C12. Commission on Nuclear Physics

Report to the Council and Commission Chair Meeting
Mexico
September 28-29, 2001

The meeting of the C12 commission occurred in 2001 at Berkeley during the International Nuclear Physics Conference. The meeting was well attended. The present status of nuclear physics and the highlights of the field were extensively reviewed.

At the request of the president of IUPAP, C12 has discussed nuclear energy in the context of global warming. The consensus of the commission is that nuclear energy has an important role to play in the production of world energy. Solutions exist for nuclear wastes. The problems are mostly societal issues.

Some Highlights from Nuclear Physics

The most exciting results are the recent observations from the Sudbury Neutrino Observatory in Canada. These results have solved the mystery of the missing solar neutrinos, a puzzle for solar theory for more than 30 Years. The results confirm that solar models are correct but give evidence that neutrinos decay and oscillate in their journey to the earth. Neutrinos transform from electron-neutrinos to muon- and/or tau-neutrinos. The flux of electron-neutrinos, measured in the charge current interaction Ve + d ® p + p + e-, together with the earlier results from Super-Kamiokande on the neutrino elastic scattering flux (encompassing all three neutrino types) ?x + e- ® ?x + e- show that there is a non-electron type active neutrino component in the solar flux. The total flux of active 8B neutrinos that can be so deduced is in excellent agreement with the predictions of solar models.

The quark gluon plasma is a state of matter that is predicted to have existed some 10 microseconds after the occurrence of the Big Bang. Seven different experiments at CERN, in which 33 TeV lead ions crashed into heavy element targets give strong hints of the existence of the quark gluon plasma. But confirmation of the existence of this new phase of matter is awaiting a new generation of results from the Relativistic-Heavy-Ion-Collider (RHIC) at Brookhaven and the future Large Hadron Collider at CERN. RHIC has now attained full energy with 100 GeV Gold ions colliding with 100 GeV Gold ions. The first experimental results were presented at INPC2001 in Berkeley.

Japan has decided to build a major 50 GeV and 1 MW multipurpose proton facility. Several beams will be available for particle and nuclear physics. Neutron physics and transmutation of nuclear wastes will be also important parts of the research program.

The discovery of the element 112 is confirmed. The domain of rare unstable nuclei is the focus of intense activity. Several new facilities will open a new research domain far from the stability line. The central question is to understand nucleon-nucleon interactions and the formation of nuclear matter in extreme situations. Major new facilities are proposed in Europe, Japan and the United States.

A wealth of data on the nucleon form factors have been obtained with new techniques with polarized electrons. High energy electron beams with both high intensity and high polarization (> 70 %) are now available for the first time.

Progress in thermonuclear fusion is considerable. The funding of the new ITER project is now being discussed between Europe, Japan and Russia.

Theory

A major development in nuclear theory is the considerable progress in lattice QCD that has been made recently and which is promised for the next few years. Developments in improved quark and gluon actions have increased to lattice spacing that one can use while still obtaining accurate continuum results. Funding agencies in Europe and the USA have agreed to support a number of dedicated High Performance Computers, all at the level of 10 Giga-flops or thereabouts. These machines should permit full QCD simulations at quark masses only a factor of 3 or 4 above the physical light quark masses. The combination of improved chiral extrapolation and the new generation of supercomputers means that we can look to lattice QCD producing accurate hadron properties at the physical quark masses within the next 3-5 years.

The three major centers of theoretical nuclear physics, ECT* (in Trento), INT (in Seattle) and CSSM (in Adelaide) continue to thrive and stimulate closer interaction between theorists around the world as well as between theorists and their experimental colleagues.