WBS 4 Solenoid Magnets Update

1. WBS 4Solenoid Magnets Update Mu2e Working Group Meeting 27-Jul-2011 Thomas Page Solenoid Project Engineer

2. Outline • Internal Design Review in May, 2011 • Design status • RLS status • CDR status Mu2e WG Meeting

3. Internal Design Review • Internal Design Review held May 3-5, 2011 • Organized by Fermilab Directorate • Review Committee: • Pasquale Fabricatore (INFN Genova) • Joel Fuerst (ANL) • Alain Herve (UWisc) • Jim Kerby (Fermilab) chair • Herman ten Kate (CERN) • Akira Yamamoto (KEK) • 5 Recommendations and several findings Mu2e WG Meeting

4. Recommendations • Finalization of the conductor design, qualification tests, and subsequent procurement should be the highest priority of the solenoid effort. • Response: Collaboration with KEK, CERN (European); RFI for conductor. • The physics simulation effort studying operation off the design point must continue at a high priority. Results of these simulations will provide important input to the magnet design margin, the system design to include features to run off the design point, and acceptance test planning. • Response: Continued studies in progress. • Redesign the magnet systems using a lower and more typical value for the peak voltage of 600V. • Response: Peak voltages will be reduced. • The 1.5K temperature margin for the solenoids should be documented and closely guarded at this phase of the project. The margin on the production solenoid should be increased. • Response: Design iteration with improved margin in progress. • A complete R&D plan needs to be developed to answer open questions in a timely manner. Coordination with CERN and KEK efforts may help accelerate the program. • Response: In progress. Mu2e WG Meeting

5. Conductor Development • Conductor development is high priority, esp. for PS (Recommendation 1). • Short term plans: • RFI to industry to get vendor interest and feedback on conductor. • Place an order for a short length (~200-400 m) of each type of conductor (PS & DS). • Collaboration with KEK, European collaboration (Recommendation 5) • KEK has recently purchased similar cable so we are using this experience as a guide. Cost and lead time will be similar. • There is a European collaboration with industry to build new ATLAS cable. We will follow this collaboration and see how Mu2e can fit into this collaboration. Mu2e WG Meeting

6. US Japan Agreement • Development with Japanese industry of prototype aluminum stabilized NbTi cable suitable for Comet or Mu2e • Two cables: 5 kA cable and 10 kA cable (~200 m each) • 10 kA cable will be made into a small COMET/Mu2e prototype coil by Japanese industry • Fermilab is upgrading its test capabilities to test large aperture, conductively cooled solenoids • Facility would be used to test TS modules. Mu2e WG Meeting

7. US Japan Agreement • Schematic of the prototype coil which will be made in Japanese industry. Mu2e WG Meeting

8. US Japan Agreement • Studies of resistivity degradation as a function of radiation dose. • Results of radiation studies at Japanese reactor show • Damage to stabilizer is real effect • Room temperature anneal is effective in restoring RRR • VitalyPronskikh analysis supports the idea that we can run for ~1 year before having an anneal • Based on our requirement of RRR degradation <5 • i.e. consistent with anticipated cryoplant maintenance Mu2e WG Meeting

9. PS Design Status Aluminum sheets for thermal propagation Mu2e WG Meeting

10. PS Design Status • Temperature margin was small, working to increase the margin in the PS superconductor (Recommendation 4). • Thinner cable (6.6mm6.0 mm) • Thinner insulation (adapt ATLAS scheme) • Lower current density  more thermal margin • Slight increase in peak temperature from quench • Coils • Length of 3 coils are now the same • Improved aluminum sheets to remove dynamic heat, spread quench energy. • Lowered maximum field slightly (still within spec, see next slide) Mu2e WG Meeting

11. Magnetic model Mu2e WG Meeting

12. Updated parameters Previously: Current sharing temperature (at I op) =6.24K Mu2e WG Meeting

13. T0=4.6 K, static+dynamicheat load • Peak coil temperature increment is 281 mK; • ~30 mK higher than in the previous design. • Peak coil temperature is below the maximum allowable temperature of 5.00 K. Mu2e WG Meeting

