Our research proposal entitled ” First detection of Gravitational Waves using Cryogenic Laser Interferometer” was selected as a Specially Promoted Research of JSPS in 24th April 2014. The leader of this research is T.Kajita who is also a PI of KAGRA project.
Excavation of KAGRA’s 7 km Tunnel Now Complete
March 31, 2014
On March 31, 2014, the team of the Large-Scale Cryogenic Gravitational Wave Telescope (KAGRA) completed the excavation of its L-shaped tunnel with two 3 km arms. Including two access tunnels, a total length of 7,697 m has been hollowed out 200 m below the surface of Mt. Ikenoyama in Kamioka—beside the site of Super-Kamiokande—where the construction of a 3-km-scale cryogenic interferometer will soon begin. This interferometer has been designed to directly detect gravitational waves for the first time ever.
KAGRA is an international project involving 231 scientists from 31 institutions, principally operated by ICRR(Institute for Cosmic Ray Research) with two main joint-research institutions, KEK (High energy accelerator research organization) and NAOJ (National Astronomical Observatory). Its aim is to construct 3-km-scale Fabry-Perot Michelson Interferometer underground at Kamioka to detect gravitational waves. Gravitational waves, derived from Einstein’s general theory of relativity, are ripples in the curvature of spacetime that propagate at the speed of light. The first indirect proof of their existence was proposed by Dr. Hulse and Dr. Taylor in 1974 who found a binary system of neutron stars, whose decrease in orbital period was well described by the loss of energy through gravitational radiation. In addition, the astronomers of the BICEP2 experiment at the South Pole recently reported that they had found the signature of primordial gravitational waves imprinted in the B-mode polarization of the Cosmic Microwave Background—further evidence of gravitational waves if confirmed. However, gravitational waves have yet to be detected directly in a form in which their waveforms are evident. The direct detection of gravitational waves will not only validate our understanding of gravity and spacetime but also open up a whole new field of gravitational wave astronomy by enabling the physics of strong gravitational fields to be tested, and enabling direct observations of mysterious objects such as black holes, which are not possible through the observation of electromagnetic waves.
Gravitational waves manifest themselves as extremely small changes in the distance between two points in spacetime. Direct gravitational wave detectors therefore detect a change in the metric. However, even the strongest gravitational waves produced during the merger of binary neutron stars and binary black holes typically cause a variation of length of the size of a hydrogen atom over the distance between the Earth and the Sun. Furthermore, such mergers occur once every 100,000 years in our Galaxy. KAGRA aims to increase the detection frequency to several times per year by employing an ultra high-sensitivity metric-variation detector (that can detect change of one part per trillion of trillion) to expand the observation range to include many galaxies. The key to a successful gravitational wave detector is to minimize background noises such as seismic noise and thermal noise to achieve extremely high sensitivity limited only by the quantum noise of the laser used in the interferometer. KAGRA will be constructed 200 m underground to reduce seismic noise to a hundredth of that at the ground surface, and its mirrors that reflect lasers back and forth will be cooled to temperature of 20 K to reduce thermal noise. KAGRA’s quiet underground environment under Mt. Ikenoyama—also known for its lithological characteristic of hard Hida gneiss rock—is now, after 20 months of excavation, ready to host the world’s most sensitive gravitational wave detector.
KAGRA’s construction started in 2010. The L-shaped tunnel with two 3 km arms and two access tunnels is located 200 m under the surface of Mt. Ikenoyama and has a slope of 0.3% to drain spring water effectively. A construction company, Kashima, started to excavate the access tunnels from the Mozumi area in May 2012, and from the Atotsu area in June 2012. After the excavation of central laboratory area near the Atotsu entrance, the crew split into two groups; one working on the “X-arm”, which extends 3 km in the east-northeast direction, and the other working on the “Y-arm”, extending in the north-northwest direction. The Mozumi crew continued to excavate from the other end of the Y-arm up to a distance of 1,165 m, where they stopped to deal with a possible abnormal amount of spring water at the fault. In December 2013, the Y-arm was finally blasted open from the Atotsu side. Following the completion of the Y-arm, the X-arm continued to be extended from one direction and was completed on March 31, 2014. The full excavation length is 7,697 m. During the construction, no serious lithological issues arose; however, on several occasions an unexpectedly large quantity of spring water hampered smooth operations during the excavation period. Kashima coped with such problems efficiently and professionally, even breaking the national record for the excavation speed by the NATM method, achieving a rate of 359 m per month.
The collaboration plans to install laboratory facilities and the detector components in the coming fiscal year, in preparation for the initial operation at the end of 2015. The full-scale operation is planned to start in JFY2017.
Media Contact for Further Inquiries
PR Office: Misato Hayashida
This announcement are reported in home pages in The University of Tokyo (UT), High energy accelerator research organization (KEK), and National Astronomical Observatory Japan (NAOJ).
