Nuclear Physics: Exploring the Heart of Matter (2013)

4

Global Nuclear Science

The G-20 nations—Argentina, Australia, Brazil, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Mexico, Russia, Saudi Arabia, South Africa, South Korea, Turkey, the United Kingdom, and the United States, plus the European Union—include countries with advanced economies and countries with emerging economies that are working together toward worldwide financial stability and the achievement of sustainable growth and development. As is generally recognized in the G-20 member nations, a crucial component for creating an innovative economic environment is a commitment to invest in research and education. This commitment is coupled with appropriate national policies in science and technology to attract the brightest minds and allow them to create new technologies to benefit society. Through the development of research facilities, the United States has enjoyed global leadership and dominance in many of the basic sciences. With increasing demands on resources from large science projects, a strategy has begun to emerge where members of the G-20 collaborate on the construction and operation of some of the largest projects. Examples of this include the ITER fusion reactor project and the Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN).

Today, most of the G-20 member nations support active programs in nuclear science. Other countries, especially those in the European Union, also support both facilities and programs in nuclear science. Below is a brief description of some of the major nuclear science programs and research facilities found in these countries. Table 4.1 provides information about the major facilities in the United States and Table 4.2 provides similar information about facilities abroad. The report is not

Table 4.1 Domestic Nuclear Physics Facilities

SOURCE: Information contained herein is based on the IUPAP Worldwide Overview of Research Facilities in Nuclear Physics, Booklet 41, available online at http://www.triumf.info/hosted/iupap/icnp/Report41-final-12-07-11.pdf. Except for MSU NSCL, the number of users per year is from the Summary Table, page xxix. The number of users per year for MSU NSCL is taken from the body of Booklet 41, given that the figure in the Summary Table is significantly lower than that listed in the body of the booklet.

Table 4.2 International Nuclear Physics Research Facilities

SOURCE: Information contained herein is based on the IUPAP Worldwide Overview of Research Facilities in Nuclear Physics, Booklet 41, available online at http://www.triumf.info/hosted/iupap/icnp/Report41-final-12-07-11.pdf.

intended to be inclusive. A detailed description of the world’s facilities has been assembled by Working Group 9 of the International Union of Pure and Applied Physics (IUPAP) and can be found at http://www.triumf.info/hosted/iupap/icnp/Report41-0317.pdf.

UNITED STATES

The U.S. Department of Energy (DOE) supports three nuclear science user facilities—the Argonne Tandem Linac Accelerator System (ATLAS) at Argonne National Laboratory (ANL), the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Accelerator Facility (JLAB), and the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL)—and the National Science Foundation (NSF) supports one—the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). The program at ATLAS is centered around particle beams from a superconducting linear accelerator that produces light and heavy ion beams to energies of around 15 A MeV. It is presently undergoing an upgrade to add accelerated fission fragments from a 1-curie californium source. The NSCL is a coupled superconducting cyclotron facility that produces heavy ion beams up to 200 A MeV that are used to produce rare isotope beams by fragmentation. These three facilities form the core of the experimental program in nuclear structure and nuclear astrophysics for the United States. Five smaller facilities that also focus on nuclear structure and astrophysics—three supported by DOE and two by NSF—are located at universities and one local DOE facility is supported at the Lawrence Berkeley National Laboratory (LBNL). The university facilities are at Florida State University, Notre Dame University, Texas A&M University, and the Triangle Universities Nuclear Laboratory. Also the NSF supports a physics frontier center—the Joint Institute for Nuclear Astrophysics (JINA)—as a consortium of three universities (Michigan State University, Notre Dame University, and the University of Chicago). The CEBAF facility features a continuous beam electron accelerator with energies up to 6 GeV and both polarized and unpolarized electron beams. The RHIC facility has two synchrotons used to produce counter rotating beams of heavy ions up to 100 A GeV and protons up to 250 GeV. At present, the beams undergo collisions at two different interaction points that are instrumented with the STAR and PHENIX detector systems. Table 4.1 summarizes the capabilities of the principal nuclear physics research facilities in the United States.

Each of the U.S. facilities has forefront research programs in nuclear science and all of them make significant contributions to the field. Both CEBAF and RHIC, which support user groups from many countries around the world, have made surprising scientific advances over the past decade. The recent discovery at RHIC from Au-Au collisions of a near perfect liquid form of hot matter has led to

significant advances in the study of matter at high energy density. Using polarized proton beams, a program with strong support from Japan, RHIC has also provided data that put significant constraints on the contribution of gluons to the spin of the proton. The effort at RHIC for the coming decade will be dedicated to utilizing the upgrade luminosity to understand the quantum rules that govern the newly discovered form of matter and the proton spin. At CEBAF researchers are mapping, with high precision, the internal structure of the nucleon, and they are carrying out precision tests of the electroweak Standard Model. With the upgraded facility, researchers will extend the mapping of the nucleon internal structure and look for exotic particles that are predicted by quantum chromodynamics (QCD). The NSCL and ATLAS programs have large user communities in the United States and from abroad. As is pointed out in Chapter 2, both facilities have made significant discoveries in the past decade.

