121120579
The two-coil toroid magnet, an option for ASTROMAG
The ASTROMAG particle astrophysics experiment for the US space station requires a magnetic field in order to determine the energy and momentum of charged particles of various momenta. A second concept for generating magnetic field for ASTROMAG is presented. This magnet configuration consists of two D-shaped coils which form a two-coil toroid. The two coils are located within a paddle connected to a spherical helium tank. The physics detectors would be located on either side of the flat paddle. The particles travel toward the tank in a direction approximately parallel to the paddle surface. A description is given of the two-coil toroid, the magnet cryostat, and the helium II cryogenic system, which keeps the magnet cold for up to two years without refilling. >
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
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.
94844521
ACTIVE CENTER TAP QUENCH PROTECTION
122496955
Anomaly-free chiral theories in six dimensions
Abstract The coupled N = 1 Yang-Mills plus supergravity theory in ten dimensions can be made anomaly-free for SO(32) or E 8 × E 8 . Only the case of SO(32) is known to correspond to a superstring theory, which is probably necessary for a fully consistent quantum theory. Anomaly-free chiral theories in lower dimensions can be obtained by considering nontrivial compactifications (involving nonzero background gauge fields) of the ten-dimensional theory that satisfy a topological consistency condition. This paper considers the compactification of four dimensions on the manifold K 3 without requiring that the equations of motion be satisfied. This leads to a large number of anomaly-free chiral supersymmetric six-dimensional theories, corresponding to various ways of embedding U(1) factors in SO(32) or E 8 × E 8 .
14198728
Two loops in eleven-dimensions
The two-loop Feynman diagram contribution to the four-graviton amplitude of eleven-dimensional supergravity compactified on a two-torus, T^2, is analyzed in detail. The Schwinger parameter integrations are re-expressed as integration over the moduli space of a second torus, \hat T^2, which enables the leading low-momentum contribution to be evaluated in terms of maps of \hat T^2 into T^2. The ultraviolet divergences associated with boundaries of moduli space are regularized in a manner that is consistent with the expected duality symmetries of string theory. This leads to an exact expression for terms of order D^4 R^4 in the effective M theory action (where R^4 denotes a contraction of four Weyl tensors), thereby extending earlier results for the R^4 term that were based on the one-loop eleven-dimensional amplitude. Precise agreement is found with terms in type IIA and IIB superstring theory that arise from the low energy expansion of the tree-level and one-loop string amplitudes and predictions are made for the coefficients of certain two-loop string theory terms as well as for an infinite set of D-instanton contributions. The contribution at the next order in the derivative expansion, D^6 R^4, is problematic, which may indicate that it mixes with higher-loop effects in eleven-dimensional supergravity.
121804056
A lattice formulation of the Reggeon Field Theory and its critical behaviour
Abstract We formulate a lattice description of the Reggeon Field Theory in terms of two-dimensional vector spins of unit length (as in the x − y model). We exhibit, within the context of mean field theory, the phase transition of the Reggeon Field Theory that occurs as the (imaginary) magnetic field and temperature are varied in our statistical mechanical model.
121009179
Strings and Superstrings
The last Nobel Symposium on elementary particle physics ended on May 25 1968. The main topics discussed at that meeting were: high energy scattering of hadrons, infinite component field theory and electroweak unification. The last of these topics is the one which is best remembered since it is associated with the revolution in our understanding of the field theoretic description of the weak and electromagnetic forces. The first two topics, however, are closely associated with the origins of string theory. This talk will survey the development of string theory from that time up to the summer of 1984, since when there has been an explosion of activity in superstring theory which forms the main topic of this meeting.
120850184
Dynamically based coupling scheme for the Pomeranchukon