122189895
String field theory with chiral coordinates
Interesting string theories, such as the heterotic string, involve chiral coordinates, that is coordinates which are either right-moving or left-moving on the world sheet. In this paper the field theoretic formulation of such theories is studied with most emphasis on the light-cone gauge method although the main techniques would also apply in the various covariant approaches to string field theory. In the heterotic string the internal symmetry is described in terms of eight left-moving complex bosonic coordinates in a manner which parallels the treatment of fermionic Grassmann coordinates. The wave functions, and hence the free string fields, are described in these coordinates and the three-string interaction is derived from the requirements of supersymmetry and Lorentz invariance both in its functional form and in terms of its oscillator modes.
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.
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.
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.
121120579
The two-coil toroid magnet, an option for ASTROMAG
The ASTROMAG particle astrophysics experiment for the US space station requires a magnetic field in order to determine the energy and momentum of charged particles of various momenta. A second concept for generating magnetic field for ASTROMAG is presented. This magnet configuration consists of two D-shaped coils which form a two-coil toroid. The two coils are located within a paddle connected to a spherical helium tank. The physics detectors would be located on either side of the flat paddle. The particles travel toward the tank in a direction approximately parallel to the paddle surface. A description is given of the two-coil toroid, the magnet cryostat, and the helium II cryogenic system, which keeps the magnet cold for up to two years without refilling. >
124315608
Proposal to Construct an anti-Proton Source for the Fermilab Accelerator
We propose to build a small storage ring for the accumulation of antiprotons produced in an external target. Stochastic and electron cooling will be used to reduce the transverse and longitudinal phase space of the antiprotons. The dynamics of stochastic and electron cooling will also be studied in this storage ring using circulating protons. The cooled antiprotons can be re-injected into the main ring or energy doubler ring; after simultaneous acceleration along with a proton bunch the accelerator will become a colliding {bar}pp machine with a center of mass energy range of 300-2600 GeV. Luminosities in the range 10{sup 29}-10{sup 32} cm {sup -2}sec{-1} are expected.
122984815
THE OPERATION OF A FORCED TWO PHASE COOLING SYSTEM ON A LARGE SUPERCONDUCTING MAGNET
This paper describes the operation of a forced two phase cooling system on a two meter diameter superconducting solenoid. The magnet is a thin high current density superconducting solenoid which is cooled by forced two phase helium in tubes around the coil. The magnet, which is 2.18 meters in diameter and 3.4 meters long, has a cold mass of 1700 kg. The two phase cooling system contains less than 300 liters of liquid helium, most of which is contained in a control dewar. This paper describes the operating characteristics of the LBL two phase forced cooling system during cooldown and warm up. The paper presents experimental data on operations of the magnet using either a helium pump or the refrigerator compressor to circulate two phase helium through the superconducting coil cooling tubes.
54880209
The effect of low temperature cryocoolers on the development of low temperature superconducting magnets
The commercial development of reliable 4 K cryocoolers improves the future prospects for magnets made from low temperature superconductors (LTS). The hope of the developers of high temperature superconductors (HTS) has been to replace liquid helium cooled LTS magnets with HTS magnets that operate at or near liquid nitrogen temperature. There has been limited success in this endeavor, but continued problems with HTS conductors have greatly slowed progress toward this goal. The development of cryocoolers that reliably operate below 4 K will allow magnets made from LTS conductor to remain very competitive for many years to come. A key enabling technology for the use of low temperature cryocoolers on LTS magnets has been the development of HTS leads. This report describes the characteristics of LTS magnets that can be successfully melded to low-temperature cryocoolers. This report also shows when it is not appropriate to consider the use of low-temperature cryocoolers to cool magnets made with LTS conductor. A couple of specific examples of LTS magnets where cryocoolers can be used are given.
6205052
The Effect of Magnetic Field on the Position of HTS Leads and the Cooler in the Services Tower of the MICE Focusing Magnet
The MICE focusing solenoids have three 4 K coolers (two for the superconducting magnet and one for the liquid absorber) and four HTS leads that feed the current to the focusing coils. The focusing solenoids produce large radial external fields when they operate with the polarity of the two coils in opposition (the gradient or flip mode). When the MICE focusing coils operate at the same polarity (the solenoid or non-flip mode), the fields are much smaller and parallel to the axis of the solenoid. The worst-case magnetic field affects the selection of the cooler and the HTS leads. This magnetic field can also determine the height of the service towers that house the three coolers and the four HTS leads. This paper shows the criteria used for Cooler selection, HTS lead selection, and the position of both the cooler and leads with respect to the solenoid axis of rotation.