An arm length stabilization system for KAGRA and future gravitational-wave detectors

Modern ground-based gravitational wave (GW) detectors require a complex interferometer configuration with multiple coupled optical cavities. Since achieving the resonances of the arm cavities is the most challenging among the lock acquisition processes, the scheme called arm length stabilization (ALS) had been employed for lock acquisition of the arm cavities. We designed a new type of the ALS, which is compatible with the interferometers having long arms like the next generation GW detectors. The features of the new ALS are that the control configuration is simpler than those of previous ones and that it is not necessary to lay optical fibers for the ALS along the kilometer-long arms of the detector. Along with simulations of its noise performance, an experimental test of the new ALS was performed utilizing a single arm cavity of KAGRA. This paper presents the first results of the test where we demonstrated that lock acquisition of the arm cavity was achieved using the new ALS. We also demonstrated that the root mean square of residual noise was measured to be 8.2 Hz in units of frequency, which is smaller than the linewidth of the arm cavity and thus low enough to lock the full interferometer of KAGRA in a repeatable and reliable manner

A Hardy's Uncertainty Principle Lemma in Weak Commutation Relations of Heisenberg-Lie Algebra

In this article we consider linear operators satisfying a generalized commutation relation of a type of the Heisenberg-Lie algebra. It is proven that a generalized inequality of the Hardy's uncertainty principle lemma follows. Its applications to time operators and abstract Dirac operators are also investigated

Occupation probability of harmonic-oscillator quanta for microscopic cluster-model wave functions

We present a new and simple method of calculating the occupation probability of the number of total harmonic-oscillator quanta for a microscopic cluster-model wave function. Examples of applications are given to the recent calculations including $\alpha+n+n$-model for $^6$He, $\alpha+t+n+n$-model for $^9$Li, and $\alpha+\alpha+n$-model for $^9$Be as well as the classical calculations of $\alpha+p+n$-model for $^6$Li and $\alpha+\alpha+\alpha$-model for $^{12}$C. The analysis is found to be useful for quantifying the amount of excitations across the major shell as well as the degree of clustering. The origin of the antistretching effect is discussed.Comment: 9 page

Electronic properties of the novel 4d metallic oxide SrRhO3

The novel 4d perovskite compound SrRhO3 was investigated by isovalent doping studies. The solubility limits of Ca and Ba onto Sr-site were below 80% and 20%, respectively. Although SrRhO3 was chemically compressed, approximately 5.7% by the Ca doping, no significant influence was observed on the magnetic and electrical properties.Comment: To be published in a special issue of Physica B (the proceedings of LT23

Derivation of a large isotropic diffuse sky emission component at 1.25 and 2.2um from the COBE/DIRBE data

Using all-sky maps obtained with COBE/DIRBE, we reanalyzed the diffuse sky brightness at 1.25 and 2.2 um, which consists of zodiacal light, diffuse Galactic light (DGL), integrated starlight (ISL), and isotropic emission including the extragalactic background light. Our new analysis including an improved estimate of the DGL and the ISL with the 2MASS data showed that deviations of the isotropic emission from isotropy were less than 10% in the entire sky at high Galactic latitude (|b|>35). The result of our analysis revealed a significantly large isotropic component at 1.25 and 2.2 um with intensities of 60.15 +/- 16.14 and 27.68 +/- 6.21 nWm-2sr-1, respectively. This intensity is larger than the integrated galaxy light, upper limits from gamma-ray observation, and potential contribution from exotic sources (i.e., Population III stars, intrahalo light, direct collapse black holes, and dark stars). We therefore conclude that the excess light may originate from the local universe; the Milky Way and/or the solar system.Comment: ApJ accepte

Discovery of Metastable Helium Absorption Lines in V1280 Scorpii

We report the discovery of blue-shifted metastable He I* absorption lines at 3188 A and 3889 A with multiple components on high-resolution spectra (R ~ 60,000) of V1280 Scorpii. Similar multiple absorption lines associated with Na I D doublet and Ca II H and K are observed. Na I D doublet absorption lines have been observed since 2009, while the metastable He I* absorption lines were absent in 2009 and were detected in 2011 (four years after the burst). We find different time variations in depths and velocities of blue-shifted absorption components among He I*, Na I, and Ca II. The complex time evolutions of these lines can be explained by assuming changes in density and recombination/ionization rate when the ejecta expand and the photosphere contracts to become hotter. The multiple absorption lines originate in the ejected materials consisting of clumpy components, which obscure a significant part of the continuum emitting region. We estimate the total mass of the ejected material to be on the order of ~ 10^{-4} Mo, using metastable He I* 3188 and 3889 absorption lines.Comment: 8 pages, 8 figures, accepted for publication in PAS

The Experimental plan of the 4m Resonant Sideband Extraction Prototype for The LCGT

The 4m Resonant Sideband Extraction (RSE) interferometer is a planned prototype of the LCGT interferometer. The aim of the experiment is to operate a powerrecycled Broadband RSE interferometer with suspended optics and to achieve diagonalization of length signals of the central part of the interferometer directly through the optical setup. Details of the 4m RSE interferometer control method as well as the design of the experimental setup will be presented