In low-energy nuclear physics the domestic stable and rare isotope beam facilities have enabled U.S. nuclear scientists to be among the leaders in advancing the field to further understand the emergence of order and collectivity from the chaotic assembly of protons and neutrons forming nuclei, and to determine how nature has accomplished the assembly of a wide range of different nuclides through chemical evolution. A particularly exciting direction that has emerged in this area is the study of unstable rare isotopes. As noted below, many countries around the world have made or are making significant investments in this area to provide accelerators to produce rare isotope beams. These rare isotopes open a new window on nuclear structure and have suggested that the concepts and paradigms developed from data with stable nuclei are often only a projection of a more general theory onto a small subset of nuclei whose only distinction is that they were the first to be studied. Studies focusing on all nuclei will lead to a more comprehensive theory of the nucleus. A next-generation rare isotope beam facility for the United States, FRIB, is now under construction at Michigan State University that will provide unprecedented access to a wide range of nuclei very far from stability (see Figure 2.3).

U.S. nuclear scientists have played a major role in developing neutrino physics into an important research thrust for nuclear and particle physics. In experiments dating back to the 1960s, nuclear scientists found that the number of neutrinos expected from the nuclear reactions taking place in the sun was significantly greater than what was observed. This long-unresolved solar neutrino puzzle was clarified with the discovery of neutrino oscillations, and the subsequent work that has shown just how complex the neutrino sector is. To date, neutrinos provide the only definitive indication of new physics beyond the Standard Model. Further study of neutrino properties, and neutrinos as cosmic messengers, could have transformative research results. U.S. nuclear scientists play active roles in many major efforts in neutrino physics, including experiments to determine the neutrino mass scale,

to measure neutrinoless double-beta decay, to determine the precise mixing of neutrinos, and to study low-energy solar neutrinos.

Research in theoretical nuclear physics provides leadership and guidance to the experimental facilities, as well as supporting the existing experiments. Moreover, efforts are aimed at fundamental problems such as obtaining numerically exact solutions to the nuclear many-body problem, understanding the connection between QCD and nuclear physics, and predicting the existence of new phenomena. This research, which takes place on the international stage, offers opportunities for international collaboration between U.S. and foreign groups. In the United States, theory groups at the national laboratories and at universities work on a wide range of topics that cover the forefront areas of research in the field. The Institute for Nuclear Theory (INT) at the University of Washington serves as a national center for theoretical nuclear science research. Part of the INT program is to support workshops that bring together experimental and theoretical nuclear scientists from around the world to focus on important research topics. These workshops often have a major impact on both theoretical and experimental developments in the United States and other countries.

EUROPE

The European Strategy Forum on Research Infrastructures list of future European large research infrastructures identifies two new facilities in the field of nuclear and hadron physics—the Facility for Antiproton and Ion Research (FAIR) to be built at the site of the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany, and SPIRAL2 at the Grand Accélérateur National d’Ions Lourds (GANIL) site in Caen, France. Both facilities have recently been funded and will spearhead research in fundamental and applied nuclear sciences in Europe after the completion of their first construction phases, which are expected to occur in 2016 and 2014, respectively. These facilities are complemented by a world-competitive experimental program in heavy-ion, radioactive ion-beam, and antiproton research at CERN and by a suite of national accelerator laboratories for lepton and hadron physics.

Europe supports several international centers for nuclear theory. The European Center for Theoretical Studies in Nuclear Theory and Related Areas (ECT*) in Trento, Italy, is focused on development of new theoretical approaches and connections of nuclear physics with astrophysics, elementary particle physics, and atomic physics. It hosts numerous workshops and research collaboration meetings, with good representation from the United States. Although it does not have a permanent faculty, it runs an annual doctoral training program for graduate students on a different specialized topic in nuclear theory each year, and has a strong postdoctoral research program.

The Helmholtz Alliance EMMI (Extreme Matter) Institute, a collaboration between 13 German and international partners, including the United States, has a strong theoretical effort in QCD, nuclear structure and reactions, and astrophysics, in particular exploiting interdisciplinary research such as strongly correlated systems.

The Jülich Supercomputing Centre (JSC) at the Forschungszentrum Jülich, with a number of supercomputers including the 1 Pflop JUGENE machine, is the principal European center for large-scale lattice QCD calculations in hadron physics and effective field theory calculations for nuclear structure. Large-scale astrophysical simulations are carried out at the Max Planck Institute for Astrophysics in Munich.

FAIR and GSI

FAIR will be the next-generation facility for fundamental and applied research with antiproton and ion beams. It will provide world-unique accelerator and experimental facilities, allowing for a great variety of unprecedented forefront research efforts in physics and applied sciences. FAIR is an international project with 16 partner countries and more than 2,500 scientists and engineers involved in the planning and construction of the accelerators and associated experiments. FAIR will be realized stepwise. The Modularized Start Version will include a Heavy-Ion Synchrotron SIS100, an antiproton facility, and a Superconducting Fragment Separator and will contain experimental areas and novel detectors for atomic, hadron, heavy-ion, nuclear, and plasma physics, and applications in material sciences and biophysics. It is expected to be operational late in the decade. Completion of FAIR, including the synchrotron SIS300, is envisioned to follow thereafter. The existing GSI accelerator system, consisting of the UNILAC linear accelerator and the SIS18 synchrotron, will be used as the injectors to the FAIR accelerator complex. The GSI experimental storage ring ESR is planned to be available for experiments until construction of the new storage ring NESR begins after the completion of the Modularized Start Version.

