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

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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

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INFN Genoa TrackerMagnet Design

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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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5

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INFN Tracker Magnet Parameters

Parameter Match 1 Match 2 End 1 Center End 2

Z distance from MICE Center* (mm) 3510 3951 4391 4571 5891

Coil Length (mm) 202 202 120 1260 120

Coil Inner Radius (mm) 255 255 255 255 255

Coil Thickness (mm) 100 57 138 50 149

Number of Layers 60 34 82 30 90

Number of Turns per Layer 84 84 50 525 50

Coil Overall Current Density (A mm -2) 66.82 73.25 61.59 64.44 67.11

Coil Current (A) 267.8 293.8 248.8 257.8 266.7

Coil Self Inductance (H) 15.9 5.0 12.6* 47.0* 15.1*

Peak Induction in the Coil (T) 4.8 3.8 4.9 4.0 5.2

Coil Stored Energy at Current above (MJ) 0.57 0.22 0.39 1.56 0.54

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 theThree spectrometer coils at 258 A is about 3.06 MJ.

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A New LBNL Tracker MagnetBased on the INFN Genoa Magnet

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Moving toward a New TrackerSolenoid 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.

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The New TrackerMagnet Superconductor

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INFN Tracker with a Mandrel

230 mm

~2750 mm

End Coil #1, L = 120 mm t = 138 mm

Lead and Cooler Neck

End Coil #2, L = 120 mm, t = 149 mm

Matching Coil #1, L = 202 mm, t = 100 mm

Matching Coil #2, L = 202 mm t = 57 mm

40 K Shield

4T Good Field Region

0.3 m Φ , 1.0 m L

, = 1260 , = 50 Center Coil L mm t mm

200 mm

~460 mm255 mm 240 mm

238 mm

60 mm Spacer

60 mm Spacer

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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• Ic(5 T,4.2 K) ≥ 760 A

1.00 mm1.65 mm0.95 mm1.60 mmFormvar Insulation

The Lab G magnet conductor shownabove is an acceptable conductor.

The conductor specification will go to several vendors in the US, Europe, and Japan for a quote. * With Formvar Insulation

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The Conductor Drives theNew Magnet Design

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Changes in the Tracker Magnet Designthat 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).

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LBNL Tracker Magnet ParametersDesign A (Same Inner R Coils)

Parameter Match 1 Match 2 End 1 Center End 2Z distance from MICE Center* (mm) 3512 3953 4391 4554 5891Coil Length (mm) 198 197 121 1294 121Coil Inner Radius (mm) 255 255 255 255 255Coil Thickness (mm) 46.2 26.4 61.6 22.0 68.2Number of Layers 42 24 56 20 62Number of Turns per Layer 120 119 73 784 73Coil Overall Current Density (A mm-2) 147.55 161.34 136.84 142.60 145.44Coil Current (A) 267.8 293.8 249.5 258.9 265.2Coil Self Inductance (H) 12.8 4.3 9.4* 40.5* 11.1*Peak Induction in the Coil (T) 4.8 3.8 4.9 4.0 5.2Coil Stored Energy at Current above (MJ) 0.46 0.19 0.29 1.36 0.39

The inductance of the three spectrometer coils in series is 75 H. The stored energy of theThree 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

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LBNL Tracker Magnet ParametersDesign B (Same Average R Coils)

Parameter Match 1 Match 2 End 1 Center End 2Z distance from MICE Center* (mm) 3512 3953 4391 4554 5891Coil Length (mm) 198 197 121 1294 121Coil Inner Radius (mm) 281.9 270.3 293.2 269.2 295.4Coil Thickness (mm) 46.2 26.4 61.6 22.0 68.2Number of Layers 42 24 56 20 62Number of Turns per Layer 120 119 73 784 73Coil Overall Current Density (A mm-2) 147.55 161.34 136.84 142.60 145.44Coil Current (A) 267.8 293.8 249.5 258.9 265.2Coil Self Inductance (H) 15.9 5.0 12.6* 47.0* 15.1*Peak Induction in the Coil (T) 4.8 3.8 4.9 4.0 5.2Coil Stored Energy at Current above (MJ) 0.57 0.22 0.39 1.56 0.54

The inductance of the three spectrometer coils in series is 92 H. The stored energy of theThree 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.

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New Magnet Coil Temperature Margins

1098765432100

50

100

150

200

250

300

350

400

450

500

T = 3.4 KT = 4.2 KT = 5.0 KTracker M1Tracker M2Tracker E1Tracker CTracker E2

Magnetic Induction at the Conductor (T)

Conductor Current (A)

Tracker M1 Margin = 2.0 KTracker M2 Margin = 2.5 KTracker E1 Margin = 1.9 KTracker C Margin = 2.3 KTracker E2 Margin = 1.7 K

Conductor Ic Versus B

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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.

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Tracker Magnet Power System

Power Supply±10 V, 300 A

Power Supply±10 V, 50 A

PSPSPSPSPSPSPSPower Supply±10 V, 50 A

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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$.

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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.