54934463
QUENCH PROTECTION AND DESIGN OF LARGE HIGH CURRENT DENSITY SUPERCONDUCTING MAGNETS
LBL-12233 m Lawrence Berkeley Laboratory UNIVERSITY OF CALIFORNIA Engineering & Technical Services Division To b e p r e s e n t e d a t t h e 7 t h I n t e r n a t i o n a l C o n f e r e n c e on Magnet T e c h n o l o g y , K a r l s r u h e , West G e r m a n y , March 3 0 - A p r l l 3 , 1 9 8 1 ; a n d t o be p u b l i s h e d in t h e P r o c e e d i n g s QUENCH PROTECTION ..ND DESIGN OF LARGE HIGH- CURRENT-DENSITY SUPERCONDUCTING MAGNETS M.A. March Green MASTER Prepared for the U.S. Department of Energy under Contract W-7405-ENG-48 LIMITED
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. >
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.
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.
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
94844521
ACTIVE CENTER TAP QUENCH PROTECTION
120391337
Dynamical point-like structure and dual strings
Abstract The emission of zero momentum scalar particles into the vacuum from dual strings is shown to be equivalent to the insertion of point-like energy densities on the strings. This suggests a physically plausible procedure for modifying the dual model to incorporate point-like structure leading, for example, to power behaved large angle elastic scattering.
177255
Nondecoupling of maximal supergravity from the superstring.
We consider the conditions necessary for obtaining perturbative maximal supergravity in d dimensions as a decoupling limit of type II superstring theory compactified on a (10-d) torus. For dimensions d=2 and d=3, it is possible to define a limit in which the only finite-mass states are the 256 massless states of maximal supergravity. However, in dimensions d>or=4, there are infinite towers of additional massless and finite-mass states. These correspond to Kaluza-Klein charges, wound strings, Kaluza-Klein monopoles, or branes wrapping around cycles of the toroidal extra dimensions. We conclude that perturbative supergravity cannot be decoupled from string theory in dimensions>or=4. In particular, we conjecture that pure N=8 supergravity in four dimensions is in the Swampland.
120775832
World-sheet dynamics of bosonic string theory
Abstract Bosonic string theory may emerge as an approximation to a two-dimensional string theory in which strings replace the usual pointlike world-sheet fields. In this context the energy of the ground state of the bosonic string (the mass of the tachyon) is shown to arise from the breaking of Atkin-Lehner symmetry on a cylindrical target space. No normal ordering infinities are encountered.
123010874
Production of the new resonances in hadronic collisions
SummaryThe variation with energy and with Feynman’s variablex of the production of ψ and ψ’ is a sensitive test of their production mechanism. A simple parton model predicts that at relatively low energies production nearx=0 is strongly favoured and that the invariant crosssection atx=0 increases by two orders of magnitude between BNL and ISR energies. A sharp increase is also predicted for the ratio of ψ or ψ’ production to the nonresonant lepton pair background.RiassuntoLa variazione della produzione di ψ e ψ’ con l’energia e con la variabilex di Feynman è un test sensibile del loro meccanismo di produzione. Un semplice modello a partoni predice che ad energie relativamente basse la produzione pressox=0 è fortemente favorita e che la sezione d’urto adx=0 aumenta di due ordini di grandezza fra la energia del BNL e quella degli ISR. Si predice anche un netto incremento per il rapporto tra la produzione di ψ o ψ’ e il fondo di coppie leptoniche non risonante.
17427764
A Curious Truncation of N=4 Yang-Mills
The coupling constant dependence of correlation functions of BPS operators in N=4 Yang-Mills can be expressed in terms of integrated correlation functions. We approximate these integrated correlators by using a truncated OPE expansion. This leads to differential equations for the coupling dependence. When applied to a particular sixteen point correlator, the coupling dependence we find agrees with the corresponding amplitude computed via the AdS/CFT correspondence. We conjecture that this truncation becomes exact in the large N and large ’t Hooft coupling limit.