119447674
Configurations of two D-instantons
Abstract The potential between two separated D-instantons at fixed (super) space-time points is obtained by a simple explicit integration over the ‘massive’ variables of the zero-dimensional reduction of ten-dimensional U (2) super Yang-Mills theory. This potential vanishes for asymptotically large separations, becoming significant at separations of around the ten-dimensional Planck scale with a singularity at the origin, which is resolved by the extra ‘massless’ internal Yang-Mills super-coordinates.
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.
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.
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.
122379741
The UCLA Phi Factory Detector, the Integration of Superconducting Compensation Solenoids and the Final Focus Interaction Region Quadrupoles
Abstract The proposed Phi Factory for the University of California at Los Angeles (UCLA) is a small 510 MeV electron-positron colliding beam storage ring with high luminosity (greater than 10 32 cm −2 s −1 ). In order to do high quality Phi physics, a particle detector system with a large solid angle (preferably greater than 98 percent) is required. Particle detection and analysis will be done within a 0.5 tesla solenoidal magnetic field. The solenoidal field within the detector causes coupling between beam oscillations in the horizontal and vertical directions. Therefore, compensation solenoids are required to keep the circulating particle beams from seeing the effects of the field from the main detector solenoid. Since high luminosity and a large solid angle are required, the detectors and a pair of compensation solenoids must be integrated with the final focus quadrupoles within the detector straight section. This report describes the design of two tapered, 0.5 tesla, superconducting compensation solenoids which must go around six rare earth permanent final focus quadrupoles or six superconducting quadrupoles on either side of the beam collision point. A cryogenic cooling system for these two solenoids, which will be coupled with the cooling system for the primary detector solenoid, is also described.
122023958
Tests on large diameter superconducting solenoids designed for colliding beam accelerators
Two prototype large diameter thin coil solenoids which use the mechanical structure to moderate quenches, have been built and systematically tested. The solenoids are cooled by two phase helium flowing in tubes which form a part of the coil structure. The coils have been tested by inducing a series of quenches at various currents. The results of these tests are given in this paper.
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.
29897332
High-gradient normal-conducting RF structures for muon cooling channels
We present a status report on the research and development of high-gradient normal-conducting RF structures for the ionization cooling of rations in a neutrino factory or muon collider. High-gradient RF structures are required in regions enclosed in strong focussing solenoidal magnets, precluding the application of superconducting RF technology. We propose using linear accelerating structures, with individual cells electromagnetically isolated, to achieve the required gradients of over 15 MV/m at 201 MHz and 30 MV/m at 805 MHz. Each cell will be powered independently, and cell length and drive phase adjusted to optimise shunt impedance of the assembled structure. This efficient design allows for relatively small field enhancement on the structure walls, and an accelerating field approximately 1.7 times greater than the peak surface field. The electromagnetic boundary of each cell may be provided by a thin Be sheet, or an assembly of thin-walled metal tubes. Use of thin, low-Z materials will allow passage of the muon beams without significant deterioration in beam quality due to scattering. R&D in design and analysis of robust structures that will operate under large electric and magnetic fields and RF current heating are discussed, including the experimental program based in a high-power test laboratory developed for this purpose.
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].