Post on 18-Jan-2016
TD Designs for mu2e Solenoid Magnets
Michael Lamm
for the Mu2e Collaboration
and TD/Magnet Systems Dept.
All Experimenters’ Meeting
January 25, 2010
January 25, 2010All Experimentors Meeting 2
What is Mu2e?• Measure the Rare Process: - + N e- + N relative to
- + N(A,Z) + N(A, X) – Goal: 4 orders of magnitude increase in sensitivity over previous
experiments• Strategy:
– Stopped muons in aluminum atom: high probability of interaction • Significant overlap of muon and nucleus wave functions
– Kinematically constrained - + N e- + N produces mono-energetic electrons
– Use lifetime of muon in atom to suppress “prompt backgrounds”• Out of time pions, p-bars, electrons in muon channel are a serious
problem
• Magnets role in Mu2e– Transport as many in-time, stoppable muons as possible– Prevent out of time other particles from reaching stopping target– Provide a uniform stable field for the final captured electron
spectrometer
January 25, 2010All Experimentors Meeting 3
Magnet System by Function
12206
25687
•Production Solenoid
8 GeV P•Transport Solenoid
•Graded field to collect conv. e- (2T1T)
•Uniform field for e- Spectrometer (1T)
e- Spectrometer
Production Target (PT) Central Collimator (CC) Stopping Target (ST)
ST
PT
CC
• Reflect and focus low P /’s into muon transport
• Strong Axial Gradient Solenoid Field 5T2.5T
•Sign/momentum Selection
•Negative Axial Gradient in S.S. to suppress trapped particles ~0.2 T/m
•Detector Solenoid
January 25, 2010All Experimentors Meeting 4
Magnet Procurement Strategy
Fermilab will act as a “General Contractor”:
• PS and DS will likely be built in industry– Need to develop a strong conceptual design and technical specifications
for vendors
– Final engineering design done by industry
– Similar strategy for most detector solenoids
• TS will likely be designed/built “in house”– Cryostat, mechanical supports built by outside vendors
– Coils wound in-house or industry depending on technology choice
– Final assemble and test at Fermilab
• Fermilab responsible for all interfaces and infrastructure– Significant magnet coupling between PS-TS and TS-DS
– Tight mechanical interfaces
– Cryoplant, power supplies, instrumentation…
January 25, 2010All Experimentors Meeting 5
MECO vs. Mu2e Magnet Concept
Copper Bar
SSC cable
MECO Mu2e switches to… why?
Coils 96 Solenoid Rings Continuous MandelLess Joints, Less Field Ripple,
smaller conductor volume
SC Conductor SSC Excess Cable* New High Current CableLess layers, smaller inductance:
benefits cooling and quench protection
Quench Stabilizer Copper Extruded Aluminum (PS/DS)Less nuclear heating, vendor
experience with modern detector solenoids
Cooling Scheme Bath Cooled (PS) and Conduction (TS/DS)
Conduction onlySimplify cryostat design.
Possible in PS with Al stab. and new cable
*100 km of cable lost between 2005-2008
January 25, 2010All Experimentors Meeting 6
PS DesignVadim Kashikhin
•Long continuous inner coils with several short graded outer “tunable” coils for gradient field and to “match into” transport•Benefits relative to Meco
•Reduce coil volume by 50% (Conductor Grading)
•Reduce inductance by x5 (Increased operating current)
•Reduce nuclear heating >x2 (Aluminum Stabilizer)
“Graded Conductor”
January 25, 2010All Experimentors Meeting 7
PS Magnetic DesignMeco Two layer Continuous Wind Shorter Version
Vadim Kashikhin
January 25, 2010All Experimentors Meeting 8
Temperature and Current Margins are Acceptable
0 1 2 3 4 5 6 7 8 9 10 110
250
500
750
1 103
1.25 103
1.5 103
1.75 103
2 103
2.25 103
2.5 103
2.75 103
SSL @4.50KSSL @6.17KIL load lineOL load lineIL operating pointOL operating point
Peak field (T)
Cri
tica
l cu
rren
t de
nsit
y in
SC
(A
/mm
^2)
0 1 2 3 4 5 6 7 8 9 10 110
2
4
6
8
10
12
14
16
18
20IL SSL @4.50KOL SSL @4.50KIL load lineOL load lineIL operating pointOL operating point
Peak field (T)
Cri
tical
cur
rent
(kA
)
Temperature margin > 1.5 K
6.17 K SSL
4.5 K SSL
Current Margin I/Ic = 65 percent
Current M
argin
Current M
argin
January 25, 2010All Experimentors Meeting 9
2 Coil PS - Al cable (RRR 1100 - 600) - 5Tmax - 1kV
0
2000
4000
6000
8000
10000
12000
0 20 40 60 80 100 120
Time (s)
Cu
rren
t (A
)
0
10
20
30
40
50
60
70
RRR1100 - Current
RRR600 - Current
RRR1100 - Temp
RRR600 - Temp
RRR = 600
RRR = 1100
Compare to copper stabilizer: peak temperature ~85Kelvin
Quench Protection: Aluminum Stabilized + High Current Mu2e PSC
oil Peak T
emp
(Kelvin)
Exc
itat
ion
Cur
rent
(A
)
Aluminum is an effective stabilizer
G. Ambrosio
January 25, 2010All Experimentors Meeting 10
DS Design (model after Atlas)
2 T 1 T gap 1T 1 T
0m 0.93m 2.4m 4.17m 10.9m 11.9m
240 162 117 90 turn/m at 9 kA 127
2 Tesla2.5 m Aperture5 meters long
1 Tesla1.8 m Aperture7 meters long
Atlas Solenoid
R. Yamada
2 1 Tesla1.8 m Aperture2.5 meters long
January 25, 2010All Experimentors Meeting 11
TS Design
• We are interested in building simplest, cost effective, most reliable TS Systems
• Questions• Confirm that coils met MECO spec (done)• Confirm that muon transmission is insensitive to
coil alignment (done)• How sensitive is spec to coil placement? (done)• Coil options. Building SS and/or Toroid coils as a
single graded solenoid (ongoing)• Do we need corrector coils (ongoing)
R. Coleman / M. Lopes
January 25, 2010All Experimentors Meeting 12
Collaboration with Japan
Vl. KashikhinN. AndreevA. Makarov
Technology Magnet to Study Aluminum Stabilized conductor
Aluminum Stabilized Conductor
Hitachi
Magnet Construction ongoing: Test in spring 2010
Conceptual Design
January 25, 2010All Experimentors Meeting 13
Conclusion
• Significant amount of work done prior to CD0– Design of PS and a bit on DS
– Technology development with Japan
• CD0 CD1– Complete the conceptual design + cost and schedule est….
• PS mechanical supports for coils; thermal model for conduction cooling with expected beam induced heat loads; long vs. short length tradeoff
• TS work with experiment to define collimator interfaces, coil technology choice
• DS mechanical supports for coils especially end forces