FAIR research focuses on the structure and evolution of matter on both a microscopic and a cosmic scale, bringing our universe into one laboratory. In particular, FAIR will expand the knowledge in various scientific fields beyond current frontiers, addressing the following:

• The properties of the strong (nuclear) force and its roles in shaping the basic building blocks of the visible world around us and in the evolution of the universe;

• Tests of symmetries and predictions of the Standard Model, as well as the search for physics beyond it in the electroweak sector and in the domain of the strong interaction;
• The properties of matter under extreme conditions, at both the subatomic and the macroscopic scale of matter; and
• Applications of high-intensity, high-quality ion and antiproton beams in research areas that provide the basis for, or directly address, issues of applied sciences and technology.¹

Compared to the existing GSI facilities, FAIR will provide an increase in beam intensities by factors of 100 to 10,000 and in beam energies by factors of 15-20. Moreover, the use of beam cooling techniques will enable the production of antiproton and ion beams of the highest quality—that is, with very precise energy and extremely small emittance. Upon completion, the FAIR accelerator complex can support up to five experimental programs simultaneously with beams of different ion species in parallel operation. This unique feature is made possible by an optimal balance in the use of accumulator, collector, and experimental storage rings.

The scientific user community of FAIR has organized itself into large international collaborations. The Compressed Baryonic Matter (CBM) collaboration will explore the phase diagram of hadronic matter by ultrarelativistic heavy-ion collisions; the Nuclear Structure, Astrophysics and Reactions (NuSTAR) collaboration will study the properties of exotic nuclei exploiting the unprecedented radioactive ion-beam capabilities of FAIR; and the antiProton ANnihilation at Darmstadt (PANDA) collaboration will use p-p collisions to explore the role of QCD in hadron structure and dynamics. Beyond nuclear physics, the Atomic, Plasma Physics and Applications (APPA) collaboration will perform forefront research in atomic and plasma physics as well as in applied sciences like material research and in medical and biophysics.

FAIR builds on the existing infrastructure and experience at GSI. Research at the existing GSI accelerator complex will continue until FAIR becomes operational. Recent experimental highlights at GSI include the discovery of the heaviest elements from Z = 107-112 and the development of carbon beams to be used for radiation therapy in treating cancer.

GANIL and SPIRAL2

GANIL in Caen, France, is an accelerator complex delivering both stable heavy-ion beams ranging from carbon to uranium and radioactive beams produced either

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¹ Portions of this paragraph were adapted from C. Sturm, B. Sharkov, and H. Stöcker, 2010, 1,2,3 … FAIR!, Nuclear Physics A 834:682c.

in flight or with the Isotope Separation Online (ISOL) method in the Système de Production d’Ions Radioactifs Accélérés en Ligne (SPIRAL) facility. GANIL hosts a large suite of state-of-the-art detector systems to carry out a broad scientific program that focuses on properties of exotic nuclei and research in atomic physics, material sciences, and radiobiology.

The main scientific goal at SPIRAL2 is the exploitation of very intense radioactive ion beams to explore the properties of nuclides far from stability and to extend the knowledge of nuclear structure toward presently unexplored regions of the nuclear chart. SPIRAL2 will be an international facility. Already several memoranda of understanding with major laboratories, institutions, and ministries worldwide have been signed.

The driver of the SPIRAL2 facility is a high-power, continuous-wave superconducting linear accelerator (linac). It will accelerate a deuteron beam to produce neutrons that interact with a uranium target to produce radioactive ions by neutron-induced fission. The facility will yield radioactive ion beams in the mass range A = 60 to 140, with intensities that will be unique in the world for some species. These beams will be available at energies ranging from a few keV/A at the new experimental hall for low-energy exotic nuclei up to 20 A MeV at the existing GANIL experimental areas, where a suite of next-generation detectors will be used to detect gamma-rays, charged particles, and neutrons.

The SPIRAL2 linac will also accelerate high-intensity heavy-ion beams up to 14.5 A MeV. These heavy ion beams will be used to produce neutron-deficient nuclei by the Isotope Separation On-Line (ISOL) method or very heavy nuclei by fusion evaporation. Another option, to produce very heavy or neutron-deficient nuclei, will exploit the in-flight method with the Super Separator Spectrometer (S³). The high neutron flux produced with the deuteron beams at the new Neutron for Science Facility (NFS) will provide additional experimental opportunities for applied research.

The timeline of SPIRAL2 anticipates commissioning of the linear accelerator, the S³ spectrometer, and the NFS experimental hall in 2012, with the commissioning of radioactive ion-beam production and the DESIR low-energy facility to follow in 2014. In the future, GANIL plans to increase the intensity of medium- and heavymass radioactive ion beams by adding a second heavy-ion injector. The SPIRAL2 project is seen as an important step towards EURISOL, a large-scale ISOL facility for Europe, for which a conceptual design study has been carried out within the fifth framework program of the European Union.

CERN

A Large Ion Collider Experiment (ALICE) is the largest nuclear physics experiment in the world. It exploits the physics potential of nucleus-nucleus collisions

at the multi-TeV energy scale offered by the LHC at CERN. To reach this goal, the ALICE Collaboration of more than 1,000 members from 116 institutions in 33 countries has built a multipurpose heavy-ion detector.

The physics motivation is to study strongly interacting matter at extreme energy densities, and the quark gluon plasma in particular. This new phase of matter and its properties are key issues in QCD for understanding the fundamental phenomena of quark confinement and chiral-symmetry restoration. For this purpose, a comprehensive study of the hadrons, electrons, muons, and photons produced in the heavy-ion collisions is required, which can be achieved by various dedicated components of the ALICE detector. The experiment started operation in 2010 with proton-proton collisions. A first successful heavy-ion run with Pb-Pb collisions was performed at the end of 2010.

