, in order to meet project dose limits. These limits are established to protect workers in neighboring rooms during operation and to ensure unrestricted access for maintenance operations.

This work presents neutronic analyses to support the layout of the high energy beam transport (HEBT) section of the IFMIF neutron source in the framework of the Broader Approach (BA) EVEDA activities. In the HEBT section, neutron back streaming from the lithium target can cause significant damage to accelerator components and result in their activation. In order to estimate the resulting radiation doses, detailed neutron and photon flux distributions inside the Target Interface Room (TIR) and the Radiation Isolation Room (RIR) during operation are evaluated by using the Monte Carlo code McDeLicious, which is an enhancement to MCNP5. The obtained results show that the major contribution to the TIR dose during operation will come from neutrons streaming from the target through the beam ducts and fromsecondaryphotonsproducedintheseparts.Itseems to be impossible to use any semiconductor devices inside TIR, while for mechanical devices there should be no problem. The dose after shutdown due to decay gammas waspreliminarilyestimatedforthebeamductatthemost activated place in TIR. In order to reduce the shutdown dose rate, the use of a low-Mn-content aluminium alloy is proposed.

To examine the accuracy in the neutronics calculations for the Li/V-alloy blanket system without Be neutron multiplier, a fusion neutronics experiment on a Li/V-alloy assembly has been performed wi...

Time evolution of the ablation front displacement between concave and convex regions of a surface corrugated spherical target was observed by flash x‐ray radiography. The results are compared with calculations based on the linearized fluid equation combined with a one‐dimensional simulation to describe the ambient fluid motion. In the analysis, perturbation of the fluid is scaled up to kδ∼2π (k is the perturbation wavenumber and δ is the perturbation amplitude) for the acceleration phase with perturbation mode numbers of l=20 and 30. The practical perturbation of the target requires a relaxation time to form the nominal eigenstate of the Rayleigh–Taylor instability, which results in time delay of instability growth onset.