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
24392991
The Engineering Design of the 1.5 m Diameter Solenoid for the MICE RFCC Modules
The RF coupling coil (RFCC) module of MICE is where muons that have been cooled within the MICE absorber focus (AFC) modules are re-accelerated to their original longitudinal momentum. The RFCC module consists of four 201.25 MHz RF cavities in a 1.4 meter diameter vacuum vessel. The muons are kept within the RF cavities by the magnetic field generated by a superconducting coupling solenoid that goes around the RF cavities. The coupling solenoid will be cooled using a pair of 4 K pulse tube cooler that will generate 1.5 W of cooling at 4.2 K. The magnet will be powered using a 300 A two-quadrant power supply. This report describes the ICST engineering design of the coupling solenoid for MICE.
94844521
ACTIVE CENTER TAP QUENCH PROTECTION
118834673
A Design for a Combined Function Superconducting Dipole for a Muon Collider FFAG Accelerator
The acceleration stages for a muon collider require that the muons be accelerated within a given ring in fewer than twenty turns. One type of accelerator that appears to be attractive for a synchrotron that accelerates the muon a factor of four in energy in a few turns is the Fixed Field Alternating Gradient (FFAG) type of accelerator. As the energy of the muon beam increases, the muons move toward a higher field region of a DC combined function dipole. The following dipole and quadrupole magnet characteristics are required for a muon FFAG machine to be successful: (1) The dipole will be a fixed field dipole with an impressed quadrupole and sextupole field. There may or may not be separate quadrupoles that mayor may not have added sextupole windings. (2) The horizontal aperture of the required good field region is wider than the vertical aperture of the required good field region. (3) The magnet is relatively short, so that the conventional SSC type of superconducting dipole or quadrupole ends can not be used. The field at the end of the magnet must fall off abruptly within the distance of less than one vertical aperture. For a magnet that is 400more » mm long, the end region can be no more than 80 mm long. (4) The structure of the integrated field within the end region must be the same as the structure of the two-dimensional filed at the center of the magnet. A very preliminary design concept for a FFAG combined function dipole is presented in this paper.« less
123081787
PROGRESS ON THE SUPERCONDUCTING MAGNET FOR THE TIME PROJECTION CHAMBER EXPERIMENT (TPC) AT PEP
The TPC (Time Projection Chamber) experiment at PEP will have a two meter inside diameter superconducting magnet which creatests a 1.5 T uniform solenoidal field for the TPC. The superconducting magnet coil, cryostat, cooling system, and the TPC gas pressure vessel (which operatests at 11 atm) were designed to be about two thirds of a radiation length thick. As a result, a high current density coil design was chosen. The magnet is cooled by forced flow two phase helium. The TPC magnet is the largest adiabatically stable superconducting magnet built to date. The paper presents the parameters of the TPC thin solenoid and its subsystems. Tests results from the Spring 1980 cryogenic tes are presented. The topics to be dealt with in the paper are cryogenic services and the tests of magnet subsystems such as the folded current leads. Large thin superconducting magnet technology will be important to large detectors to be used on LEP.
122748175
Calculation of the pressure rise in the cooling tube of a two-phase cooling system during a quench of an indirectly cooled superconducting magnet
Large superconducting detector magnets are indirectly cooled with two-phase helium flowing in cooling tubes attached to the coil or its support structure. Large detector magnets often quench such that most of the magnet stored energy ends up as heat stored in the coil package. The time constant for energy deposition in the coil and support structure is often quite short. This paper presents a method for calculating the peak pressure rise in the magnet two-phase cooling tube during a magnet quench. A comparison of calculated peak pressure rise and measured pressure rise for the PEP-4 solenoid is presented in this report. >
15249184
Boundary Effects in String Theory
Some of the properties of string theory defined on world-sheets with boundaries are reviewed. Particular emphasis is put on the possibility of identifying string configurations (\lq D-instantons' and \lq D-branes') that give rise to stringy non-perturbative effects.
119898581
Space-time duality and Dirichlet string theory
Abstract Bosonic open-string theory (with Neumann boundary conditions) compactified on a torus is related by spatial duality to a theory living on the dual torus and satisfying constant (Dirichlet) boundary conditions. Amplitudes are functions of the “positions” of the Dirichlet boundaries. A Minkowski-space Dirichlet string theory may be defined by summing insertions of zero-momentum Dirichlet boundaries in orientable world-sheets of arbitrary genus. This is a closed-string theory with a radically altered vacuum state, in which fixed-angle scattering is power behaved as a function of energy.
122955461
The structure of superstring field theories
Abstract Superstring field theories involve two basic types of local interactions, which may be regarded as string generalizations of a cubic Yang-Mills coupling and a cubic gravity coupling. The higher-order contact terms of the low-energy effective supergravity field theories arise from the exchange of massive superstring states.
120192541
Discrete and Abelian lattice gauge theories
Gauge-invariant discrete and Abelian (X-Y) spin models with compact degrees of freedom are studied in (D + 1) Euclidean (“space-time”) dimensions (D ⩽ 3). They are formulated in terms of quantum Hamiltonians on a D-dimensional spatial lattice. In this approach the periodic Gaussian and Abelian models are identical. 
 
Duality transformations are obtained which relate the topological excitations of one model to the fundamental quantum spin excitations of another. These motivate the extension of the usual gauge-invariant structure to “gauge invariance of the third kind” which involves degrees of freedom associated with the surfaces of the plaquettes. 
 
The nature of the excited states and the behaviour of the order (and disorder) parameters are discussed in various limits of the coupling constants. For both discrete and Abelian theories the behaviour of the order parameter (the Wilson loop) depends crucially on whether the spins in the theory carry the fundamental unit of charge or a multiple of it.
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.