121541003
TWO-BODY UNITARITY AND THE ASYMPTOTIC DUALITY SERIES.
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.
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.
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.
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.
120565313
Correction of the field in the SSC dipoles using superconductor on the wedges
The Superconducting Super Collider magnet coil has three wedges separating the superconducting coil blocks on its inner layer. It is shown how if the wedges have superconductors attached, one can correct all of the magnetic field multipoles (both normal and skew) from N=1 (dipole) to N=6 (12 pole). Wedge correction winding orientation, dimensions, and peak currents needed are described. The tradeoff required for using this correction method is additional complication of the dipole magnets and additional He refrigeration needed to cool the extra magnet leads. This refrigeration can be reduced by putting the wedges in six dipole magnets in series. However, wedge correction will result in the elimination of continuous bore-tube correction coils and it could result in simplification of the SSC lumped correction magnet system. >
125011989
Lessons Learned for the MICE Coupling Solenoid from the MICE Spectrometer Solenoids
LESSONS LEARNED FOR THE MICE COUPLING SOLENOID FROM THE MICE SPECTROMETER SOLENOIDS* M. A. Green a , L. Wang b , H. Pan c , H. Wu c , X. L. Guo c , S. Y. Li d , S. X. Zheng c , S. P. Virostek a , A. J. DeMello a , D. Li a , F. Trillaud a , and M. S. Zisman a , a) LBNL, Berkeley CA, USA, b) Shanghai Institute of Applied Physics, Shanghai, China c) ICST, HIT, Harbin, China, and d) Hilong University of Science and Technology, Harbin, China Abstract Tests of the spectrometer solenoids have taught us some important lessons. The spectrometer magnet lessons learned fall into two broad categories that involve the two stages of the coolers that are used to cool the magnets. On the first spectrometer magnet, the problems were centered on the connection of the cooler 2nd-stage to the magnet cold mass. On the first test of the second spectrometer magnet, the problems were centered on the cooler 1st- stage temperature and its effect on the operation of the HTS leads. The second time the second spectrometer magnet was tested; the cooling to the cold mass was still not adequate. The cryogenic designs of the MICE and MuCOOL coupling magnets are quite different, but the lessons learned from the tests of the spectrometer magnets have affected the design of the coupling magnets. This paper compares the magnet cryogenic design for the spectrometer magnet [4] and the coupling magnet [5]. The effect of magnetic fields on the high temperature superconductor (HTS) leads is discussed [6]. The experience gained from testing the spectrometer magnets has influenced the design of the coupling magnets. Lessons learned from the spectrometer magnets will likely affect the AFC magnet design [7] as well. SPECTROMETER AND COUPLING MAGNET DESIGN COMPARISON The spectrometer solenoid cryostat has an OD of 1.4 m and it is 2.7-m long. The coupling magnet cryostat has an OD of more than 2.2 m and a length of 0.49 m. The magnets are quite different. The spectrometer solenoid is long (2511 mm) compared to its coil ID of 516 mm. On other hand the coupling magnet coil is short (285 mm) compared to its coil ID of 1500 mm. As a result, the stray field outside the coupling magnet is large compared to the spectrometer magnet. The stray field of the coupling magnet affects the location and orientation of the HTS leads and it influences the design first-stage temperature for the coolers that cool the magnet. Table 1 compares the design heat loads for the two types of MICE magnets. Table 1: A Comparison of the Design Cryogenic Heat Loads for the Spectrometer and Coupling Magnets Parameter Spectro. Coupl. Number of 4.2 K coolers Total Lead Current (A) (No. Leads) Cold Mass Support Design Force (kN) Total Shield Area (m 2 ) Number of Wires to Shield Number of wires to Cold Mass Calculated 1st Stage Heat Loads Lead Conduction + I 2 R heating (W) Cold Mass Support heat Load (W) MLI Heat Load (W) Pipe and Sleeve Heat Load (W) Instrumentation Heat Load (W Total Design 1 st Stage Heat Load (W) Per Cooler 1 st Stage Heat Load (W) Calculated 2 nd Stage Heat Loads Lead Conduction + I 2 R heating (W) Cold Mass Support heat Load (W) MLI Heat Load (W) Pipe and Sleeve Heat Load (W) Instrumentation