Search

The Tokai-to-Kamioka (T2K) experiment is a second generation long baseline neutrino oscillation experiment which aims at a sensitive search for the nu_e appearance. The main design features of the T2K near detectors located at 280 m from the target are presented. Scintillator counters developed for the T2K near detectors are described. Readout of the counters is provided via WLS fibers embedded into S-shape grooves in a scintillator and viewed from both ends by multi-pixel avalanche photodiodes operating in a limited Geiger mode. A desription, operational principles and the results of tests of photosensors with a sensitive area of 1.1 mm^2 are presented. A time resolution of 1.5 ns, a spatial resolution of 9.9-12.4 cm, and a MIP detection efficiency of more than 99% were obtained for scintillator detectors in a beam test., Comment: 23 pages, 20 figures, 2 tables

Polyurethane (PU) films were prepared by solution-casting after co-polymerization of liquefied woods (LWs) and polymeric methylene diphenylene diisocyanate (PMDI). The resulting PU films had various [NCO]/[OH] ratios ranging from 0.6 to 1.4 and contained 5.0–16.8% dissolved woody components at the [NCO]/[OH] ratio of 1.0. The crosslink densities of the films with [NCO]/[OH] ratios of 0.6–1.4 increased remarkably with increasing [NCO]/[OH] ratio. Similarly, there were large increases in glass transition temperatures ( T g ). These characteristics could be attributed to effective incorporation of PMDI into the LW. The crosslink densities and T g of the PU films prepared at the [NCO]/[OH] ratio of 1.0 increased because the amounts of dissolved woody components in the films increased. It is concluded that the dissolved woody components acted as crosslinking points in PU network formations. The thermal degradation of the PU films at an [NCO]/[OH] ratio of more than 0.8 or with more than 10.6% dissolved wood started above 262°C under an N 2 atmosphere. The thermostability was lost at low crosslink density or with large amount of co-polymerized glycerol structures in the PU networks.

The SciBooNE experiment is designed to measure neutrino cross sections on carbon around 1 GeV region. This article introduces the SciBooNE experiment and reports on the current status of a cross section measurement of the neutral current neutral pion production. We used 0.99 × 10 20 protons on target (POT) for this measurement. After event selections, about 450 signal events are estimated in the Monte Carlo(MC) simulation.

To report quantitative changes in the anterior chamber configuration after small-incision cataract surgery with implantation of a posterior chamber intraocular lens by means of ultrasound biomicroscopy.We examined the anterior chamber configuration of 20 eyes of 20 patients before and 3 months after small-incision cataract surgery (phacoemulsification and aspiration plus foldable intraocular lens implantation through a 3.0- to 4.0-mm self-sealing wound) by means of ultrasound biomicroscopy. The following variables were measured: the anterior chamber depth at the center of the cornea, the angle-opening distance 250 microns from the scleral spur (AOD250), the angle-opening distance 500 microns from the scleral spur (AOD500), and the trabecular-iris angle.The anterior chamber depth at the center of the cornea, AOD250, AOD500, and trabecular-iris angle increased significantly after surgery. The preoperative anterior chamber depth at the center of the cornea and trabecular-iris angle were negatively correlated with the differences between the postoperative and preoperative values (P.01). The preoperative values of all variables examined were negatively correlated with the ratios of the postoperative value to the preoperative value (P.002).The present results showed that small-incision cataract surgery significantly deepened the anterior chamber and widened its angle. The more shallow the preoperative anterior chamber was, the greater the postoperative change of the chamber was; and the more narrow the preoperative angle was, the greater the postoperative change of the angle was.

The charge exchange energy spectrum of beam ions is analyzed in order to study the fast ion confinement. The spectrum is observed to have a depletion, and the effects of the magnetic field, B0 and radial electric field, Er, induced losses on the depletion structures are discussed. Relaxation oscillations of the spectrum are found and a time varying Er is considered to interpret them. A reduction of the depletion structure is observed with electron cyclotron resonance heating (ECRH), and is discussed with the edge Er change and improved ion heating.

This paper describes magnetic equilibrium diagnostics that are installed both inside and outside the vacuum vessel in the toroidal helical device Heliotron E. These magnetic diagnostics consist of Rogowski coils for plasma currents, a diamagnetic loop with compensation coils, a set of full flux loops, a set of partial saddle loops, modulated Rogowski coils with several harmonics, a 2D array of Bp coils and Rogowski coils for bus lines of helical, auxiliary vertical and toroidal coils. Up to now we have routinely obtained the diamagnetic stored energy, toroidal plasma currents, the dipole moment of the Pfirsch-Schluter current, the toroidal voltage, the finite β free-boundary plasma shift and poloidal fluxes. We will describe the signals of measured magnetic fluxes and give some interpretations of the finite β equilibrium.

In the Heliotron E device, fast ion slowing-down processes (deceleration, parallel diffusion, and pitch angle scattering) and the particle loss process are investigated by the measurement temporal behaviour of charge-exchange energy spectra during neutral beam injection (NBI). Using electron cyclotron resonance heating (ECRH), two effects are studied with respect to: (1) extrapolation of slowing-down behaviour to a longer slowing-down time and (2) modification of the ion loss associated with the radial electric field. It is found that (1) there are discrepancies :in the theoretical value in the deceleration and the parallel diffusion processes in NBI + ECRH and ECRH plasmas, and that (2) the particle loss is reduced by the use of ECRH on the NBI plasma.