The full experimental program of ALICE will take place over more than a decade and will benefit from the successive upgrade of the beam energies available at the LHC. For the mid-term, an ambitious upgrade of the detector is envisioned, which will include a new inner tracker to extend the Cherenkov and calorimeter coverage and to increase the rate capability for physics with rare probes and the construction of a new tracking calorimeter system that will operate at forward angles relative to the beam direction.

Other LHC collaborations have significant efforts aimed at searching for new physics in both p-p and Pb-Pb scattering. Two of these—ATLAS and the Compact Muon Solenoid (CMS) experiment—have significant participation from the U.S. relativistic heavy-ion physics community. The primary goals of the heavy-ion programs for ATLAS and CMS are similar to those for the ALICE collaboration. Each collaboration uses the physics variables that their detector is optimized to measure to study the physics in these ultra-high-energy heavy-ion collisions.

The Isotope Separator Online Detector (ISOLDE) is primarily a nuclear physics facility at CERN that produces radioactive beams through fission, spallation, and fragmentation reactions induced by 1.4-GeV protons from the CERN Proton Synchrotron Booster for research in nuclear structure, nuclear astrophysics, and fundamental physics. With several decades of accumulated experience in target and ion-source knowledge, ISOLDE has extracted and separated about 700 different isotopes of more than 70 elements, which is by far the largest number of isotopes to be available for users at any ISOL facility in the world. With the installation of the postaccelerator REX-ISOLDE, it is now possible to accelerate radioactive isotopes up to mass number 238 to energies of 3 A MeV. This energy will be increased to 10 A MeV through the HIE-ISOLDE (High Intensity and Energy) project. Additionally, the project will improve beam quality and intensity. These goals will be achieved by replacing the REX linac by superconducting cavities and by the higher intensity primary beams provided by the new CERN injector LINAC4. HIE-ISOLDE has

been approved by the CERN Research Board and is scheduled to be available to users around 2014.

For the last decade the Antiproton Decelerator (AD) at CERN has been providing low-energy antiprotons for experiments to produce and study cold antihydrogen atoms, to investigate the spectroscopy of antiprotonic helium, and to study the biological effects of antiprotons on living tissue. The physics motivations for these experiments are tests for charge conjugation-parity-time symmetry (CPT) and the determination of fundamental constants like the electron to antiproton mass ratio and the antiproton magnetic moment. In the future an approved experiment, the Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy (AEGIS), aims at measuring the gravitational coupling of matter and antimatter.

The approved experimental program at the AD extends to 2016. As an addition to the AD, a further deceleration stage, the Extra Low Energy Antiproton Ring (ELENA) project, is currently under discussion. The ELENA project would bring antiprotons to the keV energy range and would bridge the gap until the Facility for Low-Energy Antiproton and Ion Research (FLAIR) project at FAIR, which is not part of the Modularized Start Version, becomes available.

Other European Facilities

The physics community in Europe also operates a host of smaller hadron and lepton accelerator facilities. These laboratories run focused programs in which they are quite competitive on the international scale, and all of them have significant theory groups.

The hadron beam facilities include the two national laboratories in Italy, at Legnaro and Catania, the Accelerator Laboratory at the University of Jyväskylä in Finland, the Kernfysisch Versneller Instituut (KVI) at Groningen in The Netherlands, the cooler synchrotron (COSY) facility at the Forschungszentrum Jülich in Germany, the Linear Accelerator Near the Tandem of Orsay (ALTO) facility in Orsay, France, and the facilities at the Joint Institute for Nuclear Research in Dubna, Russia. Besides performing dedicated research in nuclear science and its applications, these facilities and a suite of smaller laboratories, often located at universities, play an important role in educating the next generation of nuclear scientists and in the development and testing of devices to be used at the large-scale facilities.

The lepton beam facilities include the Microtron Accelerator for X-rays (MAX) IV Laboratory (MAX-lab) in Lund, Sweden; the two electron accelerators, Mainz Microtron (MAMI) at the Johannes Gutenberg University of Mainz and Electron Stretcher and Accelerator (ELSA) at the University of Bonn, in Germany; the high-energy physics experiment Common Muon Proton Apparatus for Structure and Spectroscopy (COMPASS) at the Super Proton Synchroton at CERN; the Frascati National Laboratory in Italy with its e⁺e⁻ meson facility, Daphne; and the

e⁺e⁻ VEPP facility at the Budker Institute of Physics in Novosibirsk, Russia. Finally, the Technische Universität Darmstadt operates a superconducting low-energy electron accelerator, the superconducting Darmstadt electron linear accelerator (S-DALINAC).

Many of these hadron and lepton beam facilities are considering dedicated upgrade programs. These as well as detailed descriptions of the facilities and their physics goals and achievements can be found in the report Perspectives of Nuclear Physics in Europe, published by the Nuclear Physics European Collaboration Committee (NuPECC) in December 2010.²

The Extreme Light Infrastructure (ELI-NP) is a proposed high-energy laser research facility of the European Union to be constructed by 2016 in Bucharest, Romania. Based on a linear electron accelerator, the Doppler shift of Compton-backscattered laser photons off relativistic electrons is used to generate a high-energy gamma-ray beam for basic research in nuclear structure and applications. The average photon flux at ELI-NP is envisaged to be similar to that of the next-generation laser Compton backscattering facility, the mono-energetic gamma ray facility (MEGa-Ray) at Lawrence Livermore National Laboratory (LLNL) (operations planned for 2013), and will exceed the flux at existing facilities by several orders of magnitude.