Heat Load (W) Total Design 2 nd Stage Heat Load (W) Per Cooler 2 nd Stage Heat Load (W) INTRODUCTION The muon ionization cooling experiment (MICE) will be a demonstration of muon cooling in a configuration that may be useful for a neutrino factory [1]. Stage 6 of MICE (the final MICE channel) consists of: 1) two spectrometer modules used for analyzing muon beam emittance before and after cooling; 2) three absorber focus coil (AFC) modules used for muon ionization cooling in the absorbers in the focusing magnets; and 3) two RF coupling coil (RFCC) modules are used for reaccelerating the muon beam between the AFC modules. The RFCC modules consist of a superconducting coupling solenoid, which surrounds a 1.4-meter diameter vacuum chamber that contains four separately powered conventional copper RF cavities that have a resonant frequency of 201.25 MHz. The individual RF cavity irises are closed by thin beryllium windows [2]. The coupling magnet will produce a large enough magnetic field to keep the beam within the iris of the RF cavities. The magnets used in the MICE cooling channel are all superconducting solenoids. All of the MICE cooling channel magnet modules are cooled using two-stage pulse tube coolers that develop 1.5 W of cooling at 4.2 K while generating 50 W of cooling at 45 K [3]. The channel magnets are continuously powered by one or more pairs of leads that go from 300 K to the cold mass. The magnet current leads between the first and second stages of the coolers are made from HTS conductor. The leads from 300 K to the cooler first-stages are conduction cooled. * This work is supported by the Office of Science, US Department of Energy under DOE contract DE-AC02-05CH11231. This work is also supported by funds of the cryogenic and technology innovation project under the “985-2” plan of the Harbin Institute of Technology.
10009205
Quench Protection for the MICE Cooling Channel Coupling Magnet
This paper describes the passive quench protection system selected for the muon ionization cooling experiment (MICE) cooling channel coupling magnet. The MICE coupling magnet will employ two methods of quench protection simultaneously. The most important method of quench protection in the coupling magnet is the subdivision of the coil. Cold diodes and resistors are put across the subdivisions to reduce both the voltage to ground and the hot-spot temperature. The second method of quench protection is quench-back from the mandrel, which speeds up the spread of the normal region within the coils. Combining quench back with coil subdivision will reduce the hot spot temperature further. This paper explores the effect on the quench process of the number of coil sub-divisions, the quench propagation velocity within the magnet, and the shunt resistance.
39000483
Preliminary Test Results for the MICE Spectrometer Superconducting Solenoids
This report describes the MICE spectrometer solenoids as built. Each magnet consists of five superconducting coils. Two coils are used to tune the beam going from or to the MICE spectrometer from the rest of the MICE cooling channel. Three spectrometer coils (two end coils and a long center coil) are used to create a uniform 4 T field (to plusmn0.3 percent) over a length of 1.0 m within a diameter of 0.3 m. The three-coil spectrometer set is connected in series. The two end coils use small power supplies to tune the uniform field region where the scintillating fiber tracker is located. This paper will present the results of the preliminary testing of the first spectrometer solenoid.
56066198
Power Supply and Quench Protection for the MICE Channel Magnets
LBNL-59004 SCMAG-855 MICE-PUB-GEN-132 Power Supply and Quench Protection for the MICE Channel Magnets* Michael A. Green 1 , and Holger Witte 2 1. Lawrence Berkeley National Laboratory, Berkeley CA 94703, USA 2. Oxford University Physics Department, Oxford OX1-3PU, UK September 2005 Presented at the 2005 European Applied Superconductivity Conference Vienna, Austria 11 through 14 September 2005 * This work was supported by the Oxford University Physics Department and the Particle Physics and Astronomy Research Council of the United Kingdom. This work was also performed at the Lawrence Berkeley National Laboratory with the support of the Office of High Energy Physics, United States Department of Energy under DOE contract DE-AC02- 05CH11231. DOE funding for the US Neutrino Factory and Muon Collider Collaboration is gratefully acknowledged.