1. TD Designs for mu2e Solenoid Magnets Michael Lamm for the Mu2e Collaboration and TD/Magnet Systems Dept. All Experimenters’ Meeting January 25, 2010

2. All 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

3. January 25, 2010 All Experimentors Meeting 3 Magnet System by Function Production Solenoid 8 GeV P Transport Solenoid Graded field to collect conv. e - (2T  1T) 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 5T  2.5T Sign/momentum Selection Negative Axial Gradient in S.S. to suppress trapped particles ~0.2 T/m Detector Solenoid

4. January 25, 2010 All 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…

5. January 25, 2010 All Experimentors Meeting 5 MECO vs. Mu2e Magnet Concept Copper Bar SSC cable

6. January 25, 2010 All Experimentors Meeting 6 PS Design Vadim 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”

7. January 25, 2010 All Experimentors Meeting 7 PS Magnetic Design MecoTwo layer Continuous WindShorter Version Vadim Kashikhin

8. January 25, 2010 All Experimentors Meeting 8 Temperature and Current Margins are Acceptable Temperature margin > 1.5 K 6.17 K SSL 4.5 K SSL Current Margin I/Ic = 65 percent Current Margin

9. January 25, 2010 All Experimentors Meeting 9 RRR = 600 RRR = 1100 Compare to copper stabilizer: peak temperature ~85Kelvin Quench Protection: Aluminum Stabilized + High Current Mu2e PS Coil Peak Temp (Kelvin) Excitation Current (A) Aluminum is an effective stabilizer G. Ambrosio

10. January 25, 2010 All Experimentors Meeting 10 DS Design (model after Atlas) 2 T 1 T gap 1T 1 T 0m0.93m2.4m4.17m 10.9m 11.9m 24016211790 turn/m at 9 kA127 2 Tesla 2.5 m Aperture 5 meters long 1 Tesla 1.8 m Aperture 7 meters long Atlas Solenoid R. Yamada 2  1 Tesla 1.8 m Aperture 2.5 meters long

11. January 25, 2010 All 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

12. January 25, 2010 All Experimentors Meeting 12 Collaboration with Japan Vl. Kashikhin N. Andreev A. Makarov Technology Magnet to Study Aluminum Stabilized conductor Aluminum Stabilized Conductor Hitachi Magnet Construction ongoing: Test in spring 2010 Conceptual Design

13. January 25, 2010 All 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