mu2e magnet design changes michael lamm for the mu2e collaboration and td/magnet systems dept. march...
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![Page 1: Mu2e Magnet Design Changes Michael Lamm for the Mu2e Collaboration and TD/Magnet Systems Dept. March 26, 2012 All Experimenters Meeting 1 Contributors](https://reader035.vdocuments.mx/reader035/viewer/2022062422/56649f1c5503460f94c3264c/html5/thumbnails/1.jpg)
Mu2e Magnet Design Changes
Michael Lamm
for the Mu2e Collaboration
and TD/Magnet Systems Dept.
March 26, 2012All Experimenters Meeting 1
Contributors to the Mu2e Solenoid Design:
N. Andreev, G. Ambrosio, R. Bossert, J. Brandt, M. Buehler, R. Coleman, D. Evbota, W. Jaskierny, V.V. Kashikhin, M. Lopes, J. Miller, T. Nicol, D. Orris, R. Ostojic, T. Page, T. Peterson, J. Popp, V, Pronskikh, Z. Tang, M. Tartaglia, Z. Tang, M. Wake, R. Wands and R. Yamada
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2
ProductionSolenoid
TransportSolenoid
DetectorSolenoid
ProductionTarget Collimators
StoppingTarget Tracker Calorimeter
protons
2.5T4.6T
2.0T
1.0T
e
Mu2e experiment consists of 3 solenoid systems:
Measure the Rare Process: - + N e- + N
Muon timing is important.Negative axial field gradients prevent unwanted trapped particles from entering “Search Window”
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March 26, 2012All Experimenters Meeting 3
Reason for Design Changes
• Recommendations from May 2011 Independent Design Review
– More operating margin for PS
– Simplify DS
– Better mechanical support for PS coils
• Value Management exercise in Fall 2011– Reduce cost of Solenoid project by ~$20M
• Change in requirements– Field requirements have become less stringent with
detailed beam studies Simplify magnet designs
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L2 Solenoid
Feedboxes
Distribution Lines
TS4-5Cryostat
TS3 Cryostat
TS1-2 Cryostat
DS Cryostat
PS cryostat
• Power Supply/Quench Protection• Cryoplant
PS IRON
DS IRON
• Field Mapping • Ancillary Equipment• Insulating vacuum• Installation and commissioning
• Production Solenoid (PS)• Transport Solenoid (TS)• Detector Solenoid (DS)• Cryogenic Distribution
OFF PROJECT
Single Layer-shorter Spectrometer
4.6 T peak field Less layers for PS
DOWN SCALEDDOWN SCALED
Changes Since May 2011 IDR
4
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PS Baseline Design Changes
All Experimenters Meeting5
Iron Return YokeCryostat Wall
• Peak field 5T- I operation ~10kA• NbTi Rutherford cable + Ni doped
aluminum stabilizer (like ATLAS CS)
• Indirect Cooling (Thermal Siphon)• Hadron absorber intercepts beam
secondaries– ~20 Watts deposited in coils
• Nominal peak field 4.6T– 5T still possible with reduced
margin
• Reduce number of layers• Thinner conductor (lower current)• Remove iron yoke
Gradient made by 3 axial coils same turn density but change # of layers
Wound on individual bobbins
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PS Field vs. Tolerance Bands
All Experimenters Meeting March 26, 2012 6
Meets 5% field uniformity spec
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March 26, 2012All Experimenters Meeting 7
Collaboration with Japan
Fabrication of practice PS coil at Toshiba (4 Layer/8 Turns)
Uses aluminum stabilized NbTi conductor from Hitachi Cable
Coil will be later tested at Fermilab
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New baseline Transport Solenoid
TS1
TS2
TS4
TS5
•ThreeTwo cryostats: TSU, TSD
•TS3: TS3U, TS3D. Wider coils to compensate for gap
Rotatable Collimator, P-bar window
G. AmbrosioTS Leader
•New coil fabrication proposed for better mechanical support.
All Experimenters Meeting March 26, 2012 8
•TS1,TS3,TS5: Straight sections with axial gradient•TS2/TS4: approximate toroidal field•Accomplished by many thin solenoid rings of different amp-turns
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Coil Fabrication
9
Bolted connections
Conductor
Al Outer Supports
March 26, 2012
• Original plan: use SS inner bobbins mechanical support complications.
• New plan: fabrication unit consists of two coils with outer support aluminum structure
• Coils wound on collapsible mandrel-then fit into outer aluminum ring
• Placement of coil in transport is determined by outer shell geometry
All Experimenters Meeting
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TS Field Requirements
• All sections meet all requirements• Large margin wrt gradient requirement
March 26, 2012All Experimenters Meeting 10
Axial field distribution in the center of TS3 (left), axial gradient along TS3 (right).
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Simplify DS Baseline
March 26, 2012
• OLD base line– Two coils: gradient + spectrometer bussed in series in a single cryostat– Two layer spectrometer, single mandrel field uniformity – Two layer gradient on single mandrel with aluminum spacers– Iron return yoke (not shown)
11All Experimenters Meeting
Spectrometer SectionGradient Section
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Simplify DS Baseline
March 26, 2012
Spectrometer Section
Gradient Section
• New base line driven by relaxed field requirements– Modular coil design reduced cost/coil
– Spectrometer: 3 Single Layer Coils shorter coils, greatly reduced conductor volume, reduced field uniformity OK
– Original conductor cost estimate based on expensive PS conductor, smaller field DS requires smaller cross section, no need for special reinforced aluminum
– Relaxed calorimeter field requirements shorten spectrometer
12All Experimenters Meeting
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DS Field vs. Tolerance Bands
March 26, 2012 13All Experimenters Meeting
Gradient Section Spectrometer Section
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March 26, 2012All Experimenters Meeting 14
Conclusion
• Significant amount of work done prior to CD1– Conceptual design of solenoids
– Technology development with Japan
• Near term schedule– CD1 directors review April 3-5, Lehman review in June
– June 2012-2014• Test Toshiba coil/built prototype TS module/prototype conductor
– CD2 sometime in 2014• Order conductor/ Contract final design with industry
– Begin fabrication in 2016