Europe has had a long tradition in underground science with the development in the 1980s of the Gran Sasso facility. It is still the largest underground laboratory in the world and houses detectors carrying out a wide range of fundamental studies. It also has served as the home for the Laboratory for Underground Nuclear Physics (LUNA) facility, which has a low-energy underground accelerator and detector setup to measure nuclear reactions of astrophysical importance. The facility is limited in reach by the accelerator and cannot access reactions such as the very important alpha-induced reactions.

ASIA, AFRICA, AND AUSTRALIA

Over the past decade, China and Japan have made major investments in new nuclear physics facilities, which have led to a substantial growth of the field in those countries. The buildup of nuclear physics capabilities in Asia appears to be continuing into the future with rapid growth of funding in India and for a major new nuclear physics facility to be built in South Korea. Groups from China, India, and Japan have been playing major roles in the two large collaborations at RHIC. Many of them also are involved in the heavy-ion program at the LHC. Groups

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² European Science Foundation, 2010, Perspectives of Nuclear Physics in Europe-NuPECC Long Range Plan 2010. Available online at http://www.nupecc.org/pub/lrp10/lrp2010_final_hires.pdf; last accessed on October 27, 2011.

from Japan also have been carrying out experiments that focus on hyperon physics at JLAB. For many years, U.S. nuclear physicists have worked with Japanese colleagues on neutrino experiments at Kamioka. Recently, a new reactor neutrino experiment began in China that includes nuclear and high-energy physicists from the United States.

The two main streams of nuclear theory research in Japan continue the Japanese tradition of excellence in many-body theory. The first area, the many-body physics of quarks and gluons, is very strong and growing as a consequence of experimental programs at RHIC and the Japan Proton Accelerator Research Complex (J-PARC). The RIKEN-BNL Research Center (RBRC) headquartered at BNL, has been training young scientists from the United States and Japan who are now leaders in the field. The second area, the many-body physics of hadronic systems (nucleons and hyperons), is now regaining interest after losing young people to QCD studies, in part owing to the Radioactive Ion Beam Facility (RIBF) at RIKEN, near Tokyo. The focus has been on first-principles calculations, including massive lattice QCD and ab initio many-body calculations. A significant factor in this work has been the very strong lattice QCD group at the University of Tsukuba, which has stimulated interest and abilities in this area.

Japan has completed construction of two large-scale projects for nuclear physics during this decade. RIBF is now providing particle beams from hydrogen to uranium at up to 350 A MeV. Through extensive work on beam development, beam intensities for some light-ion beams have now reached the design goal. During the first several years of operations, intensities of the heaviest beams have been limited by the lifetime of stripper foils. A gas stripper system, which has been developed for the facility and should be operational by 2012, will allow for significant increases in the intensity of heavy beams. Even at the present level of operation, RIBF has the highest intensities in the world for very neutron-rich secondary beams.

J-PARC, a large new facility near Tokai, Japan, has been built to accommodate a very broad physics program ranging from neutron scattering for materials science to high-energy neutrino-scattering experiments. The accelerator complex includes a high-beam power linac followed by a 3-GeV synchrotron, which is designed to deliver up to 1 MW of protons, and a 50-GeV synchrotron, which is designed for a proton beam power of 0.75 MW. Ground breaking for the facility was in 2002 and commissioning of the linac began in 2006. The first neutrino beam from the 50-GeV synchrotron to the neutrino detector at Kamioka occurred in 2009. Secondary beams of muons, pions, kaons, and antiprotons will be used to carry out a broad hadronic and fundamental symmetries physics program. Commissioning of the first phase of the hadron physics experimental area began in late 2009 and will continue as spectrometers and beam lines are completed. The beam power at J-PARC is projected to increase from present values of about 200 kW and reach design goals by late 2013. Recently the theory center at the High Energy Accelerator

Research Organization (KEK) in Japan at the request of the Japanese Nuclear Theory Association, appointed five university nuclear theorists as visiting scientists to help organize J-PARC theoretical activities. The massive Tohoku earthquake that struck Japan on March 11, 2011, caused considerable damage to the J-PARC facility. However, most of the damage was limited to the surface infrastructure; fortunately, the accelerator components suffered only moderate damage. Following an assessment of the facility, repairs were carried out to have the facility back on line for beam tests in the first quarter of 2012. This unfortunate event will probably impact the facility’s plan to reach the full design intensity by late 2013.

In addition to the two international facilities for nuclear physics in Japan, several smaller facilities continue to operate. Among the largest of these is the Research Center for Nuclear Physics (RCNP) in Osaka. The facility is built around an azimuthally varying field (AVF) and a Ring cyclotron. These accelerators provide stable light-ion beams from H up to ions with A < 20. The traditional focus of the program has been on high-resolution studies of spin and isospin degrees of freedom. As a national research center RCNP is primarily used by Japanese experimentalists. Typically about 15 percent of the users come from outside the country.

Supercomputing in Japan provides considerable support to the nuclear theory effort, well beyond that available in the United States. The national 10 Pflop (from 2012) supercomputer KEI, at the Advanced Institute for Computational Science in Kobe, is one of the five “urgent major projects” in science and technology; it supports a unique collaboration among nuclear, particle, and astrophysics scientists and is supporting a growing number of theory positions. Formidable supercomputing power is available to nuclear physics through the KEK supercomputers, with over 1 Pflop; the Center for Computation Sciences at the University of Tsukuba, with 95 Tflop; and the Yukawa Institute for Theoretical Physics (YITP) at the University of Kyoto, with 91 Tflop. In addition to nuclear theory efforts, Japan supports a growing theory collaboration among string theorists, condensed matter theorists, and nuclear theorists (who play a joining role among these disparate fields) that is centered on the physics of strongly coupled many-body systems.

