31561398
Superconducting dipoles and quadrupoles for a 2 TeV muon collider
At 2 TeV the mean lifetime for a muon is 41.6 ms. In order to achieve high luminosity at the collider collision point, the dipole central induction for the storage ring should be over 8 T. The storage ring carries muon over 1000 turns through the ring before they decay away. Muons decay to two neutrinos and an electron or positron (depending on the charge of the decaying muon). Seventy percent of the muon energy will be taken away by the neutrinos. The electrons (at average energies of 700 GeV) and the photons (at energies up to 2.1 GeV) are quite penetrating. At the design luminosity of the muon collider, the superconducting dipoles and quadrupoles in the storage ring must contain muon beams (up to 1.4/spl times/10/sup 14/ muons per second) that will deposit over 1.8 kW per meter of energy into the storage ring. This report presents two design approaches for superconducting dipoles and quadrupoles that can be used for the muon collider storage ring.
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. >
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
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.
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.
119238279
Modular properties of two-loop maximal supergravity and connections with string theory
The low-momentum expansion of the two-loop four-graviton scattering amplitude in eleven-dimensional supergravity compactified on a circle and a two-torus is considered up to terms of order S6 4 (where S is a Mandelstam invariant and is the linearized Weyl curvature). In the case of the toroidal compactification the coefficient of each term in the low energy expansion is generically a sum of a number of SL(2, )-invariant functions of the complex structure of the torus. Each such function satisfies a separate Poisson equation on moduli space with particular source terms that are bilinear in coefficients of lower order terms, consistent with qualitative arguments based on supersymmetry. Comparison is made with the low-energy expansion of type II string theories in ten and nine dimensions. Although the detailed behaviour of the string amplitude is not generally expected to be reproduced by supergravity perturbation theory to all orders, for the terms considered here we find agreement with direct results from string perturbation theory. These results point to a fascinating pattern of interrelated Poisson equations for the IIB coefficients at higher orders in the momentum expansion which may have a significance beyond the particular methods by which they were motivated.
120518388
THE QUANTUM MECHANICS OF AN N=1 SUPERPARTICLE IN AN EXTENDED SUPERSPACE
A new ten-dimensional superparticle action with local symmetries implemented via gauge fields is formulated in a superspace with an extra anticommuting space-time spinor coordinate. Light-cone quantization gives the spectrum of N=1 super-Yang-Mills. Covariant gauge choices in which the gauge fields are set to constants lead to free BRST-invariant quantum actions. Possible ghost systems include one with only a finite number of ghosts and several with an infinite number. In each case, the BRST cohomology class of zero ghost number gives the spectrum of N=1 super-Yang-Mills.
120397444
The inclusion of fermions in dual N-point functions
Abstract Dual amplitudes of the five-point function for two fermions and three scalar bosons are constructed, and are used to obtain a consistent procedure for inclusing two fermions in the general N -point function.
122187455
Superfield theory of type (II) superstrings
Abstract Type (II) superstrings are described by light-cone superfields that are functionals of string superspace coordinates x i ( σ ) and ϑ a ( σ ) or the conjugate momenta p i ( σ ) and λ a ( σ ). The interaction hamiltonian and supersymmetry charges are determined to first order in the coupling constant by requiring invariance under the super-Poincare algebra, some of whose generators are implemented locally in σ. In a suitable low-energy limit the formalism goes smoothly into that of extended supergravity in ten dimensions.
122251395
Average properties of dual resonances
Abstract As a consequence of the strong interaction (A.F.S.) scaling of dual amplitudes, we find that the average total width of a high mass resonance approaches a constant which is less than 1/π(GeV) 2 . We also obtain a logarithmic increase of the average multiplicity coming from the decay of dual resonances.