119043809
Connections between M-theory and superstrings
This article reviews the non-perturbative structure of certain higher derivative terms in the type II string theory effective action and their connection to one-loop effects in eleven-dimensional supergravity compactified on a torus. New material is also included that was not presented in the talks.
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.
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.
121755839
PHASE CONTOURS AND BOOTSTRAPS. I.
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.
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.
21171946
Progress on the MICE Tracker Solenoids
The first magnets for the muon ionization cooling experiment will be the tracker solenoids that form the ends of the MICE cooling channel. The primary purpose of the tracker solenoids is to provide a uniform 4 T field (to better than plusmn0.3 percent over a volume that is 1 meter long and 0.3 meters in diameter) spectrometer magnet field for the scintillating fiber detectors that are used to analyse the muons in the channel before and after ionization cooling. A secondary purpose for the tracker magnet is the matching of the muon beam between the rest of the MICE cooling channel and the uniform field spectrometer magnet. The tracker solenoid is powered by three 300 amp power supplies. Additional tuning of the spectrometer is provided by a pair of 50 amp power supplies across the spectrometer magnet end coils. The tracker magnet will be cooled using a pair of 4 K pulse tube coolers that each provide 1.5 W of cooling at 4.2 K. Final design and construction of the tracker solenoids began during the summer of 2006. This report describes the progress made on the construction of the tracker solenoids.
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.
54925012
MEASUREMENT OF RESISTANCE AND STRENGTH OF CONDUCTOR SPLICES IN THE MICE COUPLING MAGNETS
The superconducting magnets for the Muon Ionization Cooling Experiment [1] (MICE) use a copper based Nb‐Ti conductor with un‐insulated dimensions of 0.95 by 1.60 mm. There may be as many as twelve splices in one MICE superconducting coupling coil. These splices are to be wound in the coil. The conductor splices produce Joule heating, which may cause the magnet to quench. A technique of making conductor splices was developed by ICST. Two types of 1‐meter long of soldered lap‐joints have been tested. Side‐by‐side splices and up‐down one splices were studied theoretically and experimentally using two types of soft solder made of eutectic tin‐lead solder and tin‐silver solder. The resistances of the splices made by ICST were tested at LBNL at liquid helium temperatures over a range of magnetic fields up to 5 T. The breaking strength of 250 mm long splices was also measured at room temperature and liquid nitrogen temperature.
136567622
Ferromagnetic Material in the Superconductor and Its Effect on the Magnetization Sextupole and Decapole in the SSC Dipoles at Injection
It has been shown that the magnetization of a multi-filamentary superconductor can be altered by adding nickel to the composite strand. This report presents the results of calculations of the magnetization sextupole and higher multipoles in a 5 cm Superconducting Super Collider (SSC) dipole with and without nickel as part of the strand composite. The relative distribution of the nickel in the inner and outer coil conductors can be used to effectively eliminate sextupole and decapole at the SSC dipole injection field. Calculations of magnetization sextupole in the dipole are presented for strand with substituted nickel filaments and strand with electroplated nickel. The effect of nickel in the strand on the SSC dipole field quality at fields above the injection field is described. The effect of nickel in the strand on magnetization sextupole flux creep decay and the magnetization sextupole temperature dependence is also discussed.
121004261
A burnout safety condition for superconducting magnets and some of its applications
From the time evolution of the current in a superconducting coil during a quench, an upper limit can be computed for the temperature reached anywhere in the coil. A condition under which the danger of burnout is eliminated is derived here. It is used to show how the tests of superconducting magnets can be made safe against burnout and it provides constraints for the design of some type of magnets.