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High field solenoids for muon cooling

Description: The proposed cooling system for the muon collider will consist of a 200 meter long line of alternating field straight solenoids interspersed with bent solenoids. The muons are cooled in all directions using a 400 mm long section liquid hydrogen at high field. The muons are accelerated in the forward direction by about 900 mm long, 805 MHz RF cavities in a gradient field that goes from 6 T to -6 T in about 300 mm. The high field section in the channel starts out at an induction of about 2 T in the hydrogen. As the muons proceed down the cooling channel, the induction in the liquid hydrogen section increases to inductions as high as 30 T. The diameter of the liquid hydrogen section starts at 750 mm when the induction is 2 T. As the induction in the cooling section goes up, the diameter of the liquid hydrogen section decreases. When the high field induction is 30 T, the diameter of the liquid hydrogen section is about 80 mm. When the high field solenoid induction is below 8.5 T or 9T, niobium titanium coils are proposed for generating .the magnetic field. Above 8.5 T or 9 T to about 20 T, graded niobium tin and niobium titanium coils would be used at temperatures down to 1.8 K. Above 20 T, a graded bybrid magnet system is proposed, where the high field magnet section (above 20 T) is either a conventional water cooled coil section or a water cooled Bitter type coil. Two types of superconducting coils have been studied. They include; epoxy impregnated intrinsically stable coils, and cable in conduit conductor (CICC) coils with helium in the conduit.
Date: September 8, 1999
Creator: Green, M.A.; Eyssa, Y.; Kenny, S.; Miller, J.R. & Prestemon, S.
Partner: UNT Libraries Government Documents Department

A Four Cell Lattice for the UCLA Compact Light Source Synchrotron

Description: The 1.5 GeV compact light source UCS proposed for UCLA must fit into a shielded vault that is 9.144 meters (30 feet) wide. In order for the machine to fit into the allowable space, the ring circumference must be reduced 36 meters, the circumference of the six cell lattice, to something like 26 or 27 meters. The four cell lattice described in this report has a ring circumference of 27.0 meters.
Date: March 12, 1999
Creator: Garren, A.A. & Green, M.A.
Partner: UNT Libraries Government Documents Department

Tests of a GM Cryocooler and high Tc leads for use on the ALS superbend magnets

Description: A 1.5 W (at the second stage) Gifford McMahon (GM) cryocooler was selected for cooling the superconducting SuperBend dipoles for the Advanced Light Source (ALS) at Berkeley. A GM cryocooler is a reasonable choice if conduction cooled leads are used to provide current to the superconducting magnet. The expected parasitic heat leaks are expected to range from 0.1 to 0.5 W at 4.2 K depending on the temperature of the shield and the cold mass support intercepts. Heat flow to 4 K down the SuperBend 350 A high Tc superconducting leads is expected to vary from 0.11 to 0.35 W depending on the intercept temperature and the current in the leads. The high Tc leads are designed to carry 350 A without significant resistive heating when the upper end of the lead is at 80 K. The 1.5 W cryocooler is expected to provide 45 to 50 W of refrigeration at the first stage at 50 K. The parasitic beat load into the first stage of the cryocooler will be about 8 W. The heat flow from 300 K down the upper copper leads is expected to be around 30 W. The cryocooler and high Tc lead test will measure the penormance of the cryocooler and the high Tc leads. The heat leak down the cryocooler, when it is not operating, is also of interest.
Date: July 9, 1999
Creator: Zbasnik, J.; Green, M.A.; Hoyer, E.H.; Taylor, C.E.; Chen, J.Y. & Wang, S.T.
Partner: UNT Libraries Government Documents Department

Refrigeration options for the Advanced Light Source Superbend Dipole Magnets

Description: The 1.9 GeV Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL) produces photons with a critical energy of about 3.1 kev at each of its thirty-six 1.3 T gradient bending magnets. It is proposed that at three locations around the ring the conventional gradient bending magnets be replaced with superconducting bending magnets with a maximum field of 5.6 T. At the point where the photons are extracted, their critical energy will be about 12 keV. In the beam lines where the SuperBend superconducting magnets are installed, the X ray brightness at 20 keV will be increased over two orders of magnitude. This report describes three different refrigeration options for cooling the three SuperBend dipoles. The cooling options include: (1) liquid helium and liquid nitrogen cryogen cooling using stored liquids, (2) a central helium refrigerator (capacity 70 to 100 W) cooling all of the SuperBend magnets, (3) a Gifford McMahon (GM) cryocooler on each of the dipoles. This paper describes the technical and economic reasons for selecting a small GM cryocooler as the method for cooling the SuperBend dipoles on the LBNL Advanced Light Source.
Date: July 9, 1999
Creator: Green, M.A.; Hoyer, E.H.; Schlueter, R.D.; Taylor, C.E.; Zbasnik, J. & Wang, S.T.
Partner: UNT Libraries Government Documents Department

The design and construction of a gradient solenoid for the high powered RF cavity experiment for the muon collider

