Title: The Design and Construction of the MICE Spectrometer Solenoids
Abstract: IEEE Transactions on Applied Superconductivity 19, No. 3 MICE Note 236 The Design and Construction of the MICE Spectrometer Solenoids Bert Wang Member IEEE, Bob Wahrer, Clyde Taylor, L. Xu, J.Y. Chen, M. Wang, Tiki Juang, Michael S. Zisman, Steve P. Virostek, and Michael A. Green Member IEEE MICE collaboration, the task of fabricating of the spectrometer magnets fell to the Lawrence Berkeley National Laboratory (LBNL). The LBNL design is based on the use of a Nb-Ti superconductor with a copper to superconductor ratio of four [5]. The LBNL magnet is designed to be cooled using three 1.5 W pulse tube coolers. II. M AGNET DESIGN The magnet design parameters are shown in Table I. In Table I, Z1 and Z2 are the axial distances from the match coil end of the cold mass to the two ends of the coil. The coil length is Z2 - Z1. R1 is the coil inner radius; R2 is the coil outer radius. The coil thickness is R2 - R1. T ABLE I. T HE S PECTROMETER M AGNET C OIL P ARAMETERS Parameter No. Turns/Layer No. of Layers Total Turns Z1 (mm) Z2 (mm) R1 (mm) R2 (mm) Delta Z (mm) Delta R (mm) Abstract— The purpose of the MICE spectrometer solenoid is to provide a uniform field for a scintillating fiber tracker. The uniform field is produced by a long center coil and two short end coils. Together, they produce 4T field with a uniformity of better than 1% over a detector region of 1000 mm long and 300 mm in diameter. Throughout most of the detector region, the field uniformity is better than 0.3%. In addition to the uniform field coils, we have two match coils. These two coils can be independently adjusted to match uniform field region to the focusing coil field. The coil package length is 2544 mm. We present the spectrometer solenoid cold mass design, the powering and quench protection circuits, and the cryogenic cooling system based on using three cryocoolers with re-condensers. Index Terms— Magnet Design, Magnet Fabrication, and Magnet Cooling I. I NTRODUCTION M1 M2 E1 C E2 T HE key accelerating and storing muon beams is muon beam cooling [1]. Muon beam cooling will be demonstrated by the Muon Ionization Cooling Experiment (MICE) at the Rutherford Appleton Laboratory in the UK [2]. The cooling channel for MICE consists of three types of solenoid magnets; 1) the three focusing magnets that are around the liquid hydrogen absorbers [3], 2) the two coupling magnets that surround the RF cavities that re-accelerate the muons to restore their longitudinal momentum [4], and 3) the two spectrometer magnets that are used to analyze the muon beams entering and leaving the cooling channel [5]. Each spectrometer magnet consists of two match coils M1 and M2 and three-coil spectrometer section (E1, C and E2). M1 and M2 are used to match the spectrometer section with the MICE channel. The three-coil section produces a uniform magnetic field (±0.3 percent) within a region that is 1.0-m long and 0.3-m in diameter. The uniform field section contains a five-plane scintillating fiber detector for muon beam emittance analysis. The spectrometer solenoid design is based on a design made by INFN Genoa [6]. When INFN Genoa dropped out of the Manuscript received 26 August 2008. This work was supported by the Office of Science US Department of Energy under DOE contract DE-AC02- 05CH11231. DOE funding for the US Neutrino Factory Muon Collider Collaboration is greatly appreciated. S. T. Wang, C. Taylor, X. Lu, J, Y. Chen, M. Wang, and T. Juang are with Wang NMR, Livermore CA, USA 94550. E-mail [email protected]. M. S. Zisman, S. P. Virostek and M. A. Green, are with the Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. The corresponding author is M. A. Green with LBNL. Phone +1-510-486-5598, Fax +1-510-486-6668, and e-mail: [email protected]). The bobbin for the five coils is machined from a single forged 6061-T6-aluminum cylinder (see Fig. 1) to contain the magnet axial load. The magnet radial load is supported by the conductor in the coil and aluminum band of 6 to 10 mm in thickness. Coil winding is shown in Fig 2. The magnet after winding and banding is shown in Fig. 3. Fig. 1. The Magnet Forged 6061-T6 Mandrel during Machining.
Publication Year: 2009
Publication Date: 2009-02-27
Language: en
Type: article
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