Contents and purpose of our research

Subjects of research at Nuclear Spectroscopy Group

Quantum theory and the theory of relativity brought explosive advances to physics in the 20th century. Their unification explained the symmetric existence of matter (particles) and antimatter (antiparticles). However the universe which we now inhabit contains only matter; the antimatter has disappeared. Why is this? Answering this question is one of the major goals of 21st century physics. The key is proving that it is possible for the worlds of particles and antiparticles to intersect. This laboratory is seeking an answer to this question through research concerning double beta decay. We have constructed a CANDLES detector system, and are conducting measurements at the Kamioka underground laboratory (Institute for Cosmic Ray Research, University of Tokyo). The issue of unknown matter in the universe is another large question, and we are also involved in the search for dark matter. In technical terms, the search for dark matter is closely related to our research into double beta decay.

Atomic nuclei are the building blocks that make up our world. Fundamentally, an atomic nucleus is composed of protons and neutrons. Research into their composite particles discovered large numbers of particles called hyperons, which are in the same family as protons and neutrons. Evidence that they are of the same family as protons and neutrons can be seen in the fact that they form atomic nuclei. These are hypernuclei. They can study by creating them in an accelerator. These atomic nuclei do not exist in the real world, however knowledge of them is necessary in order to explain neutron stars, which can be described as extremely dense atomic nuclei. It is also possible that a neutron star contains not just hyperons, but also kaons that are compressed into bosons – a possibility that has been suggested by our recent research. In Japan, experiments have started at the J-PARC accelerator, an accelerator with world top-class performance that was constructed in Tokaimura for this research. This laboratory is also conducting experiments to investigate neutron-excess hypernuclei.

Research

Use of non-accelerator experiments in an underground laboratory with a low radiation background to search for violation of lepton number conservation and generation of matter of the universe(the search for double beta decay) and to search for dark matters, and to conduct research into basic interactions and the laws of conservation.

Violation of lepton number conservation and generation of matter of the universe(the search for double beta decay)

http://wwwkm.phys.sci.osaka-u.ac.jp/info/syoukai/dm.html

The search for cosmic dark matter

http://wwwkm.phys.sci.osaka-u.ac.jp/info/syoukai/neumass.html

Research facilities

Oto Cosmo Observatory Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo

Interaction of a hypernucleus and strange (s) quarks inside the nucleus. Use of hypernuclear spectroscopes for kaon and pion nuclear spectroscopy. Investigation of hypernuclei formation and decay by (π, K) and (K, π) reactions in order to explain strong and weak interactions including s quarks.

Research facilities

J-PARC HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION, KEK Brookhaven National Lab.

Experiments to verify symmetry of various particle and nuclear phenomena. Experiments to verify generation of strange quarks by weak interaction. Research into quark and hadron nuclear physics in the 1 GeV/C region.

Research facilities

Research Center for Nuclear Physics (RCNP), Osaka University

Using laser electron photons (1 – 4 GeV) to explain the structure and reactions of hadron and quark systems which are based on quarks in atomic nuclei and nucleons (QCD).

Research facilities

SPring8

Research facilities

J-PARC (Japan Proton Accererator Research Complex)　
http://j-parc.jp/index-e.html

Brookhaven National Lab.
AGS accelerator and related facilities
https://www.bnl.gov/world/

HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION, KEK
Proton synchrotron and core experiment facilities
http://www.kek.jp/en/

Research Center for Nuclear Physics (RCNP), Osaka University
Accelerator and core experiment facilities
http://www.rcnp.osaka-u.ac.jp/

Ring Cyclotron
Accelerator and core experiment facilities
http://www.rcnp.osaka-u.ac.jp/Divisions/plan/yoran/ring-e.html

Oto Cosmo Observatory
Underground experiments using particle and nuclear spectroscopes (500 m below ground)
http://wwwkm.phys.sci.osaka-u.ac.jp/info/syoukai/oto-e.html

Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo
Underground experiments using particle and nuclear spectroscopes
http://www-sk.icrr.u-tokyo.ac.jp/index-e.html

SPring-8
Quark and lepton experiment facilities
http://www.spring8.or.jp/en/