BUDKER INSTITUTE OF NUCLEAR PHYSICS

The Budker Institute of Nuclear Physics (BINP), located in Novosibirsk, Russia, was founded in 1958. It originated from Gersh (Andrey) Budker's Laboratory of New Acceleration Methods at the Institute of Atomic Energy, headed by Igor Kurcharov. Until his death in 1977, academician Gersh Budker was director of the institute. Since then, academician Alexander Skrinsky has served as its director. Scientific and economic policy is controlled by "The Round Table"—the Scientific Council of BINP.

One of the main scientific objectives of BINP is to study elementary particles. The existing scheme to describe elementary particles, the Standard Model, considers as elementary six quarks, six leptons, and four carriers of the fundamental interactions—the photon, the W^± and the Z bosons, and the gluon. All other particles are composite: for example, a proton consists of three quarks (uud) whereas all mesons are quark-antiquark particles. BINP contributed substantially to the development of this picture.

Since the mid-1960s, BINP has studied elementary particles using electron and electron-positron colliders—the most important method in modern elementary particle physics. The institute made many pioneering contributions to the development of this method and to the research in this field, including the work of Gersh Budker, Alexey Naumov, Veniamin Sidorov, and Alexander Skrinsky. From 1965 to 1967 the electron-electron collider VEP-1, simultaneously with the Princeton-Stanford rings, was used to test the Coulomb law at small distances, and it was shown that the electron size does not exceed 10^-14 cm. In the world's first annihilation experiments in electron-positron collisions, carried out at the VEPP-2 collider in 1967, rho-meson parameters were measured. In the experiments performed at VEPP-2 until 1970, the main parameters of vector mesons were studied, and two-photon processes and multiple production of hadrons were discovered. The latter process is an important confirmation of the existence of quarks.

Between 1974 and 2000 the electron-positron collider VEPP-2M, with a productivity that was a hundred times larger, provided much physical information on rare decays of vector mesons. For example, the first evidence for the existence of exotic mesons (possibly four-quark states) was obtained. In these experiments the total cross section of e⁺e^– annihilation was measured with record accuracy in the energy range of 0.36 to 1.4 GeV. At VEPP-4, another e⁺e^– collider operating at BINP, the hadronic cross section was precisely measured between 7.2 and 10.3 GeV. Precise knowledge of the total cross section is important for accurately determining fundamental physical parameters such as the anomalous magnetic moment of the muon and the electromagnetic fine structure constant at high energies. Such experiments will be continued at the new e⁺e^– colliders—the VEPP-4M, which is currently operating, and the VEPP-2000, which is under construction.

The method of resonant depolarization developed at BINP with contributions by Lev Barkov, Lery Kurdadze, Alexey Onuchin, Igor Protopopov, Veniamin Sidorov, Vladimir Smakhtin, Yuri Shatunov, Alexandr Skrinsky, Yuri Tikhonov, and German Tumaykin was successfully applied to establish with very high accuracy (about 10^-5) the absolute mass scale of elementary particles from 1 to 100 GeV. Most of the experiments were performed in Novosibirsk from 1975 through 1984; in 1994 the Z boson mass was measured at the European Laboratory for Particle Physics (CERN).

Parity nonconservation (PNC) in atoms was discovered at BINP. In 1974 Iosif Khriplovich (BINP) proposed an experiment to look for the rotation of the plane of polarization of light passing through atomic bismuth vapor. Simultaneously, this proposal was made at Oxford, UK, and Seattle, Washington. The effect was discovered experimentally by Lev Barkov and Mark Zolotorev in February 1978. It was a vivid demonstration of parity nonconservation, that is, the absence of symmetry between right and left (the plane of polarization of light prefers, say, left rotation to right). In this experiment PNC was first observed as a macroscopic coherent effect. A new kind of weak interaction between electrons and nucleons, resulting from the so-called neutral currents, was first discovered at BINP. It was one of the first decisive confirmations of the unified theory of electroweak interactions.

In 1980 Victor Flambaum and Iosif Khriplovich of BINP predicted that the PNC effects in atoms, which depend on nuclear spin, were due mainly to the so-called nuclear anapole moment (AM). AM corresponds to a special configuration of the electromagnetic field, of the type produced by the current in a toroidal winding. The AM of the cesium nucleus was discovered in an optical experiment in Boulder, Colorado, in 1997.

