ABSTRACT
Cosmic strings are potential gravitational-wave (GW) sources that can be probed by pulsar timing arrays (PTAs). In this work we develop a detection algorithm for a GW burst from a cusp on a ...cosmic string, and apply it to Parkes PTA data. We find four events with a false alarm probability less than 1 per cent. However further investigation shows that all of these are likely to be spurious. As there are no convincing detections we place upper limits on the GW amplitude for different event durations. From these bounds we place limits on the cosmic string tension of Gμ ∼ 10−5, and highlight that this bound is independent from those obtained using other techniques. We discuss the physical implications of our results and the prospect of probing cosmic strings in the era of Square Kilometre Array.
Abstract
KAGRA is a newly built gravitational wave observatory, a laser interferometer with a 3 km arm length, located at Kamioka, Gifu, Japan. In this series of articles we present an overview of ...the baseline KAGRA, for which we finished installing the designed configuration in 2019. This article describes the method of calibration (CAL) used for reconstructing gravitational wave signals from the detector outputs, as well as the characterization of the detector (DET). We also review the physical environmental monitoring (PEM) system and the geophysics interferometer (GIF). Both are used for characterizing and evaluating the data quality of the gravitational wave channel. They play important roles in utilizing the detector output for gravitational wave searches. These characterization investigations will be even more important in the near future, once gravitational wave detection has been achieved, and in using KAGRA in the gravitational wave astronomy era.
•High-speed 2D temperature profiles were obtained for laser melted W spots.•Laser energy absorption coefficients above W melting point were measured.•Several observations indicated the W surface ...bubbling at ∼5000K in UHV.
The energy absorption coefficient of tungsten surface (W) for 1064nm Nd:YAG laser was measured as a function of the induced energy. Result was confirmed by the reference spectral emissivity up to the melting point. Then, two non-contact surface temperature measurement diagnostics, a pyrometer measurement and a two-dimensional (2D) temperature measurement, were constructed for the laser-melted W spot. The 2D temperature profile was obtained by analyzing two-color images from a high-speed camera with an image splitter and a long-distance microscope. An OpenCV based program was developed for corrections on the tilted angle view and wavelength dependence of the captured intensities. W surface bubbling at the surface temperature near 5000K was indicated by high-speed camera images, unstable temperature developments, asymmetric temperature profiles, and the postmortem surface observations.
Overview of KAGRA: KAGRA science Akutsu, T; Arai, K; Aritomi, N ...
Progress of theoretical and experimental physics,
05/2021, Letnik:
2021, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Abstract
KAGRA is a newly build gravitational wave observatory, a laser interferometer with 3 km arm length, located in Kamioka, Gifu, Japan. In this paper, one of a series of articles featuring ...KAGRA, we discuss the science targets of KAGRA projects, considering not only the baseline KAGRA (current design) but also its future upgrade candidates (KAGRA+) for the near to middle term ($\sim$5 years).
This study reports the development of a loop‐mediated isothermal amplification (LAMP) reaction for the detection of Pythium myriotylum. The primer set targeting the ITS sequence of P. myriotylum ...worked most efficiently at 60°C and allowed the detection of P. myriotylum DNA within 30 min by fluorescence monitoring using a real‐time PCR instrument. The peak denaturing temperature of amplified DNA was about 87·0°C. In specificity tests using eight Pythium myriotylum strains, 59 strains from 39 species of Pythium, 11 Phytophthora strains and eight other soil‐borne pathogens, LAMP gave no cross‐reactions. The detection limit was 100 fg of genomic DNA, which was as sensitive as PCR. LAMP could detect P. myriotylum in hydroponic solution samples, and the results coincided with those of the conventional plating method in almost all cases. The LAMP method established in this study is a simple and sensitive tool for the detection of P. myriotylum. SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows the first LAMP assay for the detection of Pythium myriotylum. The primer set designed from ITS region of P. myriotylum can detect the pathogen in field sample with a fast and convenient method. Analysis of the annealing curve of the LAMP reaction products increases the reliability of the LAMP diagnosis. This study shows that the diagnostic method using the LAMP assay is useful for monitoring P. myriotylum in the field.
Abstract
We apply independent component analysis (ICA) to real data from a gravitational wave detector for the first time. Specifically, we use the iKAGRA data taken in April 2016, and calculate the ...correlations between the gravitational wave strain channel and 35 physical environmental channels. Using a couple of seismic channels which are found to be strongly correlated with the strain, we perform ICA. Injecting a sinusoidal continuous signal in the strain channel, we find that ICA recovers correct parameters with enhanced signal-to-noise ratio, which demonstrates the usefulness of this method. Among the two implementations of ICA used here, we find the correlation method yields the optimal results for the case of environmental noise acting on the strain channel linearly.
PDF
