摘要:

The design of new and upgrades of existing high energy particle accelerators is reviewed in light of the current knowledge of the Standard Model determined from existing and past machines and funding factors. Current financing of science will delay determining unknowns, such as CP violation, proton decay, neutrino properties, and dark matter. Three options are given: (1) obtain more funding, (2) downsize scientific personnel as are private enterprises or (3) develop new technology which will reduce the high cost of building current designs of high energy accelerators. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49610

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The design of new and upgrades of existing high energy particle accelerators is reviewed in light of the current knowledge of the standard model determined from existing and past machines and funding factors. Current financing of science will delay determining unknowns, such as CP violation, proton decay, neutrino properties, and dark matter. Three options are given: (1) obtain more funding, (2) downsize scientific personnel as are private enterprises or (3) develop new technology which will reduce the high cost of building current designs of high energy accelerators. (AIP) ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49594

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Beams may be viewed as directed and focussed flow of energy and information, carried by particles and electromagnetic radiation fields (i.e. photons). Often, they are brought into interaction with each other (e.g. in high energy colliders) or with other forms of matter (e.g. in fixed target physics, synchrotron radiation sciences, neutron scattering experiments, laser chemistry and physics, medical therapy, etc.). The whole art and science of beams revolve around the fundamental quest for, and ultimate implementation of, mechanisms of production, storage, control and observation of beams—always directed towards studies of the basic structures and processes of the natural world and various practical applications. Tremendous progress has been made in all aspects of beam physics and technology in the last decades—nonlinear dynamics, superconducting magnets and radio frequency cavities, beam instrumentation and control, novel concepts and collider paradigms, to name a few. We will illustrate this progress via a few examples and remark on the emergence of new collider scenarios where some of these progress might come to use—the Gamma‐Gamma Collider, the Muon Collider, laser acceleration, etc. We will close with an outline of future opportunities and outlook. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49603

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

In July 1994 a workshop was held at Indiana University to study and discuss options for future hadron collider facilities in the United States, and to identify related R&D programs. The workshop was conducted under the auspices of the Accelerator Physics, Technologies, and Facilities Working Group of the DPF Long Term Planning Study. Roughly 50 participants from 17 institutions in the U.S. and Europe (CERN) were organized into six working groups to study magnets, cryogenics and vacuum, antiproton sources, injectors, interaction regions, and lattice and beam dynamics. Upgrades to existing facilities (namely, Fermilab) and a post‐LHC facility were discussed at the workshop. In this paper, the discussion will focus on the post‐LHC facility. One of the specific goals of the workshop was to develop a defensible parameters list for a 30 TeV×30 TeV hadron collider with luminosity of 1×1034cm−2 sec−1. While this accelerator would have only 50% higher energy than the SSC design, it was realized that the role of synchrotron radiation at this energy would significantly enhance the design and operation of the machine. Radiation damping times of a few hours, rather than one day, can be realized thus allowing less intense, but brighter proton beams. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49620

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

An accelerator can be called ‘‘Mo¨bius’’ if it contains a ‘‘twist’’ element that forces a particle to complete two traversals of the ring before returning to a corresponding state. The resultant ring has properties very different from an untwisted lattice. Since chromaticity correction needs only to be performed in one plane, it can be done entirely in the (easy) horizontal plane, with &pgr;‐separated, non‐interleaved, sextupole pairs. This permits increased focusing strength while preserving large amplitude stability. In colliding beam operation, the (round) beams are robust against beam‐beam interaction. Simulation indicates that beams counter‐rotating in the same chamber need not be separated even for accumulated small‐amplitude tune shifts greatly exceeding one. The large resulting tune spreads are found to stabilize the beams against head‐tail instability with greater‐than‐typical head‐tail tune shifts. Since stabilization relies at present on synchrotron oscillations with chromaticity near zero, the sextupoles needed for this, and the large‐amplitude degradation they cause, may be superfluous. Stable operation is possible with beam‐beam tune shifts well in excess of 0.1 at the main experiment crossing points. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49621