Description: This report describes the construction and test of a split solenoid that has a warm bore of 440 mm and a cryostat length of 1088 mm. (A 750 mm section contains the magnetic field.) When the coils are hooked so the fields are additive, the central induction is 5.0 T at its design current. When the coils are hooked so that the fields are in opposition, the induction at the center of the solenoid is zero and the peak induction on the solenoid axis is {+-}3.7 T. The on-axis induction gradient is 25 T per meter when the coils are hooked in opposition. When the coils are operated at their design currents in opposition, the force pushing the two coils apart is about 3 MN. The force pushing the coils apart is carried by the aluminum coil mandrel and a solid aluminum sheath outside of the superconducting winding. The coil was wound as a wet lay-up coil using alumina filled epoxy (Stycast). A layer of hard aluminum wire wound on the outside of the superconducting coil carries some of the hoop forces and limits the strain so that training does not occur. At design current, at both polarities, the peak induction in the windings is about 7 T. This report describes the solenoid magnet system and its construction.
Date: September 5, 1999
Creator: Green, M.A.; Chen, J.Y. & Wang, S.T.
Partner: UNT Libraries Government Documents Department

A design for a combined function superconducting dipole for a muon collider FFAG accelerator

Description: 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 400 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.
Date: September 10, 1999
Creator: Green, M.A.
Partner: UNT Libraries Government Documents Department

Bent solenoid simulations for the muon cooling experiment

Description: The muon collider captures pions using solenoidal fields. The pion are converted to muons as they are bunched in an RF phase rotation system. Solenoids are used to focus the muons as their emitance is reduced during cooling. Bent solenoids are used to sort muons by momentum. This report describes a bent solenoid system that is part of a proposed muon cooling experiment. The superconducting solenoid described in this report consists of a straight solenoid that is 1.8 m long, a bent solenoid that is 1.0 m to 1.3 m long and a second straight solenoid that is 2.6 m long. The bent solenoid bends the muons over an angle of 57.3 degrees (1 radian). The bent solenoid has a minor coil radius (to the center of the coil) that is 0.24 m and a major radius (of the solenoid axis) of 1.0 m. The central induction along the axis is 3.0 T There is a dipole that generates an induction of 0.51 T, perpendicular to the plane of the bend, when the induction on the bent solenoid axis is 3.0 T.
Date: July 9, 1999
Creator: Green, M.A.; Eyssa, Y.M.; Kenney, S.; Miller, J.R. & Prestemon, S.
Partner: UNT Libraries Government Documents Department

Bent Superconducting Solenoids for the Muon Cooling Experiment

Description: This report describes some solenoid design work done for the cooling experiment for the muon collider collaboration. This report describes an analysis section of superconducting solenoids that have a center line induction of 3.0 T. The section is bent in the shape of an S. Each bend in the S bends the muon beam one radian (57.3 degrees). The warm bore diameter of the solenoid bent solenoid is 300 to 320 mm. The radius of the bend at the solenoid center line is 1000 mm. This report shows the results of three dimensional field calculations and presents a solenoid design that will include four TPC detectors that are 240 mm in diameter and 550 mm long as well as a 1300 mm long section of 1300 MHz RF cavities. The TPC sections need a solenoid wann bore diameter of about 300 320 mm while RF cavities require a warm bore diameter of 440 mm. The superconducting solenoid design must take into account the varying warm bore diameter requirements for the magnet string yet meet the stringent solenoidal field uniformity requirements within the active volume of the four TPCs.
Date: March 18, 1999
Creator: Green, M.A.; Eyssa, Y.; Kenney, S.; Miller, J. R.; Prestemon, S. & Wang, S.T.
Partner: UNT Libraries Government Documents Department

Superconducting magnets for muon capture and phase rotation

Description: There are two key systems that must operate efficiently, in order for a muon collider to be a viable option for high energy physics. These systems are the muon production and collection system and the muon cooling system. Both systems require the use of high field superconducting solenoid magnets. This paper describes the supcrconducting solenoid system used for the capture and phase rotation of the pions that are produced on a target in a high intensity proton beam.
Date: July 26, 1999
Creator: Green, M.A. & Weggel, R.J.
Partner: UNT Libraries Government Documents Department

Superconducting solenoids for the Muon collider

Description: The muon collider is a new idea for lepton colliders. The ultimate energy of an electron ring is limited by synchrotron radiation. Mouns, which have a rest mass that is 200 times that of an electron can be stored at much higher energies before synchrotron radiation limits ring performance. The problem with muon is their short lifetime (2.1 microseconds at rest). In order to operate a muon storage ring large numbers of muon must be collected, cooled and accelerated before they decay to an electron and two neutrinos. As we see it now, high field superconducting solenoids are an integral part of a muon coUider muon production and cooling systems. This report will describe the design parameters for superconducting and hybrid solenoids that are used for pion production and collection, RF phase rotations of the pions as they decay into muons and the muon cooling (reduction of the muon emittance) before acceleration.
Date: September 23, 1999
Creator: Green, M.A.; Eyssa, Y.; Kenny, S.; Miller, J.R.; Prestemon, S. & Weggel, R.J.
Partner: UNT Libraries Government Documents Department