UT ： http://www.u-tokyo.ac.jp/public/public01_02_j.html
KEK ： http://www.kek.jp/ja/NewsRoom/Release/20140331150000/
Fig1. The red line shows the seismic vibration level at the ground (Kashiwa Campus) and the green line shows that of 1,000 m underground at Kamioka (CLIO). It has been shown that the seismic vibration level at 200 m below the mountain surface is nearly the level shown in green.
GWADW2014 in which we discuss about the future technique for GW detection will be held in Takayama-city, Gifu-prefecture, Japan from 25th May to 31st May.
The web page is here.
Prof. Somiya’s article has been selected by the Editorial Board of Classical and Quantum Gravity (CQG) to be one of the journal’s Highlights of 2012-2013.
MOU between KAGRA and Dept. of Phys. Hanoi Nat. Univ. of Education
was signed on Oct. 11, 2013. You can find the MOU at;
People from Dept. of Phys. Hanoi Nat. Univ. of Education would join KAGRA in the near future.
The KAGRA talk event is being held in Inotani-sekisho museum in front of the JR inotani station. The lecturer are S.Miyoki, T.Uchiyama, M.Ohashi, S.Kawamura and O.Miyakawa. Especially, in September 8th, two talks about KAGRA will be presented in a festival “Inotani-sekisyo friendly festival “.
Yoshiki high school students visited CLIO and SK in July 9th. This event was also reported in a local newspaper.
The 4th Korea-Japan Workshop was held in Osaka Univ. The web site is here
The doctor thesis of Dr.Izumi who use to be a doctorial student of NAOJ got Braccini Prize 2012 (https://wwwcascina.virgo.infn.it/StefanoBPrize2012.html ).
The award ceremony and lecture will be presented in May 24th 2013 in the
April 19th 2013, an Italy-Japan Workshop about gravitational wave physics has been held in the Embassy of Italy. This is one of events related with Italy year 2013 in Japan for their cultural communication.
Pro. Takahashi was awarded a prize for encouragement of Yamanashi Academy as a promising young researcher in the field of research, education and technology in Yamanashi prefecture.
In Jan/30/2013, the project titled “The construction of Gravitational Wave Astronomy” was selected as one of Core to Core program of JSPS. The leader is Pro.Kawamura.
KAGRA Data analysis school wiil be held in NAOJ during Fev 20th ~ 22th.
You can find application form and information in this page.
3rd Korea-Japan Workshop was held in Dec 21~22 2012.
The program was here.
Pro. Endo, the president of Toyama University visited CLIO. After that young scientists in GW group had a meeting with Pro. Endo, Pro.Moriwaki, Pro.Hirobayashi and Pro.Matsushima who are members of Toyama University at GWPO Kamioka branch building.
ET-KAGRA thermal noise workshop was held in Jena University, Germany.
The workshop report is in here
KAGRA Advisory Board Meeting was held in ICRR Kashiwa Campus. KAGRA EO members were evaluated about the progress of KAGRA, management, and got many suggestions from the Advisory Board members.
In 8th July, a workshop about KAGRA with the department of physics and engineer of Toyama University was held in the Toyama University.
In June 17th, Uchiyama-kun who is ICRR member gave a lecture on KAGRA in the GSA seminar promoted by Hida academy.
New Atotsu tunnel excavation has started. The excavation of Mozumi is also all right.
An External Review for KAGRA project was held in ICRR from 17th April to 20th. The committee chaired by Dr. Michael E. Zucker evaluated the KAGRA designs, progress, and risks of each subgroup and made some advices. We would like to make assure the success of KAGRA project with these External Review’s reports.
KAGRA project PI, Pro.Kajita was awarded a prize of the Japan Academy of
2012 for “the discovery of atmospheric neutrino oscillation”.
Yuki Susa, a member of the KAGRA collaboration at Tokyo Tech,
has been chosen as the representative of master students in
the Department of Physics. Title of his master thesis is
“Optimal signal amplification by weak measurement.”
In 28th February, A Master thesis of T.Sekiguchi got an ICRR Director Award in the ICRR Master and Doctor Thesis Workshop.
His master thesis title is “Modeling and Simulation of Vibration Isolation System”.
Members of the House of Councilors, who belong to committee on education, visited in Kamioka Observatory, Super Kamiokande, XMASS and CLIO.
Thermal noise reduction in CLIO was published in Physical Review Letters.
Summary by Author T.Uchiyama.
“Thermal fluctuation, as evidenced by Brownian motion, has been a well-known phenomenon, and it remains the fundamental limitation for certain ultraprecise measurements such as interferometric gravitational wave (GW) detectors and laser frequency stabilisation using a rigid Fabry-Perot reference cavity. One promising approach for reducing such fluctuations is to use a low-mechanical-loss material at a low temperature. Here, we experimentally demonstrate for the first time a reduction in a mirror’s thermal fluctuation in a GW detector with suspended sapphire mirrors from the Cryogenic Laser Interferometer Observatory (CLIO) at 17K and 18K. The majority of previous efforts to reduce thermal fluctuations in such mirrors have focused on the use of low-loss materials at room temperature. Thus, this achievement provides a new method for overcoming the limitations by thermal fluctuations at room temperature. This cryogenic mirror technology will be used in advanced GW detectors such as KAGRA formerly called the Large-Scale Cryogenic Gravitational Wave Telescope (LCGT), the construction of which began in 2010 in Japan, and the Einstein Telescope in Europe.”
