1. 1 The Genoa Tracker Solenoids and their Contribution toward a New Design Michael A. Green Lawrence Berkeley National Laboratory and Pasquale Fabbricatore INFN Genoa 27 June 2005

2. 2 INFN Genoa Tracker Magnet Design

3. 3 The Genoa Tracker Solenoid Iron Shield End Coil 2 End Coil 1 Center Coil Match Coil 1 4.2 K Cooler Cold Mass Support Match Coil 2 He Cooling Pipe Radiation Shield Al Coil Spacer

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6. 6 INFN Tracker Magnet Parameters This table has not changed since October of 2004. The inductance of the three spectrometer coils in series is 92 H. The stored energy of the Three spectrometer coils at 258 A is about 3.06 MJ.

7. 7 A New LBNL Tracker Magnet Based on the INFN Genoa Magnet

8. 8 Moving toward a New Tracker Solenoid Design The LBNL tracker solenoid design is based on the INFN Genoa design, except that it will use the same Nb-Ti conductor that will be used for the focusing and coupling solenoids. As a result, the coil current densities will be similar to the MICE focusing coils. The LBNL magnet warm bore, cryostat length, and the cryostat outer diameter are the same as the INFN Genoa design. In terms of integrating the trackers, the iron shield, and the radiation shield with the solenoid, there is no real change.

9. 9 The New Tracker Magnet Superconductor

10. 10 INFN Tracker with a Mandrel

11. 11 MICE Superconductor Specification Conductor Length = 130000 m Conductor Size = 1.00 x 1.65 mm* Corner Radius = 0.2 < 0.475 mm Formvar Insulation Average Thickness = ~0.025 mm* Cu to S/C Ratio = 4.0 ± 0.3 Copper RRR = >100 @ 10 K Filament Diameter = < 80  m Number of Filaments = 50 < 500 Filament Spacing = >8  m Conductor n value = > 35 Nb-Ti Twist Pitch = 13 ± 1.5 mm I c (5 T,4.2 K) ≥ 760 A The Lab G magnet conductor shown above is an acceptable conductor. The conductor specification will go to several vendors in the US, Europe, and Japan for a quote. * With Formvar Insulation

12. 12 The Conductor Drives the New Magnet Design

13. 13 Changes in the Tracker Magnet Design that Result from the Conductor The average coil current density goes up by over a factor of two. This means that quench back must be used for quench protection. The coils will be thinner, because the number of turns per coil is approximately the same. The temperature margin for the INFN and LBNL tracker solenoids is nearly the same even though the conductor current density is higher. The conductor cost should be lower (by a factor of over 2) and the cost of winding the conductor is also lower (by a factor of 1.3 to 1.4).

14. 14 LBNL Tracker Magnet Parameters Design A (Same Inner R Coils) The inductance of the three spectrometer coils in series is 75 H. The stored energy of the Three spectrometer coils at 258 A is about 2.51 MJ. The currents shown in the table are based on the most recent optimization of MICE. The coil currents may change a few percent if MICE is re-optimized for the new magnets. Superconductor Length = 55000 meters per Magnet Center Coil is Longer

15. 15 LBNL Tracker Magnet Parameters Design B (Same Average R Coils) The inductance of the three spectrometer coils in series is 92 H. The stored energy of the Three spectrometer coils at 258 A is about 3.06 MJ. Superconductor Length = 61000 meters per Magnet The currents shown in the table are based on the most recent optimization of MICE. The coil currents are not expected to change, if MICE is re-optimized.

16. 16 New Magnet Coil Temperature Margins

17. 17 Other Tracker Magnet Changes The LBNL magnet will be wound on an aluminum mandrel. The INFN magnet design has separately wound and potted coils with aluminum spacers. The LBNL magnet has a helium tank on the outside of the coils. The INFN magnet is cooled with helium in tubes that around the superconducting coils. The LBNL design will have a lower  T from the coils to the cooler cold head. The LBNL center coil will quench fully in < 2 sec using quench back. The INFN center coil takes much longer to quench fully without quench back.

18. 18 Tracker Magnet Power System

19. 19 LBNL Tracker Magnet Schedule and Cost The order for the conductor for both magnets will tendered before October 2005 Magnet Engineering should start in early 2006. The first tracker solenoid should be tested in the fall of 2007. Delivery of the magnet to RAL should occur in early 2008. The second tracker solenoid should be tested in the spring of 2008. Delivery of the magnet to RAL should occur in the middle of 2008. The cost of both tracker magnets including LBNL engineering & overhead should be about 2.0 M$.

20. 20 Concluding Comments The magnet work by INFN Genoa has provided the framework upon which the new tracker magnet parameters have been developed. The LBNL tracker magnet design does not change the tracker design, the iron shield design or the radiation shield design. The LBNL tracker solenoid uses a higher current density conductor. As a result, a number of coil design changes have been made. LBNL can provide both tracker solenoids for MICE by August 2008, provided there is adequate funding.