Japan supports two important programs with the United States in nuclear theory: the RBRC, with its focus on QCD, and the Japan-U.S. Theory Institute for Physics with Exotic Nuclei (JUSTIPEN) at RIKEN, which focuses on the physics of rare isotope beams. These two programs have been very successful in developing collaborations between theorists in the two countries. Following on the success of JUSTIPEN, a new initiative has been launched—the French-U.S. Theory Institute for Physics with Exotic Nuclei (FUSTIPEN). Like its counterpart, the program at FUSTIPEN also will focus on physics with rare isotope beams. Recently a new Japan-U.S. Institute for Physics with Exotic Nuclei (JUSEIPEN) was set up to promote experimental activities by U.S. participants at the RIKEN facility RIBF.

China is promoting nuclear physics research through investments at facilities

in Lanzhou and Beijing. At Lanzhou, a separated sector cyclotron is used to provide beams for acceleration and storage in a synchrotron ring that can accelerate heavy ion beams up to 1 A GeV for carbon-12 and 500 A MeV for uranium-238. Primary beams from the synchrotron can be used for experiments. They also are used to produce radioactive beams through fragmentation that can be collected in a second storage ring at the end of a fragment separator beam line, where they are cooled and accelerated. Both storage rings are equipped with internal target stations. Commissioning of the main storage ring began in 2005 and was followed by commissioning of the second storage ring. The facility is now in operation and carrying out experiments. It is used primarily by scientists in China.

The Beijing rare ion beam facility, BRIF, is an upgrade of the existing nuclear physics laboratory at the Atomic Energy Commission in Beijing. The central part of the upgrade is the construction of a high-current 100 MeV compact proton cyclotron. The proton beam will be used to produce secondary radioactive beams by the ISOL technique, which will be accelerated in the existing tandem accelerator. A superconducting linac will be added after the tandem for further beam acceleration. Design and construction of the cyclotron began in 2006. Civil construction for building modifications is scheduled to begin in late 2010. The ISOL system and the superconducting linac designs have been completed and construction is now under way. Like the facility at Lanzhou, BRIF will be used primarily by researchers in China.

Experiments at the new facilities in China drive theoretical research that focuses on nuclear reactions, nucleosynthesis, nucleon-nucleon interactions, QCD matter in heavy ion collisions, and hadronic physics. Work is driven in part by experimentation at newer facilities in China, such as the Cooling Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFL-CSR), the Beijing Spectrometer III (BES-III) at the Beijing Electron Position Collider II (BEPCII), and the Shanghai Synchrotron Radiation Facility (SSRF).

Rather recently, China built an underground laboratory to carry out a broad research program in fundamental physics at Jinping. The facility is built under a large mountain and has a tunnel for drive-in access. When completed, it will have about the same space for experiments as the Gran Sasso facility in Europe but at twice the depth.

Today, the nuclear theory effort in China is considerably smaller than the one in Japan, with most of the nuclear theorists at the Institute of Nuclear Science, the Institute of High-Energy Physics of the Chinese Academy of Sciences, the Center for Theoretical Physics, Peking University, and Tsinghua University, all in Beijing, as well as Huazhong Normal University in Wuhan and Fudan University in Shanghai. The rapid growth of Chinese university research and ever-increasing contact with foreign research—including support of active theory collaborations with theorists in the United States, Germany, and Japan, and experimentalists at major foreign

laboratories, e.g., JLab and RHIC in the United States, LHC and GSI in Europe, and RIKEN in Japan—provides a framework for an expanded program in nuclear theory in China.

As part of the effort to grow its program in nuclear physics, China has created a significant number of new faculty positions at its major research universities. The universities are aggressively recruiting faculty who were originally from China but have been trained and employed in the United States and Europe. This enhances the Chinese research program at the expense of other efforts such as the U.S. effort.

India has started making a significant investment in nuclear physics, which is driven in part by the anticipated growth in the use of nuclear power for the region. As part of this effort, the laboratory at Kolkata is undergoing an upgrade to radioactive beams. Two different approaches are being developed to produce secondary beams. One approach uses beams from the K130 cyclotron on a thick target with an ISOL type system. The other approach uses photon-induced fission on uranium. A 50-MeV high-power electron linac is being built in cooperation with TRIUMF to produce the photons for fission. After separation, relatively low-energy radioactive ion beams (RIBs) will be produced by acceleration through a room-temperature linac. Other nuclear physics laboratories in India are carrying out infrastructure improvements and developing new detector technologies. Beyond the nuclear physics laboratories, India has also begun developing a deep underground laboratory for neutrino studies (INO).

In a very recent development, South Korea is planning to construct a major new international rare isotope accelerator facility for nuclear physics, KoRia, which will be part of a new Basic Science Institute (BSI) to be built in the country. Legislation authorizing the construction of a new city, the home of the BSI, has now been passed in South Korea. Planning for the nuclear physics facility has been under way for about a year. The concept that is being developed includes a 70-kW beam of protons up to 100 MeV that will be used for ISOL production of secondary particles. A superconducting linac will accelerate the ISOL beams to typical energies of about 15 A MeV for reaction studies. A second superconducting linac will be added to the facility to boost ion beams to about 200 A MeV for uranium. The higher energy linac will be built to accelerate both RIBs from the first part of the facility and high-intensity stable beams from a superconducting linac injector. Following the high energy linac, a fragmentation beam line will be set up to collect radioactive ions produced either from the accelerated RIBs or stable beams. As part of the project, spectrometers are being designed to use both the 15 A MeV RIBs and the RIBS produced either by fragmentation or direct acceleration at high energies. The laboratory being developed will serve as a catalyst to increase the nuclear physics workforce in South Korea and it also will be developed as an international user facility.