LCGT finally got new nickname “KAGRA”. KA means “Kamioka”, and GRA means Gravity and Gravitational wave.
A detail report is shown in this page.
LCGT ground breaking ceremony was held in Mozumi, Kamioka-cho, Hida-city, Gifu prefecture.
Some photos about ceremony are shown in this page.
LCGT ground breaking ceremony was written up in several newspaper.
(web page on Gifu newspaper).
Korea-Japan Workshop was held in Korea University to promote LCGT project. Collaborations in laser development, vibration isolation, quantum measurement and so on were discussed.
In 2011 November 5th, a lecture entitled ” Challenge to the Mystery of the Universe from Yamanashi !” will be presented by Dr. H. Takahashi and Mr. Tsugane in the Yamanashi-Eiwa school festival.
Please find in detail in,
The European Gravitational Observatory (EGO) and the Institute for Cosmic Ray Research (ICRR) organize a meeting, under the patronage of the Italian Embassy in Tokyo, with the aim to explore the collaboration between Italy and Japan on the Gravitational Wave research with the future interferometric detectors in Italy (advanced Virgo) and Japan(LCGT). The 3rd generation perspectives, thanks to the Einstein Telescope (ET) project will be investigated too and the ELiTES Japanese-European collaborative FP7 project, between ET and LCGT, will be prepared.
University of Tokyo, Kashiwa-campus, Frontier Sciences, Environmental Studies Building, 1st Floor, SF Hall.
Conference Page :
Dr.Miyakawa (ICRR.UT staff) will give a lecture in Nagoya University GCOE program named as “Quest for fundamental principles in the universe”.
The title is “Detection of gravitational waves from underground in Kamioka-mine”.
Please see this page in detail.
In the afternoon July 24th, a science cafe live about LCGT project will
be broadcasted in the home page of Niconico-douga. This program is
organized in cooperation with Asahi newspaper and ICRR UT.
Yoko Ogawa-san who is a japanese famous novelist kindly accepted to be a chairman of a LCGT naming committee, and selected a new hypocrism for LCGT project from about 630 applications. We are very sorry, but please wait until around August~September 2011 for public announcement about this new hypocrism.
An explanatory meeting about LCGT vacuum ducts temporary stock in the Kamioka-railway tunnels will be held in Higashimozumi, Kamioka-cho, Hida-city in 18th May.
A meeting for LCGT new name selection was put off due to 3.11 earthquake will be held in 16th June 2011.
Students and their teachers of Sizhuoka-Kita high school visited Super-Kamiokand, XMASS and CLIO as an event of Super Science High school (SSH). In the morning, they received lectures about SK, XMASS, CLIO and their related physics of neutrino, dark matter, gravitational waves. In the afternoon, they entered the Kamioka mine and visited each facilities.
An explanatory meeting about LCGT vacuum ducts temporary stock in the Kamioka-railway tunnels will be held in Urushiyama, Kamioka-cho, Hida-city in 22nd April.
Yamanashi nichi-nichi newspaper wrote up a company in this region accepted an order for LCGT vacuum system in April 8th.
Gravitational Wave Project Office was established in April 1st 2011.
Gravitational Wave Project Office will be established in April 1st 2011.
An Emeritus professor of Tokyo-toritsu University Ikemoto and members of ABCEJ visited Super-Kamiokande, XMASS and CLIO. The members of ABCEJ are mainly private middle school and high school chemistry teachers around Tokyo.
LCGT MOUs between LIGO and VIRGO were formally concluded.
Mainichi newspaper wrote up the new name application for LCGT.
Physics today Journal wrote up LCGT on the 35th page in December issue.
Staff of Italy embassy visited CLIO with Desalva-sensei.
“Thermal-noise-limited underground interferometer CLIO” was selected as an oustanding article in the Classical and Quantum Gravity hilight of 2009-2010.
The film about the construction of LCGT has started.
The department chief of the academic organization section of the Ministry of Education, Culture, Sports, Science and Technology of Japan visited CLIO. Professor Jim Hough who is one of leader of GEO600 also visited CLIO.
Yoko Ogawa-sensei who is a famous award-winning novelist agreed to be a chairman to decide the new LCGT name.
An assistant researcher recruiting has started.
” A key to understand the Universe – Gravitational Wave detection” by a LCGT collaborator, Dr. Kentaro Somiya was introduced
LCGT call for a new charming name!
A public lecture about LCGT will be held in November 27th. This lecture is one of the National University Festa.
University of Tokyo, Executive Management Program students (20) visited CLIO.
The President of the University of Tokyo, Professor Hamada and the regent of the University of tokyo, Professor Kozima visited CLIO.
Professor Takeda and Assistant Professor Miyamaru and their students (Shinshu University, Department of Science, Physics division, Solid state physics division) visited CLIO.