KAGRA
Takaaki Kajita 104th Indian Science Congress Institute for Cosmic Ray Research, The Univ. of Tokyo Jan. 3, 2017 1 Outline
• Introduction • Kamiokande • Super-Kamiokande • Discovery of atmospheric neutrino oscillations • Contribution to the discovery of solar neutrino oscillations: Super-Kamiokane and KamLAND • Future neutrino studies • New research in Kamioka: Gravitational waves • Summary
2 Introduction
3 Where is Kamioka?
4 What are neutrinos? • Neutrinos; • are elementary particles like electrons and quarks, • have no electric charge, • have, like the other particles, 3 types (flavors), namely electron-neutrinos (νe), muon- neutrinos (νµ) and tau-neutrinos (ντ), • are produced in various places, such as the Earth’s atmosphere, …. • can easily penetrate through the Earth, • can, however, interact with matter very rarely. • In the very successful Standard Model of particle physics, neutrinos are assumed to have no mass. Neutrino @NASA 5 Neutrino oscillations If neutrinos have masses, neutrinos change their flavor (type) from one flavor (type) to the other. For example, νµ could oscillate to ντ.
Theoretically predicted by;
Sakata Memorial Archival Library Probability: arXiv:0910.1657 νµ to remain νµ
B. Pontecorvo Probability: S. Sakata, Z. Maki, M. Nakagawa νµ toντ L is the neutrino flight length (km), Wikipedia E is the neutrino energy (GeV). If neutrino mass is smaller, the oscillation length (L/E) gets longer.
Atmospheric Neutrino Oscillations 6 Kamiokande
7 Kamioka Nucleon Decay Experiment (Kamiokande) In the late 1970’s, Grand Unified Theories of elementary particles were proposed. They predicted that protons and neutrons should decay with the lifetime of about 1030 years. Several proton decay experiments began in the early 1980’s. One of them was Kamiokande.
Kamiokande (3000 ton water tank) Detector wall Elec. room
Cherenkov Water system light Photo detectors Charged particle
8 Construction of the Kamiokande detector (spring 1983)
The Kamiokande experiment started in July 1983.
9 Didn’t observe proton decays, but… Kamiokande did not observe proton decays. However, it was found that the detector has a very good performance due to 50 cm diameter photomultiplier tubes that were developed for the Kamiokande experiment.
Solar neutrinos could be observed.
Improvement of the Kamiokande detector to observe solar neutrinos. Initial idea of Super-Kamiokande. (both by M. Koshiba)
(photo by Hamamatsu Photonics Co.) 10 Toward Kamiokande-II (1984-5)
Construction of the bottom outer detector
Construction of the side outer detector (between the steel tank and the rock)
11 SN1987A (Feb. 23, 1987) K. Hirata et al., Phys. Rev. Lett. 58 (1987) 1490. SN1987A (at LMC)
Supernova neutrinos Number of PMT hits
2002 Nobel prize in Physics to Prof. M. Koshiba (The IMB experiment also observed the neutrino signal.) 12 Atmospheric neutrinos
COSMIC INCOMING RAY COSMIC RAYS AIR NUCLEUS
PION MUON ELECTRON 2 muon- neutrinos 1 electron- neutrino
© David Fierstein, originally published in Scientific American, August 1999 13 Atmospheric νµ deficit (1980’s to 90’s) Because atmospheric neutrinos are the most serious background to the proton decay searches, it was necessary to understand atmospheric neutrino interactions. During these studies, a significant deficit of atmospheric νµ events was observed.
Kamiokande (1988, 92, 94)
IMB (1991, 92)
14 Confirmation of solar νe deficit (1989) Solar neutrino data between Jan. 1987 and May 1988: The Kamiokande results on; • Supernova neutrinos (1987) Standard Solar Model • Atmospheric neutrino deficit (1988) • Solar neutrino deficit (1989) were evaluated to be very important.
The construction of the Super- Kamiokande experiment was approved in 1991 by the Japanese government. K. S. Hirata et al., Phys. Rev. Lett. 63 (1989) 16.
15 Super-Kamiokande
16 Super-Kamiokande detector 50,000 ton water Cherenkov detector (22,500 ton fiducial volume)
More than 20 times larger mass
~140 collaborators ４２ｍ
３９ｍ １０００ｍ underground
17 Constructing the Super-Kamiokande detector (spring 1995)
TK
Y. Totsuka
18 Filling water in Super-Kamiokande Jan. 1996
19 Discovery of atmospheric neutrino oscillations
20 Atmospheric neutrinos: What will happen if the νµ deficit is due to neutrino oscillations Cosmic ray
Not long enough ) µ Down-going to oscillate ν remain remain µ Probability Probability ν ( Up-going Long enough to oscillate
1 10 100 1000 104 L(km) for 1GeV neutrinos
A deficit of upward going νµ’s should be observed! Cosmic ray 21 Evidence for neutrino oscillations (Super-Kamiokande @Neutrino ’98) Y. Fukuda et al., PRL 81 (1998) 1562
Super-Kamiokande concluded that the observed zenith angle dependent deficit (and the other supporting data) gave evidence for neutrino oscillations.