Korea presently supports several cooperative national research efforts, e.g.,

between the World Class University (WCU) project at Hanyang University in Seoul and the Asian Pacific Center for Theoretical Physics (APCTP) at Postech in Pohang. The focus here is to develop theoretical study and awareness of interdisciplinary problems between particle, hadronic, and nuclear physics, together with astrophysics and condensed matter, with connections to future experiments at FAIR, J-PARC, and rare isotope accelerators, as well neutron stars. Also supported is the multiinstitutional heavy ion meeting (HIM) effort in heavy ion physics. International collaborations in nuclear theory include that of the APCTP with a number of international centers, WCU with the Yukawa Institute for Theoretical Physics in Kyoto, and HIM with theorists at CERN, GSI, and RHIC.

In Africa, the major research facility for nuclear science is the iThemba laboratory in South Africa. A separated sector cyclotron operated at the laboratory near Capetown is used for isotope production and for research in nuclear science. Beyond this, several other countries operate small research facilities that are used in part for nuclear science.

Accelerator-based nuclear physics research in Australia is centered at the Australian National University in Canberra, Australia. The science program is built around a Pelletron electrostatic accelerator and a superconducting linac that together provide a wide variety of particle beams. An upgrade project began in 2009 to improve the system reliability and to develop the capability to produce radioactive ion beams.

CANADA AND LATIN AMERICA

Nuclear science in Canada has a rich history that dates from Rutherford’s early work at McGill University. Today it is centered at the TRIUMF laboratory in Vancouver, Canada. Over the last decade, TRIUMF has developed an ISOL-based program of radioactive beam production. The 500-MeV proton cyclotron serves as the driver for producing secondary beams. With a primary beam power of nearly 100 kW, TRIUMF has produced the highest intensities of many light ion beams in the world. A superconducting linac serves to accelerate the RIBs to energies of 10 A MeV for light species. TRIUMF and Canada have made a significant investment in ancillary equipment for studying isotopes (e.g., the ISAC-I and ISAC-II experimental halls and their associated detectors), making it one of the top RIB facilities in the world. Nuclear theory in Canada is supported at TRIUMF and at several universities throughout the country.

Building on its expertise in isotopes for nuclear physics, TRIUMF is also pursuing a program in nuclear medicine, using proton beams for treatment of ocular melanomas and studying the physics, chemistry, and biology of medical isotopes for diagnosis and treatment of cancer and neurodegenerative disease. Together with

commercial partner Nordion, Inc., the team produces about 2.5 million patient doses of medical isotopes every year that are exported around the world.

Canada has ambitions to further expand its programs in isotopes for physics and medicine. Funding was approved recently to develop the Advanced Rare Isotope Laboratory (ARIEL) at TRIUMF, a facility that will feature a 0.5-MW superconducting radio frequency electron linear accelerator and two additional isotope-production targets. ARIEL will employ photofission to complement the cyclotron’s proton-spallation technique; photofission promises access to neutron-rich isotopes at intensities beyond what are presently available. ARIEL will generate its first beams by 2015. In collaboration with a group from RCNP in Japan, TRIUMF plans to develop a source of ultracold neutrons and use it to carry out tests of fundamental symmetries such as a measurement of the neutron electric dipole moment.

Canada has been a world leader in underground science for many years. Following the successful completion of the solar neutrino experiment, SNO, at the Sudbury mine, Canada has been investing in expanding its underground program. The SnoLAB facility in Canada is now one of the deepest sites in the world. A broad research program has been established there, which will continue to make Canada an international leader in the field.

Nuclear science has a long tradition in Latin America, where research programs were initiated more than a half century ago. Today active research programs exist in most South American countries and Mexico, together with a large fraction of activities directed at important pressing problems where nuclear physics can contribute, including health, the environment, and energy. Argentina, Brazil, and Mexico have broader programs than other countries in the region, with operating facilities for basic research and educational programs that offer doctoral degrees in basic and applied nuclear physics. The research and educational activities in Venezuela, Colombia, Peru, and Chile are on smaller scales but are nonetheless significant within their respective country’s basic research portfolios.

Argentina’s nuclear physics research activities involve both basic research and applications. The National Atomic Energy Commission (CNEA), a government entity that maintains major research centers spread out throughout the country and that currently is in a very active expansion phase, plays a significant role. In Buenos Aires the major facility for research is the 20-MV Tandem (TANDAR), which has a basic research program centered on the investigation of nuclear reactions induced by beams of stable, weakly bound nuclei. The accelerator includes a Q2D magnetic spectrometer, a microbeam facility (beam spots of about 1 μ²) with high resolution X-ray detection, an external beam irradiation facility with online dose determination, and heavy-ion identification based on a time-of-flight facility. The other major CNEA centers are in Bariloche and Ezeiza, each with unique capabilities for basic and applied work. Universities also play important roles in

the use of CNEA facilities and in the development of and participation on other external activities like the Pierre Auger Observatory. Argentina has also developed strong programs in medical physics and nuclear engineering.

