122366617
Ten-dimensional supersymmetric Yang-Mills theory with SO(8)-covariant light-cone superfields
Abstract The ten-dimensional supersymmetric Yang-Mills theory is formulated in terms of light-cone superfields that transform as vectors under the group of transverse Lorentz transformations (SO(8)). These superfields are constrained by a projection condition, which is solved explicitly. The superfield action is obtained by comparing its component expansion with the usual light-cone gauge component action.
121755839
PHASE CONTOURS AND BOOTSTRAPS. I.
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.
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.
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.
59453973
A superconducting focusing solenoid for the neutrino factory linear accelerator
A Superconducting Focusing Solenoid for the Neutrino Factory Linear Accelerator * M. A. Green, V. Lebedev, and B. P Strauss The 400-m long linear accelerator is divided into three sections. Upstream from the linear accelerator is a matching section that provides the first 60 MeV of muon acceleration. The end of the matching section consists of a pair of low stray field solenoids with adjustable currents for tuning. The first section has 4 short modules that are 5-meters long. Each short module has two cells of RF cavities. The second section has 16 medium length modules that are 8-meters long. Each intermediate module has two cells of RF cavities arranged in groups of two with a 1-meter space between groups. The short and intermediate modules have a 1-meter long focusing solenoid with a 1.25-meter long straight section at each end. The third acceleration section has 19 long modules that are 13-meters long. The long module has eight superconducting RF cells arranged in groups of two with a 1-meter space between cell groups. The focusing solenoid is 1.5 meters long with a 1.25-meter long space separating it from the adjacent RF cavity cells. The three types of acceleration modules used for the linear accelerator are illustrated in Figure 1. Unlike focusing quadrupoles, focusing solenoids can produce a stray field that exists some distance from the magnet. The superconducting RF cavities are sensitive to magnetic fields even at the level of 0.0001 T (versus 0.043 T for the smallest single solenoid in Table 1), so a key parameter in the focusing solenoid design is getting rid of the solenoid stray field in the RF cavities. The methods one can use to eliminate the stray field in the RF cavities are:1) The focusing solenoid should produce zero net magnetic moment[5,6]. This means that the coil that produces the field is bucked by a coil that is larger in diameter. 2) The field from the bucking coils should be distributed in the same way as the solenoid field. This suggests that the bucking solenoid be around the focusing solenoid so that the return flux from the focusing solenoid is returned between the focusing solenoid and the bucking solenoid[7]. 3) The nested solenoids should be surrounded by iron except where the muon beam passes through the solenoid. 4) An iron flux shield should be installed between the focusing solenoid and the RF cavities. 5) If the stray field is still not low enough, the RF cavities can be covered with a type 2 superconducting shield. This shield will trap earth’s magnetic field, but it will shield out the remaining stray flux from a nearby solenoid provided the cavities are cold (below 5 K) when the solenoid is turned on. An iron shielded actively shielded solenoid appears to be a minimum requirement in order to reduce the stray field to an acceptable level. Abstract--The proposed linear Accelerator that accelerates muons from 190 MeV to 2.45 GeV will use superconducting solenoids for focusing the muon beam. The accelerator will use superconducting RF cavities. These cavities are very sensitive to stay magnetic field from the focusing magnets. Superconducting solenoids can produce large stray fields. This report describes the 201.25 MHz acceleration system for the neutrino factory. This report also describes a focusing solenoid that delivers almost no stray field to a neighboring superconducting RF cavity. Index Terms—Superconducting Focusing Solenoid, Active Shielding, Superconducting RF Cavities I. I NTRODUCTION The proposed neutrino factory generates neutrinos from muon decay in a muon storage ring[1,2]. The muons are created from the decay of pions produced from the collision of protons on a fixed target. The pions are captured by a 20 T solenoid. The pions then decay to muons as they pass down a long channel. The muons are phase-rotated, bunched, and cooled before they can be accelerated and stored in the storage ring[3]. The first stage of acceleration is a linear accelerator that uses superconducting RF cavities[4]. Muon focusing during this acceleration occurs within superconducting solenoids. After the muons are accelerated to 2350 MeV, they enter a re- circulating linac that accelerates them to their final energy of 20 GeV. The 20 GeV muons are then stored in storage ring where they decay to two neutrinos and an electron or positron (depending on the charge of the originating muon type). II. F OCUSING S OLENOIDS FOR THE L INEAR A CCELERATOR The proposed linear accelerator that accelerates the muons from 190 MeV to 2350 MeV extends nearly 400 meters. The Linear accelerator will use high gradient superconducting RF cavities to accelerate the beam. These cavities will not only increase the acceleration gradient, but they will also save electric power. Between the RF cavities there will be superconducting solenoids that provide beam focusing. Received 26 September 2001 * This work was supported by the Office of Science, United States Department of Energy under DOE contract number DE-AC03-76SF00098 M. A. Green, is from the Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA;V. Lebedev, is from the Thomas Jefferson National Laboratory, Newport News VA 23606, USA; B. P Strauss is from the U S Department of Energy, Germantown MD 20874, USA
118961628
A LARGE HIGH CURRENT DENSITY SUPERCONDUCTING SOLENOID FOR THE TIME PROJECTION CHAMBER EXPERIMENT
TWO-WEEK LOAN COpy This is a Library irculating Copy which may be borrowed for two weeks. For a personal retention copy, call Tech. Info. Diuision, Ext. 6782
122003703
Quench back in thin superconducting solenoid magnets
Abstract Superconducting magnets with well coupled, low resistance, secondary circuits have been observed to become fully normal faster than quench propagation in the coil would permit. This process is referred to as ‘quench back’. Quench back observed at the Lawrence Berkeley Laboratory (LBL) was caused by heating the secondary circuit from the current induced from the primary circuit as normal region in the superconducting coil propagated. This paper develops the theory for thermal quench back in thin solenoid magnets and compares this theory with measurements made in two one-meter diameter superconducting solenoid magnets.
25710510
How the Performance of a Superconducting Magnet Is Affected by the Connection Between a Small Cooler and the Magnet
As low temperature cryocoolers become more frequently used to cool superconducting magnets, it becomes increasingly apparent that the connection between the cooler and the magnet has an effect on the design and performance of the magnet. In general, the use of small coolers can be considered in two different temperature ranges; 1) from 3.8 to 4.8 K for magnet fabricated with LTS conductor and 2) from 18 to 35 K for magnets fabricated using HTS conductor. In general, both temperature ranges call for the use of a two-stage cooler. The best method for connecting a cooler to the magnet depends on a number of factors. The factors include: 1) whether the cooler must be used to cool down the magnet from room temperature, 2) whether the magnet must have one or more reservoirs of liquid cryogen to keep the magnet cold during a loss of cooling, and 3) constraints on the distance from the cooler cold heads and the magnet and its shield. Two methods for connecting low temperature coolers to superconducting magnets have been studied. The first method uses a cold strap to connect the cold heads directly to the loads. This method is commonly used for cryogen-free magnets. The second method uses a thermal siphon and liquid cryogens to make the connection between the load being cooled and the cold head. The two methods of transferring heat from the magnet to the cooler low temperature cold head are compared for the two temperature ranges given above
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.