Observations of resonance lines in the 150 to 400A spectral range provide useful information regarding the behaviour of impurities in a laboratory plasma. Heliotron E emission spectra were recorded using a time-resolved VUV spectroscopy system, and line emission in this range was found to be dominated by impurity radiation from oxygen, carbon, iron and nickel. The magnetic axis of the plasma can be moved relative to the vessel wall, and so a study is presented of the effects of a shift in magnetic axis on the evolution of VUV impurity radiation from different ionic states. Differences in behaviour of different states are analysed by the comparison of observed spectra with plasma coronal equilibrium models.

Changes of impurity behavior and plasma performances by a boronization were investigated in Heliotron E. A 2.45 GHz ECH boronization with helium and decaborane at B=0.046 T was developed. The concentration of H/B atomic ratio in the deposited boron layer was much smaller than that of conventional dc glow discharges and the typical value was 0.1. The light impurity, oxygen and carbon, decreased drastically, but the reduction of the metallic impurity, iron and chromium, was not observed. A small H/B atomic ratio and low levels in the light impurity provided high ion temperature and low density plasma by neutral beam injectin heating.

The characteristics near the last closed flux surface have been studied with a multi-faced Langmuir probe for the edge heated ECH plasmas in Heliotron E. Related to the usually observed degradation of the particle confinement in ECH plasmas (plasma “pump-out” phenomena), we have made the following observations. (a) The characteristics of the plasma flow and electrostatic fluctuations differ with and without the plasma pump-out phenomena, (b) these changes are closely coupled to the loss of the energetic electrons produced by ECH and/or to the resultant electric field, (c) the fluctuation-induced particle flux is well correlated with the degradation of the particle transport.

An edge electron cyclotron heating (ECH) experiment has been performed on the Heliotron-E helical device using 35 GHz and 53 GHz gyrotrons. Transition phenomena have been observed during the 53 GHz edge ECH. The Hα emission and the outflux to the wall dropped, and then the core electron density increased by 20%–60%. The electron stored energy seems to be improved up to 20% after the transition. This phenomenon is found to depend strongly on the edge heating power, the target plasma density and the limiter position. A possible mechanism is discussed in terms of high energy electrons produced by the edge ECH.

The reduction of metallic impurity was found in a carbon limiter configuration in Heliotron E. In order to investigate the impurity penetration into the plasma, the distance between the outermost magnetic surface and the vacuum vessel wall was varied by inserting a carbon rail limiter. The analysis of vacuum ultraviolet impurity spectra and charge exchange neutral fluxes shows that the decrease of the impurity production rates by charge exchange neutral particles is the most probable reason to explain the experimental results. Moreover the electron temperature and density profiles in the limiter shadow provide an ability to screen metallic impurity influxes from the wall.

A comparative study on edge plasma properties between the original “natural” divertor configuration and the material limiter configuration was performed for Heliotron E currentless plasma. By insertion of a carbon rail limiter, the particle and heat fluxes to the divertor footprint were reduced to 20–50% of that in the divertor configuration. Such a reduction of influx resulted in the decrease of metal impurities sputtered from the wall surface. There were no clear differences in the edge density and heat flux profiles for NBI plasma between the limiter and divertor scrape-off. In the limiter configuration, a highly heat loaded area was observed locally on only one side of the limiter head. A perturbation field affected this local heat load.

The decrease in nociceptive threshold has been demonstrated in rats exposed to 24 "C and cold environment (-3 "C) for alternate one hour periods from 10:00-17:00 hours and then kept with cold temperature from 17:00-10:00 hours in the following morning for several days. This model is referred to as the SART (Specific Alternation of Rhythm in Temperature) stress. In the present study, to verify the mechanisms underlying such hyperalgssia, antinociceptive effects of various neuroactive drugs were investigated with the intrathecal injections. The analgesic effects of intrathecal serotonin (5-HT, 30 and 100 nmol/rat), 1-(m-chlorophenyl)-biguanlde hydrochlorlde (mCPBG,10-10Omol/rat, a 5-HT3 agonist) and clonldine (30nmoVrat, an 0~ agonist) in SART stressed rats were significantly greater than in normal rats. (±)-8-hydroxy-2-(di-n-propylamino) tetralin hydrochloride (DPAT, a 5-HT~A agonist) and CGS12066B (a 5-HT,B agonist) produced hyperalgesic action in normal rats. An intrathecal a-methyl 5-HT (a 5-HT2 agonist), phenylephrine (an o¢, agonist), isoproteranol (a I~ agonist) and dopamine had no influence on the nociceptive threshold in both normal and SART stressed rats. On the other hand, the analgesic effects of intrathecal morphine and [D-Ala =, MetS] enkephalinamide (an opioidergic I~ agonist) or [D-Pen~,S]-enkephalin (a ~ agonist) were same degree between SART stressed and normal rats. These results suggest that SART stressed rat exhibit the hyperalgesis resulting from the decreased activltiss of descending monoaminergic pain inhibitory systems, probably mediated by either 5-HT~ serotonergic or o~ noradrenergic receptors in the spinal dorsal horn.