Nuclear physics research in Brazil and Mexico is conducted at a large number of universities with programs in basic research and applied nuclear physics. In both countries nuclear scientists also play significant roles in international collaborations (Auger, RHIC, LHC-CERN) and in the development and implementation of nuclear science applications for their own use. In Brazil one of the major investments is a new radioactive ion beam facility (RIBRAS) coupled to the 8-MV Pelletron Tandem at the University of Sao Paulo. RIBRAS is dedicated to basic research and to the training of nuclear scientists. In Mexico nuclear physics is at the core of activities in radiation physics, medical physics, and cosmic rays.

The existing political climate is presently favorable for developing collaborations in Latin America (MERCOSUR and other initiatives). Nuclear scientists in the region are helping to take advantage of this situation and join forces in projects of common interest. An example is the recent proposal for ANDES. The design and development of ANDESlab, an underground laboratory in Argentina, is a joint South American effort between Argentina, Brazil, and Chile. The ANDESlab is foreseen as a complete underground laboratory to enable the measurements of neutrinoless double-beta decay, neutrino oscillations, and nuclear reactions of importance to stellar evolution. Table 4.2 summarizes the capabilities of the principal nuclear physics research facilities outside the United States.

U.S. NUCLEAR SCIENCE LEADERSHIP IN THE G-20

Large investments in new facilities for nuclear science have been made over the last decade by G-20 member nations and more are planned in this coming decade. While it is difficult to get a cost for these facilities, a conservative estimate is that over $4 billion will be spent by other G-20 nations before 2020. U.S. researchers are taking advantage of this by establishing research collaborations with local groups at the new and upgraded facilities. But if the United States is to remain a global leader in nuclear science, it must proceed with the plans that it has developed for its own new and upgraded facilities.

Through the long-range planning process of the Nuclear Science Advisory Committee (NSAC), a path forward for U.S. nuclear science has been laid out that would provide world-class facilities for research in several parts of the field well into the future. Over the past few decades, nuclear science around the world has evolved from a discipline where experiments were mostly carried out at local facilities to one that depends heavily on large national user facilities. During this time, the United States developed two major facilities, RHIC at BNL and CEBAF at JLAB.

Because the present energy capability of CEBAF limits the research program,

the facility is undergoing an energy upgrade from 6 to 12 GeV. With the upgraded facility, the United States is expected to lead this area of hadron physics research well into the next decade.

In ultrarelativistic heavy-ion physics, the United States will share leadership with the LHC at CERN, where for one month of each year the formation of matter at high energies and densities will be studied in Pb-Pb collisions with more than 20 times the collision energy and perhaps twice the temperature of collisions at RHIC. These experiments will yield the highest energy probes of quark-gluon plasma. U.S. scientists and students are significant partners in this European effort, building components and developing software for the ALICE, ATLAS, and CMS detectors to be used in these studies. Meanwhile at RHIC, detector and luminosity upgrades are proceeding that, together with the flexibility to vary collision systems and energies over a wide range, will give RHIC researchers many advantages in the systematic investigation of the properties of quark-gluon plasma in varied regimes.

A major research focus for nuclear science worldwide lies in the development of facilities to produce and study the exotic nuclei that nature makes during catastrophic events such as a supernova. The science motivating these studies is to understand the emergence of order or collectivity from chaos and the evolution of stars, which produce the elements and lead, ultimately, to the chemical evolutions that allow the development of life. The United States plans to build the Facility for Rare Isotope Beams (FRIB) at Michigan State University, which will be a world-leading facility in rare isotope science when it is completed in 2018. For many rare isotope beams, FRIB will provide the highest beam intensities available in the world. It also is expected to be the only facility that will provide low-energy reaccelerated beams produced via projectile fragmentation. Here, however, it will have major competition from other facilities around the world. Today, the United States holds a leading position in the development of tools and techniques to study nuclear astrophysics. The establishment of the physics frontier center, JINA, has assembled an exemplary combination of astronomers, astrophysicists, nuclear theorists, and nuclear experimentalists. Together, they are expected to more rapidly bring about an understanding of stellar evolution as well as the explosive cosmic events that contribute to the synthesis of matter. JINA has served as a model for the Helmholtz Foundation in Germany, which has developed several similar centers of excellence, and for the formation of a Brazilian center for nuclear astrophysics. India, China, and Argentina have sought assistance from experts at JINA as they develop accelerators to be deployed in underground laboratories.

While U.S. scientists were pioneers in the studies of neutrinos, some of the most definitive work to date has been done at underground laboratories in Japan and Canada, with United States participation. There is great interest worldwide in understanding neutrino properties and measuring neutrinoless double-beta decay, which has resulted in very rapid development of underground laboratories

at several locations around the world in a very short time. If the United States proceeds with plans to develop an underground science laboratory, it can become a world leader in this field. Fitting naturally into a new underground laboratory would be the U.S.-led Majorana experiment to measure neutrinoless double-beta decay and an accelerator laboratory for low-energy nuclear astrophysics, which would further unravel the details of stellar evolution.

Over the years, U.S. nuclear scientists have been innovative in exploiting opportunities to carry out experiments at facilities around the world. This effort should be commended and encouraged in the future. But without a significant U.S. investment in facilities throughout this decade, which includes the operation of existing facilities, the timely construction of new capabilities, and the flexibility to take advantage of new answers and discoveries, the United States could quickly lose its leadership in many of the forefront areas of physics research.