On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

/pdf/the-observation-of-gravitational-waves-from-a-binary-black-58srpupgg9.pdf

The Observation of Gravitational Waves from a Binary Black Hole Merger

日本物理学会誌及びJournal of the Physical Society of Japanの月刊について

There is almost universal agreement among astronomers that most of the mass in the Universe and most of the mass in the Galactic halo is dark. Many lines of reasoning suggest that the dark matter consists of some new, as yet undiscovered, weakly-interacting massive particle (WIMP). There is now a vast experimental effort being surmounted to detect WIMPS in the halo. The most promising techniques involve direct detection in low-background laboratory detectors and indirect detection through observation of energetic neutrinos from annihilation of WIMPs that have accumulated in the Sun and/or the Earth. Of the many WIMP candidates, perhaps the best motivated and certainly the most theoretically developed is the neutralino, the lightest superpartner in many supersymmetric theories. We review the minimal supersymmetric extension of the Standard Model and discuss prospects for detection of neutralino dark matter. We review in detail how to calculate the cosmological abundance of the neutralino and the event rates for both direct- and indirect-detection schemes, and we discuss astrophysical and laboratory constraints on supersymmetric models. We isolate and clarify the uncertainties from particle physics, nuclear physics, and astrophysics that enter at each step in the calculation. We briefly review other related dark-matter candidates and detection techniques.

Supersymmetric Dark Matter

KamLAND has measured the flux of nu;(e)'s from distant nuclear reactors. We find fewer nu;(e) events than expected from standard assumptions about nu;(e) propagation at the 99.95% C.L. In a 162 ton.yr exposure the ratio of the observed inverse beta-decay events to the expected number without nu;(e) disappearance is 0.611+/-0.085(stat)+/-0.041(syst) for nu;(e) energies >3.4 MeV. In the context of two-flavor neutrino oscillations with CPT invariance, all solutions to the solar neutrino problem except for the "large mixing angle" region are excluded.

First Results from KamLAND: Evidence for Reactor Anti-Neutrino Disappearance

The authors studied elastic and inelastic scattering of dark matter with nuclei in huge NaI(Tl) scintillator. The light output response f was measured by fast neutron scattering. The result was f I = 0.05 ± 0.02 for I recoil and f Na = 0.4 ± 0.2 for Na recoil. The low noise (≅5keV) and low BG (≅8counts/day/keV/kg) was achieved by huge (36.5kg/module) NaI(Tl) scintillator. Strong limit for inelastic exitation of 127 I nuclei was studied and strong limit on the local halo density of spin coupled dark matter candidate was derived.

Search for exotic nuclear transition by using the large volume NaI detector of ELEGANTS V.

The isovector electric monopole resonance (IVMR) was studied by the ${}^{60}\mathrm{Ni}{(}^{7}\mathrm{Li}{,}^{7}\mathrm{Be}{)}^{60}\mathrm{Co}$ reaction at 65A MeV and at forward scattering angles including zero degrees. We confirmed the existence of the IVMR at an excitation energy of $20\ifmmode\pm\else\textpm\fi{}2\mathrm{MeV}$ with a width of $10\ifmmode\pm\else\textpm\fi{}2\mathrm{MeV}$ in ${}^{60}\mathrm{Co}$, which is an analog of the ${T}_{0}+1$ isospin component of the IVMR estimated at ${E}_{x}\ensuremath{\approx}31\mathrm{MeV}$ in ${}^{60}\mathrm{Ni}$. The result presently obtained is consistent with previous results using the pion charge-exchange reaction.

Isovector Electric Monopole Resonance in 60 Ni

Double beta decays of 116Cd

The airborne radioactive isotopes from the Fukushima Daiichi nuclear plan t was measured in Tokushima, western Japan. The continuous monitoring has been carried out in Tokushima. From March 23, 2011 the fission product $^{131}$I was observed. The radioisotopes $^{134}$Cs and $^{137}$Cs were also observed in the beginning of April. However the densities were extremely smaller than the Japanese regulation of radioisotopes.

https://web.ias.tokushima-u.ac.jp/bulletin/nat/nat25-4-3.pdf

Measurement of airborne radioactivity from the Fukushima reactor accident in Tokushima, Japan

CANDLES is the project to search for neutrino-less double beta decay (0νββ) of βCa. The observation of 0νββ will prove existence of a massive Majorana neutrino. Now we installed new detector system CANDLES III. Here expected performances of the system for background rejection are presented. It is also described current status of development for the detector system.

/pdf/search-for-neutrino-less-double-beta-decay-with-candles-hsf10sqk78.pdf

Ken-Ichi Fushimi

Papers

Search for exotic nuclear transition by using the large volume NaI detector of ELEGANTS V.

Isovector Electric Monopole Resonance in 60 Ni

Double beta decays of 116Cd

Measurement of airborne radioactivity from the Fukushima reactor accident in Tokushima, Japan

Search for neutrino-less double beta decay with CANDLES