121538117
Duality constraints in inclusive reactions
Abstract A possible implementation of the Harari-Freund conjecture on a dual model is shown to lead to the vanishing of the pomeron-pomeron-reggeon coupling and a unique criterion for the absence of nonscaling (secondary) terms in inclusive reactions.
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.
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.
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.
121755839
PHASE CONTOURS AND BOOTSTRAPS. I.
118295670
Progress on Superconducting Magnets for the MICE Cooling Channel
MICE Note 274 Progress on the Superconducting Magnets for the MICE Cooling Channel M. A. Green a , S. P. Virostek a , D. Li a , M. S. Zisman a , L. Wang b , H. Pan b , H. Wu b , X. L. Guo b , F. Y. Xu b , X. K. Liu, S. X. Zheng b , T. Bradshaw c , D. E. Baynham c , J. Cobb d , W. Lau d , P. Lau d , and S. Q. Yang d , a) Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA b) Institute of Cryogenic and Superconductivity Technology, HIT, Harbin, China c) Rutherford Appleton Laboratory, Chilton Didcot OX11-0QX, UK d) Physics Department Design Office, Oxford University, Oxford OX1-3RH, UK Corresponding Author: Michael A. Green at magreen@lbl.gov Abstract. The muon ionization cooling experiment (MICE) consists of a target, a beam line, a pion decay channel, the MICE cooling channel. Superconducting magnets are used in the pion decay channel and the MICE cooling channel. This report describes the MICE cooling channel magnets and the progress in the design and fabrication of these magnets. The MICE cooling channel consists of three types of superconducting solenoids; the spectrometer solenoids, the coupling solenoids and the focusing solenoids. The three types of magnets are being fabricated in the United States, China, and the United Kingdom respectively. The spectrometer magnets are used to analyze the muon beam before and after muon cooling. The coupling magnets couple the focusing sections and keep the muon beam contained within the iris of the RF cavities that are used to recover the muon momentum lost during ionization cooling. The focusing magnets focus the muon beam in the center of a liquid hydrogen absorber. The first of the cooling channel magnets will be operational in MICE in the spring of 2010. 1. Introduction to the MICE Cooling Channel The next generation of particle physics accelerators will involve the acceleration and collision of high- energy leptons. There are limits on how much the lowest mass stable lepton (electrons and positrons with a rest mass of 0.51 MeV) can be bent in a magnetic field. The next lowest mass lepton is the muon (rest mass ~100 MeV). High-energy muons can be bent without the synchrotron radiation that comes from bending electrons or positrons. Muons are produced from the decay of pions, which are produced when protons collide with a fixed target. Muons produced this way have a high emittance. The development of a neutrino factory or a muon collider requires that muon-beams be cooled (reducing their emittance by removing the transverse momentum while retaining the momentum in the direction of the beam). Because a muon has a short lifetime (~2.1 µs at rest), the methods used for cooling positrons and anti protons cannot be employed. The only method that can be applied that will cool muons within their lifetime is ionization cooling. Demonstrating muon ionization cooling is essential to the development of muon accelerators and storage rings [1], [2]. The muon ionization cooling experiment (MICE) is designed to demonstrate muon cooling in a magnet configuration that is useful for a neutrino factory [3], [4].
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.
122299493
The Effect of Flux Creep on the Magnetization Field in the SSC Dipole Magnets
The sextupole fields of model SSC dipole magnets have been observed to change with time when the magnets are held at constant current under conditions similar to injection into the SSC accelerator. The changes in the sextupole component have close to a linear log time dependence, and is felt to be caused by flux creep decay of the magnetization currents in the superconductor filaments. Measurements of this decay have been made under various conditions. The conditions include various central field inductions and changes of field prior to when the decay was measured. The measured field decay in the dipole’s sextupole is proportional to the magnitude and sign of the sextupole due to magnetization which was measured at the start of the decay. This suggests that the decay is a bulk superconductivity flux creep. Proximity coupling appears to play only a minor role in the flux creep according to recent LBL measurements with a stable power supply.
36460570
Progress on the design and fabrication of the mice spectrometer solenoids
The Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling in a short section of a realistic cooling channel using a muon beam at Rutherford Appleton Laboratory (RAL) in the UK. A five-coil, superconducting spectrometer solenoid magnet at each end of the cooling channel will provide a 4 T uniform field region for the scintillating fiber tracker within the magnet bore tubes. The tracker modules are used to measure the muon beam emittance as it enters and exits the cooling channel. The cold mass for the 400 mm warm bore magnet consists of two sections: a three-coil spectrometer magnet and a two-coil matching section that matches the uniform field of the solenoid into the MICE cooling channel. The spectrometer solenoid detailed design and analysis has been completed, and the fabrication of the magnets is well under way. The primary features of the spectrometer solenoid magnet and mechanical designs are presented along with a summary of key fabrication issues and photos of the construction.
136566290
MODELING OF PROXIMITY COUPLING BETWEEN SUPERCONDUCTING FILAMENTS IN SUPERCONDUCTING DIPOLE MAGNETS
There is strong experimental evidence for superconducting current coupling between filaments in fine filament multifilamentary Nb-Ti which has been proposed for the SSC. The coupling between the fine filaments appears to be a Type II superconducting coupling. As a result, a.c. loss and magnetization can increase as one reduces the filament size in a fine filamentary conductor. This paper presents a computer model which fits experimental data for proximity superconducting coupling between filaments in a superconductor matrix. Using this model, one can predict the effect of proximity coupling on the field uniformity of a dipole magnet for the SSC.