22 Contribution to the discovery of solar neutrino oscillations: Super-Kamiokande and KamLAND
http://www.sns.ias.edu/~jnb/ J. N. Bahcall https://www.bnl.gov/bnlweb/raydavis/ R. Davis Jr. http://www.astronomynotes.com/starsun/s4.htm 600 ton
C2Cl4 Pioneering Homestake solar neutrino experiment observed only about 1/3 of the predicted solar neutrinos (1960’s). This problem was confirmed by the subsequent experiments in the 1980’s and 90’s.
24 Solving the solar neutrino problem (2001-2002)
SNO - SNO νeDe pp νe flux ν +ν flux !! Super-K ES µ τ (ν ν ν e + µ + τ νeνe flux) SNO
νe +νµ +ντ νDνpn flux
Flux (106/cm2/sec) 1000 ton of heavy water (D O) Neutrino oscillation: electron neutrinos 2 Art McDonald to the other neutrinos. Photo: K. MacFarlane. Queen's University /SNOLAB 25 KamLAND KamLAND is a 1kton liq. scintillator Many nuclear power stations detector, and was constructed at around KamLAND at the the location of Kamiokande after its distance of about 180 km. completion. Neutrino osc. experiment with reactor neutrinos.
1kton liq. scintillator
@ Research center for neutrino science, Tohoku University
26 Really neutrino oscillations ! KamLAND data on neutrino oscillations from nuclear power stations.
KamLAND PRD 83 (2011) 052002
Atsuto Suzuki
Really neutrino oscillations!
27 What have we learned? Why are neutrinos important?
3rd generation
2nd generation
Neutrinos Quarks 1st generation ？ (with some assumptions) Charged leptons (electrons, etc.)
0.01 1 100 104 106 108 1010 1012 1014 Mass（eV/c2） The neutrino masses are approximately (or more than) 10 billion (10 orders of magnitude) smaller than the corresponding masses of quarks and charged leptons! We believe this is the key to understand the nature at the smallest and the largest scales.
28 Future neutrino studies
29 Neutrino mass
3rd generation
2nd generation ？ 1st generation ？
0.01 1 100 104 106 108 1010 1012 1014 Mass（eV/c2） Or 0.01 1 100 104 106 108 1010 1012 1014 Mass（eV/c2） 30 Future experiments that will tell us the order of the neutrino masses
RENO-50
Hyper-K
KM3NeT /ORCA LBNF/DUNE JUNO PINGU INO RENO-50
31 New research in Kamioka: - Gravitational waves
32 Researches in Kamioka (2017) In 1983, we had only 1 experiment (Kamiokande) The map of underground Kamioka in 2017 is shown right. Probably, this development is due to the dynamics of KAGRA science. In any case, we have started a new project on gravitational waves in 2010.
33 Gravitational waves A. Einstein predicted gravitational waves in 1916 base on his theory of general relativity.
Black hole
Black hole
Image of the gravitational wave emission from a binary black hole system. These back holes merge and a new heavier black hole will be created.
34 The first detection of gravitational waves in LIGO (Sep.14, 2015)
Red Blue
2 back holes with the masses of 36 Msun and 29 Msun merged at the distance of 1.3 B light-years. The mass of the newly formed blackhole was 62 Msun. GW energy of 3 Msun equivalent was emitted.
35 KAGRA and its unique features
The detector will be constructed underground Kamioka. Cryogenic mirrors will be used Reduction of seismic noise (to approximately 1/100). to reduce the thermal noise.
Very high sensitivity.
36 KAGRA under construction
One of the 3km vacuum tubes (Feb 2015) Polished cryogenic Central room (Nov. 2015) sapphire mirror (23kg). KAGRA had its initial operation in 2016, plans the first cryogenic interferometer operation in the spring of 2018, and the high sensitivity run in 2019. 37 International GW network
LIGO KAGRA
Virgo
IndIGO/LIGO-India
2LIGO+Virgo 2LIGO+Virgo+LIGO-India+KAGRA
S. Fairhurst, J. Phys. Conf. Ser. 484 (2014) 012007
38 Summary • “Kamioka” has been contributing a lot to basic science in the last 30 years, and expected to contribute more in the future. • In the early 1980’s, Kamiokande began to observe proton decays. • Kamiokade observed Supernova neutrinos and atmospheric neutrino deficit and confirmed solar neutrino deficit. These results gave strong motivation to construct Super-Kamiokande. • In 1998, Super-Kamiokande discovered atmospheric neutrino oscillations. • KamLAND contributed much to the understanding of solar neutrino oscillations. • KAGRA is a new project trying to observe gravitational wave signals. KAGRA would like to join the global GW network in a few years. • India is expected to play very important roles in basic science such as the neutrino and gravitational wave researches.
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