Development of a Neutron Calibration Field with Radioactive Neutron Sources

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Neutron Streaming Through Labyrinth from a Cyclotron Room

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Anterior subtemporal approach for posteriorly projecting posterior communicating artery aneurysms

The original publication is available at www.springerlink.com.ArticleNeurosurgical Review. 30(3): 203-207 (2007)journal articl

Penetration of 33 MeV Neutrons through Iron and Concrete

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Nuclear corrections of parton distribution functions

We report global analysis results of experimental data for nuclear structure-function ratios F_2^A/F_2^{A'} and proton-nucleus Drell-Yan cross-section ratios sigma_{DY}^{pA}/sigma_{DY}^{pA'} in order to determine optimum parton distribution functions (PDFs) in nuclei. An important point of this analysis is to show uncertainties of the distributions by the Hessian method. The results indicate that the uncertainties are large for gluon distributions in the whole x region and for antiquark distributions at x>0.2. We provide a code for calculating any nuclear PDFs at given x and Q^2 for general users. They can be used for calculating high-energy nuclear reactions including neutrino-nucleus interactions, which are discussed at this workshop.Comment: 1+6 pages, LaTeX, 10 eps files, espcrc2.sty, to be published in Nucl. Phys. B Supplements, Proceedings of the Third International Workshop on Neutrino-Nucleus Interactions in the Few GeV Region (NuInt04), Gran Sasso, Italy, March 17-21, 2004. Nuclear PDF library is available at http://hs.phys.saga-u.ac.jp/nuclp.htm

Development of a Two-Dimensional Gaseous Detector for Energy-Selective Neutron Radiography

AbstractEnergy-selective neutron radiography is a new method for studying the fine structure of heavy materials by using pulsed neutron sources. To perform such radiography, precise measurements of temporal information and twodimensional position are essential. Therefore, we developed a gaseous neutron detector using the gas electron multiplier (GEM). In addition, to detect neutrons, a single surface of an aluminium cathode plate and both surfaces of two GEM foils were coated with boron-10. Two normal GEM foils were stacked in a chamber for gas amplification. An anode plate with two-dimensional strips (0.8-mm pitch) was mounted in order to precisely reconstruct neutron incident positions. To allow high-speed data transfer, a compact readout system with new application-specific integrated circuit (ASIC) chips and a field programmable gate array (FPGA) was developed. Finally, several beam tests were conducted with pulsed neutron sources and two interesting applications were demonstrated

Influences of Apolipoprotein E and α1-Antichymotrypsin Genotypes on Regional Cerebral Glucose Metabolism in Alzheimer\u27s Disease

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Evolution of Molecular Abundance in Protoplanetary Disks

We investigate the evolution of molecular abundance in quiescent protoplanetary disks which are presumed to be around weak-line T Tauri stars. In the region of surface density less than $10^2$ g cm$^{-2}$ (distance from the star $\gtrsim 10$ AU in the minimum- mass solar nebula), cosmic rays are barely attenuated even in the midplane of the disk and produce chemically active ions such as He$^+$ and H$_{3}^+$. Through reactions with these ions CO and N$_2$ are finally transformed into CO$_2$, NH$_3$, and HCN. In the region where the temperature is low enough for these products to freeze onto grains, considerable amount of carbon and nitrogen is locked up in the ice mantle and is depleted from the gas phase in a time scale $\lesssim 3\times 10^6$ yr. Oxidized (CO$_2$) ice and reduced (NH$_3$ and hydrocarbon) ice naturally coexist in this part of the disk. The molecular abundance both in the gas phase and in ice mantle varies significantly with the distance from the central star.Comment: 7 pages latex file (using aas2pp4.sty), 3 figures (ps file), to appear in the Astrophysical Journal Letter

A New Type Active Personal Dosemeter with a Solid State Detector

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Comparison of numerical solutions for Q^2 evolution equations

Q^2 evolution equations are important not only for describing hadron reactions in accelerator experiments but also for investigating ultrahigh-energy cosmic rays. The standard ones are called DGLAP evolution equations, which are integrodifferential equations. There are methods for solving the Q^2 evolution equations for parton-distribution and fragmentation functions. Because the equations cannot be solved analytically, various methods have been developed for the numerical solution. We compare brute-force, Laguerre-polynomial, and Mellin-transformation methods particularly by focusing on the numerical accuracy and computational efficiency. An efficient solution could be used, for example, in the studies of a top-down scenario for the ultrahigh-energy cosmic rays.Comment: 12 pages, LaTeX, 13 eps files, Journal of Computational Physics in press, http://hs.phys.saga-u.ac.j