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The RARF has a heavy‐ion accelerator complex consisting of a K540‐MeV ring cyclotron as a booster accelerator and two different types of injectors. The facility provides not only nuclear physicists but also researchers of atomic physics, nuclear chemistry, material science, radiobiology and others with various kinds of heavy‐ion beams of an energy range of 10 MeV/nucleon to 100 MeV/nucleon. One of remarkable features of this facility is capability of supplying RI (radioactive isotope) beams with the world‐highest level of intensities. In these several years the RI beam has opened up a quite new and fascinating heavy‐ion science. In order to further promote this new science, we propose ‘‘RIKEN RI Beam Factory’’ as a future project of the RARF: The existing facility will be expanded into the ‘‘Factory’’ where high‐intensity RI beams of the whole mass range will become available in a wide energy range up to several hundred MeV/nucleon. The concept of this new proposal as well as currently‐running upgrade programs relevant to the project will be presented. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49623

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

High energy particle colliders are probably the most sophisticated machines ever built. Colliding beams have to be kept stable for many hours, and beam parameters should be preserved for delivering maximal information to the physicists. Several promising directions for improvements in high energy collider performance have been initiated by the author and reported in scientific publications and related patent documentation. The question of extraction of the beam halo by means of a bent crystal is elaborated below. Halo particles of high energy beams would be extracted from colliders with high efficiency without interference with colliding beam experiments. This would eliminate irradiation of accelerator parts by the beam halo, creating more favorable environmental situation at accelerators. The extracted beam could be used for parasitic experiments, or disposed of in an environmentally controlled manner. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49622

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Longitudinal oscillations have been excited in debunched beams in several of the Fermilab synchrotrons, which indicate, under certain conditions, the occurrence of a variety of nonlinear coherent phenomena. These phenomena indicate that mode saturation and longitudinal emittance growth may be influenced by classical processes such as three‐wave coupling and wave overturning due to self‐trapping. The purpose of these studies was to determine the intrinsic machine impedance and the response of the beam to longitudinal perturbations using standard beam‐transfer function measurements. However, experimental observations indicated that the expected linear response regime was absent over a wide range of experimental conditions, consistent with the fact that these machines are longitudinally near marginal stability. The beam response was characterized by resonant three‐wave mode‐mode coupling and by a slow echo‐like phenomenon suggesting phase space rotation. A theoretical investigation was undertaken to ascertain the nature of this response. Using a well‐known perturbative approach, nonlinear coupling thresholds were derived for the onset of the three‐wave interaction and were found to be consistent with measured conditions in the beam. In addition, particle simulations were carried out to attempt to explain mode saturation effects and the long‐time behavior. The results indicate that a temporal mode cascade can occur as a consequence of the three‐wave interaction. Also, self‐trapping in an impedance‐induced potential well, accompanied by phase rotation, may take place, and this effect appears to be associated with pump depletion of the driving mode in the three‐wave interaction. These phenomena play a key role in determining the emittance growth associated with the long‐term approach to equilibrium. The results also suggest methods to use the experimental observations to determine the machine impedance in an qualitative way. Details of the measurements and a development of the theoretical concepts will be given. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49601

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

It is well‐known that, when the bunch current in an electron storage ring exceeds a certain value, the bunch length becomes longer than the natural length determined by the balance between the radiation damping and excitation. The threshold current can be estimated by the linearized Vlasov equation, but the problem of the bunch length above threshold cannot be treated by the linear theory. In the present report, we discuss a method which gives a steadily oscillating state above threshold in the framework of the quasilinear method in the plasma physics. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49595

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The vertical emittance in a low emittance synchrotron light source is almost determined by linear coupling. But this emittance, i.e. normalized phase space area, varies point by point along a ring on the contrary to the general understanding of linear coupling resonances. The phenomena are described by the perturbative approach and the algorithm for the complete correction of ‘‘emittance modulation’’ is proposed. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49602

出版商:AIP    

年代:1996

数据来源: AIP