One of the most frequently cited works in the world is the article on sum rules in quantum chromodynamics by Arkady Vainshtein (BINP) and his Moscow coauthors (1979). Additionally, the most popular model to describe hadron scattering at high energies is the so-called BFKL equation, proposed by Victor Fadin and Eduard Kuraev of BINP in 1975 with his coauthor from Leningrad (now St. Petersburg).

The theoretical discovery of asymptotic freedom was anticipated at BINP. In 1968 Iosif Khriplovich was the first to correctly calculate charge renormalization in the Yang-Mills theory. He pointed out the unusual sign of the effect and gave a simple, intuitive explanation for it.

The electron cooling of the beams of heavy particles was suggested by Gersh Budker in 1966 and realized and developed between 1966 and 1985 at the Budker Institute of Nuclear Physics largely through the efforts of Nikolay Dikansky, Igor Meshkov, Vassli Parkhomchuk, Dmitri Pestrikov, Rustam Salimov, Alexander Skrinsky, and Boris Sukhina. The cooling of beams of charged particles creates a decrease of the phase space occupied by the particles in the storage ring. Cooling substantially increases the particle density in the phase space, compresses the beam, and decreases the spread of particle velocities. This allows one to apply multiple injection to store more and more particles in the phase space sites that become free after cooling.

The electron cooling of the beams of heavy particles is based on the interaction of the beam to be cooled with the cold electron beam. To this end, in one of the straight sections of the storage ring, an electron beam with a small spread of velocities is passed through a circulating beam of heavy particles with the same average velocity. Because of the Coulomb interaction between "cold" electrons and "hot" heavy particles, an intensive heat exchange takes place resulting in the cooling of the heavy particles. The cooling decrements grow proportionally to electron density and decrease rapidly when the angular spread in the ion beam and its energy increase.

The equilibrium of this spread is determined by the equality of the temperatures of electrons and heavy particles:

Because of the large mass difference (m_e and M_i are the electron and ion mass, respectively), the angular spread in the beam of the heavy particles θ_i is much smaller than in the cooling electron beam θ_e.

The longitudinal magnetic field applied for the beam transport further strengthens the cooling action of the electron beam: the transverse thermal motion of electrons is frozen (heavy particles flying far enough away from the electron do not feel their fast rotation in the magnetic field along the Larmor orbits), and the temperature of the longitudinal motion of electrons is often much smaller than the transverse one.

Experiments with electron cooling, even at BINP's first installation, NAP-M, allowed the cooling of the proton beam with an energy of 65 MeV to a temperature of T ∼ 1˚K in the time ∼ 50 ms. Electron cooling is one of the most important techniques in the experimental physics of nuclei and elementary particles, and it is used in laboratories all over the world.

There have been many other important achievements at BINP, for example, the pioneering of a physically self-consistent project of linear colliders able to reach interaction energies ten times higher for electrons, positrons, and photons; and the proposal to reach muon-muon collisions of even higher energy and high luminosity using ionization cooling followed by muon acceleration and storing.

See also:Benefits of Particle Physics to Society; Funding of Particle Physics; International Nature of Particle Physics

Bibliography

Auslender, V., et al. "The Study of Ro-meson Resonance in Electron-Positron Annihilation." Physics Letters25B , 433(1967).

Barkov, L. M., and Zolotarev, M. "Observation of Parity Non-conservation in Atomic Transitions." Soviet Physics: JETP Letters27 , 357 (1978).

Budker, G. I., et al. "Check on Quantum Electrodynamics by Electron-Electron Scattering." Soviet Journal of Nuclear Physics6 (6), 889–892 (June 1968).

Budker Institute of Nuclear Physics. <http://www.inp.nsk.su/>.

Fadin, V. S.; Kuraev, E. A.; and Lipatov, L. N. "On the Pomeranchuk Singularity in Asymptotically Free Theories." Physics LettersB60 , 50–52 (1975).

Khriplovich, I. B. "Feasibility of Observing Parity Nonconservation in Atomic Transitions." Soviet Physics: JETP Letters20 , 315 (1974).

Shifman, M. A.; Vainstein, A. I.; and Zakharov, V. I. "QCD and Resonance Physics. Sum Rules." Nuclear PhysicsB147 , 385–447 (1979).

Skrinsky, A. N., and Shatunov, Y. M. "High Precision Measurements of Elementary Particles Masses using Colliders with Polarized Beams." Soviet Physics USPEKHI32 (6), 548–554 (1989).

Alexander N. Skrinsky