125208242
All-SKY SURVEY HIGH RESOLUTION AIR-SHOWER DETECTOR (ASHRA)
21928235
Development of a 16-inch UV-ray image intensifier tube
We have developed a 16-inch ultraviolet-ray image intensifier (UVII) tube to form the spherical focal surface of the All-sky Survey High Resolution Air-shower Detector (Ashra) telescope, a new air fluorescence and Cerenkov detector to observe TeV gamma rays, very high energy neutrinos, and extremely high energy cosmic rays. The UVII has a very large effective photocathode area of 16-inch diameter and reduces an image size to 1-inch diameter using the electric lens effect. This enables us to use a solid-state imager to take focal surface images in the Ashra telescope. Thus, UVII is a key technology for the Ashra experiment to realize a much lower pixel cost in comparison with other experiments using photomultiplier arrays at the focal surface. The UVII achieves a high resolution of 3.4 Lp/mm at the input window. The output screen of the UVII is made of a fiber optic plate (FOP) with a concave shape to optimize the electric lens configuration under the fixed curvature of input window. This results in an almost uniform resolution over the whole sensitive area. We have adopted a P47 phosphor screen with a 10% decay time of /spl sim/100 ns and have obtained an amplification factor of about 100. In this paper we present the design, construction, and performance of the 16-inch UVII.
120440980
All-sky survey high resolution air-shower detector (Ashra)
16363947
Detecting very high energy neutrinos by the telescope array
Abstract We present the cosmic neutrino detecting potential of the telescope array (TA) for quasi-horizontally downward and upward air showers initiated by very high energy neutrinos penetrating the air and the Earth respectively. We adopted model predictions for extraterrestrial neutrino fluxes from active galactic nuclei, gamma-ray bursts, Greisen photo production, the collapse of topological defects, and Z-bursts. The TA, using a large array of bright and wide field-of-view fluorescence telescopes, can explore these very high energy cosmic neutrino sources.
119251015
Performance of a 20-in. photoelectric lens image intensifier tube
Abstract We have evaluated a 20-in. photoelectric lens image intensifier tube (PLI) to be mounted on the spherical focal surface of the Ashra light collectors, where Ashra stands for All-sky Survey High Resolution Air-shower Detector, an unconventional optical collector complex that images air showers produced by very high energy cosmic-ray particles in a 42°-diameter field of view with a resolution of a few arcminutes. The PLI, the worlds largest image intensifier, has a very large effective photocathode area of 20-in. diameter and reduces an image size to less than 1-in. diameter using the electric lens effect. This enables us to use a solid-state imager to take focal surface images in the Ashra light collector. Thus, PLI is a key technology for the Ashra experiment to realize a much lower pixel cost in comparison with other experiments using photomultiplier arrays at the focal surface. In this paper we present the design and performance of the 20-in. PLI.
30122484
Linearized Gravity on the de Sitter Brane in the Einstein Gauss-Bonnet Theory
We investigate linearized gravity on a single de Sitter brane in the anti-de Sitter (AdS) bulk in the Einstein Gauss-Bonnet (EGB) theory. We find that Einstein gravity is recovered for a high energy brane, i.e., in the limit of a large expansion rate, i.e., for H� � 1, where
119439154
Development of a light source with an injection-locked Nd:YAG laser and a ring-mode cleaner for the TAMA 300 gravitational-wave detector
We have developed a light source suitable for laser interferometric gravitational-wave detectors. The developed light source has high power, TEM00 mode, linear polarization, high frequency stability, and low intensity noise. The light source with the quality is essential for attaining the goal sensitivity in the TAMA 300 and was found to be available for a observation run of a gravitational-wave detector.
119471119
CMB in Open Inflation
The possibility to have an infinite open inflationary universe inside a bubble of a finite size is one of the most interesting realizations extensively discussed in the literature. The original idea was based on the theory of tunneling and bubble formation in the theories of a single scalar field. However, for a long time we did not have any consistent models of this type, so it was impossible to compare predictions of such models with the observational data on the CMB anisotropy. The first semi-realistic model of this type was proposed only very recently, in hep-ph/9807493. Here we present the results of our investigation of the scalar and tensor perturbation spectra and the resulting CMB anisotropy in such models. In all models which we have studied there are no supercurvature perturbations. The spectrum of scalar CMB anisotropies has a minimum at small l and a plateau at l > O(10) for low Omega_0. Meanwhile tensor CMB anisotropies are peaked at l=2. Relative magnitude of the scalar CMB spectra versus tensor CMB spectra at small l depends on the parameters of the models.
115861993
Gauge-invariant cosmological density perturbations
118568748
A Single Field Inflation Model with Large Local Non-Gaussianity
The detection of a large local form of non-Gaussianity is considered to be able to rule out all single field inflation models. This statement is based on the single field consistency condition. Despite the awareness of some implicit assumptions in the derivation of this condition and the demonstration of corresponding examples that illustrate these caveats, to date there is still no explicit and self-consistent model which can serve as a counterexample to this statement. We present such a model in this letter.