120391337
Dynamical point-like structure and dual strings
Abstract The emission of zero momentum scalar particles into the vacuum from dual strings is shown to be equivalent to the insertion of point-like energy densities on the strings. This suggests a physically plausible procedure for modifying the dual model to incorporate point-like structure leading, for example, to power behaved large angle elastic scattering.
121755839
PHASE CONTOURS AND BOOTSTRAPS. I.
9607753
Anomalous creation of branes
In certain circumstances when two branes pass through each other a third brane is produced stretching between them. We explain this phenomenon by the use of chains of dualities and the inflow of charge that is required for the absence of chiral gauge anomalies when pairs of D-branes intersect.
120539667
Anomaly cancellations in supersymmetric D = 10 gauge theory and superstring theory☆
Abstract Supersymmetric ten-dimensional Yang-Mills theory coupled to N = 1, D = 10 supergravity has gauge and gravitational anomalies that can be partially cancelled by the addition of suitable local interactions. The remaining pieces of all the anomalies cancel if the gauge group is SO(32) or E 8 × E 8 . These cancellations are automatically incorporated in the type I superstring theory based on SO(32). A superstring theory for E 8 × E 8 has not yet been constructed.
123230985
Off-shell states in the dual model
Abstract We present a class of Lorentz invariant, gauge invariant off-shell amplitudes for the ordinary Veneziano and Ramond-Neveu-Schwarz dual models. They correspond to interactions with the string which are local in space-time.
121062482
N=4 Yang-Mills and N=8 Supergravity as Limits of String Theories
The formulation of supersymmetric string theories in ten dimensions is generalized to incorporate compactified dimensions. Expressions for the one-loop four-particle S -matrix elements of N = 4 Yang-Mills and N = 8 supergravity in four dimensions are obtained by studying the string-theory loop amplitudes in the limit that the radii of the compactified dimensions and the Regge slope parameter simultaneously approach zero. If certain patterns that emerge should persist in the higher orders of perturbation theory, then N = 4 Yang-Mills in four dimensions would be ultraviolet finite to all orders, whereas N = 8 supergravity in four dimensions would have ultraviolet divergences starting at three loops.
117741073
Measurements of Magnetization Multipoles in Four Centimeter Quadrupoles for the SSC
Higher multipoles due to magnetization of the superconductor in superconducting dipole and quadrupole magnets has been observed in over twenty years. This report presents measurements of the 12 pole and 20 pole multipoles in a model one-meter long four-centimeter bore SSC type quadrupole built at the Lawrence Berkeley Laboratory (LBL). The measurements were compared with calculations of the field structure using magnetization theory. Good agreement was observed between the measured multipoles and the calculated multipoles. Under conditions equivalent to injection into the SSC at an energy of 2 TeV, about 1.0 unit of 12 pole was observed and 0.05 units of 20 pole was observed. (One unit of field error is a field error of one part in ten thousand). Magnetization multipole measurements were also done on the first full length (5 meter) SSC quadrupole prototype. Measurements of flux creep decay were made on three one meter quadrupoles and the first five meter long quadrupole. 7 refs., 9 figs.
122611866
Large diameter thin superconducting solenoid magnets
Abstract High energy physics experiments on the latest generation colliding beam machines require large superconducting solenoid magnets. The Lawrence Berkeley Laboratory is developing a new generation of high current density (∼ 10 9 A m −2 ) superconducting solenoid magnets which are thin from a radion standpoint. To meet our design objectives, an integrated magnet and cryostat design has been evolved. Recent tests of one metre diameter prototype magnets show that our design concepts are technically viable. The results of the one metre magnet test are reported here.
59157285
Refrigeration options for the Advanced Light Source Superbend Dipole Magnets
The 1.9 GeV Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL) produces photons with a critical energy of about 3.1 keV at each of its thirty-six 1.3 T gradient bending magnets. It is proposed that at three locations around the ring the conventional gradient bending magnets be replaced with superconducting bending magnets with a maximum field of 5.6 T. At the point where the photons are extracted, their critical energy will be about 12 keV. In the beam lines where the SuperBend superconducting magnets are installed, the X ray brightness at 20 keV will be increased over two orders of magnitude. This report describes three different refrigeration options for cooling the three SuperBend dipoles. The cooling options include: 1) liquid helium and liquid nitrogen cryogen cooling using stored liquids, 2) a central helium refrigerator (capacity 70 to 100 W) cooling all of the SuperBend magnets, 3) a Gifford McMahon (GM) cryocooler on each of the dipoles. This paper describes the technical and economic reasons for selecting a small GM cryocooler as the method for cooling the SuperBend dipoles on the LBNL Advanced Light Source.
117480318
High field solenoids for muon cooling
I LBNL-44189 SC-MAG-688 High Field Solenoids for Muon Cooling M. A. Green a , Y. Eyssa b , S. Kennyb, J. R. Miller b and S. Prestemon b a Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA b National High Magnetic Field Laboratory, Tallahassee FL 32310, USA September 1999 Fourth European Conference on Applied Superconductivity Sitges, Spain, 14 through 17 September 1999 To be Published in the EUCAS-99 Proceedings This work was performed at the Lawrence Berkeley National Laboratory with the support of the Director, Office of Science, U. S. Department of Energy under Contract No. DE-AC03- 76SF00098.
54854389
The Effect of Extending the Length of the Coupling Coils in a Muon Ionization Cooling Channel
RF cavities are used to re-accelerate muons that have been cooled by absorbers that are in low beta regions of a muon ionization cooling channel. A superconducting coupling magnet (or magnets) are around or among the RF cavities of a muon ionization-cooling channel. The field from the magnet guides the muons so that they are kept within the iris of the RF cavities that are used to accelerate the muons. This report compares the use of a single short coupling magnet with an extended coupling magnet that has one or more superconducting coils as part of a muon-cooling channel of the same design as the muon ionization cooling experiment (MICE). Whether the superconducting magnet is short and thick or long and this affects the magnet stored energy and the peak field in the winding. The magnetic field distribution also affects is the muon beam optics in the cooling cell of a muon cooling channel.