124082673
Data compression and transmission algorithms for CMS FRPC muon chambers
184667614
Current Status of RENO Experiment
122585803
Construction and properties of acrylic vessels in the RENO detector
Abstract The aim of the RENO (Reactor Experiment for Neutrino Oscillation) is to measure the smallest neutrino mixing angle, θ 13 . The RENO detector consists of four concentric cylindrical layers: the target, γ - catcher , buffer and veto. Acrylic is used for the target and γ - catcher vessels, both of which contain liquid scintillator. Acrylic was chosen because it has good transmittance in the wavelength range of 400 – 430 nm and also does not react with liquid-scintillating solvents. In order to reduce systematic uncertainties, the target volume should be identical to a level of less than 0.1% between the near and far detectors. Furthermore, the acrylic vessel should not have any leaks. In this paper, we investigate the optical properties, design and construction of the acrylic vessels used in the RENO detector.
117078167
Real Time, Directional Measurement of BORON-8 Solar Neutrinos in the Kamiokande-II Detector and Search for Short-Time Variation
121615298
Measurement of the refractive index of the LAB-based liquid scintillator and acrylic at RENO
In this paper, we describe the first measurement of the refractive index of the linear alkyl benzene (LAB)-based liquid scintillator and acrylic used at the Reactor Experiment for Neutrino Oscillation (RENO). The refractive index of a material is an important optical property and the prism spectrometer is the most common device for measuring the refractive index. Using the minimum deviation technique, which requires an exact measurement of the apex angle, we determined the refractive indices at six different wavelengths and then fitted them. We also compared the refractive index of the LAB-based liquid scintillator with the refractive indices of other liquid scintillator solvents commonly used in reactor neutrino experiments.
122749310
RENO: Reactor experiment for neutrino oscillation at Yonggwang
The RENO experiment is under construction to measure the value of the smallest and unknown neutrino mixing angle θ13. The experiment will compare the measured fluxes of electron antineutrinos at two detectors located at 290 m and 1.4 km distances from the center of the Yonggwang nuclear reactors in Korea. It is planned to start data-taking in early 2010. An estimated systematic uncertainty associated with the measurement is less than 0.6%. With three years of data, the experiment will search for the mixing angle values of sin22θ13 down to 0.02.
119219463
MASS DISTRIBUTION IN THE CENTRAL FEW PARSECS OF OUR GALAXY
We estimate the enclosed mass profile in the central 10 pc of the Milky Way by analyzing the infrared photometry and the velocity observations of dynamically relaxed stellar population in the Galactic center. HST/NICMOS and Gemini Adaptive Optics images in the archive are used to obtain the number density profile, and proper motion and radial velocity data were compiled from the literature to find the velocity dispersion profile assuming a spherical symmetry and velocity isotropy. From these data, we calculate the the enclosed mass and density profiles in the central 10 pc of the Galaxy using the Jeans equation. Our improved estimates can better describe the exact evolution of the molecular clouds and star clusters falling down to the Galactic center, and constrain the star formation history of the inner part of the Galaxy.
17174387
N-flation: Observable predictions from the random matrix mass spectrum
We carry out numerical investigations of the perturbations in N-flation models where the mass spectrum is generated by random matrix theory. The tensor-to-scalar ratio and non-Gaussianity are already known to take the single-field values, and so the density perturbation spectral index is the main parameter of interest. We study several types of random field initial conditions and compute the spectral index as a function of mass spectrum parameters. Comparison with microwave anisotropy data from the Wilkinson Microwave Anisotropy Probe shows that the model is currently viable in the majority of its parameter space.
14036761
Dynamics of assisted quintessence
We explore the dynamics of assisted quintessence, where more than one scalar field is present with the same potential. For potentials with tracking solutions, the fields naturally approach the same values — in the context of inflation this leads to the assisted inflation phenomenon where several fields can cooperate to drive a period of inflation though none is able to individually. For exponential potentials, we study the fixed points and their stability confirming results already in the literature, and then carry out a numerical analysis to show how assisted quintessence is realized. For inverse power-law potentials, we find by contrast that there is no assisted behaviour — indeed those are the unique (monotonic) potentials where several fields together behave just as a single field in the same potential. More generally, we provide an algorithm for generating a single-field potential giving equivalent dynamics to multi-field assisted quintessence.
118903790
Extent of Excess Far-Infrared Emission around Luminosity Class III Stars
With the Infrared Space Observatory, we conducted 3 ) 3 pixel imaging photometry of 12 luminosity class III stars, which were previously presumed to have dust particles around them, at far-infrared wave- lengths (60 and 90 km). Eleven out of 12 targets show a peak of excess (above photosphere) far-infrared emission at the location of the star, implying that the dust particles are truly associated with stars. To estimate the size of the excess emission source, the —ux ratio of center to boundary pixels of the 3 ) 3 array was examined. The radius of the dust emission is found to be D3000 to D10,000 AU for a thin shell distribution and D5000 to D25,000 AU for a uniform distribution. We consider three models for the origin of the dust: disintegration of comets, sporadic dust ejection from the star, and emission from nearby interstellar cirrus. The data seem to rule out the —rst model (as far as the ii Kuiper beltlike ˇˇ particles are assumed to be large blackbody grains) but do not enable us to choose between the other two models. Subject headings: circumstellar matterinfrared: starsstars: late-type Zuckerman, Kim, & Liu (1995) correlated the Bright Star Catalogue (Hoffleit & Warren 1991) and the Michigan Spectral Catalogue (Houk, Cowley, & Smith-Moore 1975- 1988) with the IRAS catalogs to determine which, if any, luminosity class III giant stars (—rst-ascent red giants) have associated circumstellar dust particles that radiate at far- infrared (far-IR) wavelengths. Of more than 40,000 class III giant stars in the two catalogs, they found that perhaps 300 have associated dust. The presence of particulate material near premain- sequence, main-sequence, asymptotic giant branch, and supergiant stars may be accounted for in rather straight- forward ways (remnants from the star formation for the for- mer two and mass loss for the latter two). But, there is no obvious way to produce and retain large amounts of dust near —rst-ascent giant stars, which are thought to be too old to still possess much leftover material and insufficiently evolved to have lost a signi—cant amount of their mass. However, one may conjecture that the presence of dust around —rst-ascent giants may involve one or more of the following phenomena: mass loss, binarity, planetary sys- tems, and evaporation of Kuiper belt material. Recently, Jura (1999) has analyzed three models for the dust around eight —rst-ascent giant stars: orbiting dust resulting from the disintegration of comets located in extrasolar analogs of the Kuiper belt, dust sporadically ejected from the star, and emission from particles in the interstellar medium that are accidentally near the star, the ii cirrus hot spot.ˇˇ Among the Zuckerman et al. (1995) list of 100, we observed 12 —rst-ascent giant stars with the PHOT instru- ment of the Infrared Space Observatory (ISO)2 to determine if the excess far-IR emission is truly associated with the stars and to estimate the size of the region that produces the excess far-IR emission.
119294901
E8(8) in Light Cone Superspace
We derive the non-linear action of E-8(8) on the constrained chiral superfield in the light-cone superspace with eight complex Grassmann variables. We construct (to lowest order in the coupling) the sixteen dynamical supersymmetries which generate a Hamiltonian with E-8(8) invariance in three space-time dimensions, and show that it has only interactions with even powers of the coupling constant.