14. Parameter space • Temperature margin at T0=4.6K: • 1.62 K at the nominal heat depositions; • 1.55 K at 25% higher heat depositions; • 1.49 K at 50 % higher heat depositions. • T0 temperature to achieve 1.5 K margin: • 4.72 K at the nominal heat depositions; • 4.66 K at 25% higher heat depositions; • 4.59 K at 50 % higher heat depositions. Mu2e WG Meeting

15. PS Iron Yoke • The iron yoke walls moved towards the coil by 50 mm each to make the same square opening as in DS magnet. • The yoke thickness was reduced to what is necessary to shield the fringe field. Mu2e WG Meeting

16. TS Design Status • We are considering powering TS3 in series with TS4/5; i.e. remove one power converter. • Conductor issue with commercial “wire in channel” • Large filament diameter can make conductor unstable at low field • Primary US vendors seems unwilling to alter formula for us • Plans: • Widen search to all global conductor vendors • Consider aluminum stabilized conductor • RFI for TS conductor in the pipeline Mu2e WG Meeting

17. TS Design Status • Difficulty in applying Axial Preload on individual rings • Copper shrinks away from Stainless steel mandrel end flanges • Complicated by non-linear forces during normal operation • Possibility of powering down adjacent solenoid segments during commissioning and quench scenarios • Solutions • Consider Aluminum Mandrels • Limit running scenarios to reduce force excursions • For e.g Never power TS12 with PS on and TS3 off • Possibly go to a aluminum stabilized conductor Mu2e WG Meeting

18. Studying Displacements • Studies are ongoing to understand the effect of conductor placement errors (random and systematic) on muon transmission and backgrounds (Recommendation 2). • Work being done by Mau Lopes. • Need to determine warm coil position to account for cool down and excitation in cold position. • Need to have the ability to adjust coil position once cryostat is assembled. • Further studies needed to understand reproducibility of coil movement from cool down and excitation • Instrumentation to measure coil position during operation? Mu2e WG Meeting

19. X X Z Z Studying Displacements 28.0 21.7 35.3 27.4 10.4 6.7 1.2 2.5 2.1 5.7 7.1 0.8 6.0 6.8 31.8 23.9 0.6 2.6 2.6 8.7 8.7 2.5 0.3 3.5 3.6 0.6 1.8 1.0 0.4 1.8 14.0 7.8 0.2 1.2 ALL ON PS OFF Mu2e WG Meeting

20. DS Baseline Design • Several coil and conductor configurations were considered • Base line for CD1 is : • Two axial coils. Each: 2 layers • Two conductors • Axial spacers to achieve field gradient Mu2e WG Meeting

21. DS Design Status • Comments from May 2011 • Conceptual design was workable • E/M ratio is very low • i.e. Over designed from a quench protection stand point • We are studying ways to simplify design/reduce mass • Consider a single layer coil in spectrometer section. • Need to study “return bus” affect on field uniformity • Consider using PS conductor in gradient region. Mu2e WG Meeting

22. Ongoing Tolerance Studies • Design changes considered (Recommendation 2). • Varying number of coil blocks • Allow for inner/outer spacers to have different dims. • Spectrometer section, single layer. • Possibility to change improve DS design • Studies have been performed to understand the impact of construction errors on field quality. • Parameters: • +/- Turns • Coil block length, coil longitudinal position • Coil radius, coil ovality Mu2e WG Meeting

23. DS Sensitivity Study Mu2e WG Meeting

24. Gradient in Spectrometer Region? • Present DS spec is dB/B +/- 1 percent, in tracker/calorimeter region. • There is evidence that a systematic positive gradient would be a problem. • Positive gradient could occur as a result of a improperly controlled winding tensioning, or systematic error in conductor or insulation thickness. • A built-in negative gradient would assure that this would not occur. • Simplest way to do this would be to reduce the amp turns in coil 10 or shorten coil 9. • This issue is still under discussion. Mu2e WG Meeting

25. RLS Status • Schedule has been developed, needs to be fine tuned to reduce overall duration where possible. • Cost and labor estimates for CD-1 have been complete. • Labor estimates given to D. Leeb for input into P6, ~ 60% complete. • M&S is being input into P6 by T. Page, ~ 50% complete. • First version of BOEs and supporting documents uploaded to DocDB. These will have to be revised after total labor hours are complete in P6. • Estimates done in man-months and when entered into P6 as hours there are small discrepancies / round off errors that need to be corrected. • Links have been added to WBS 4.3 (Conventional Construction) but I have not seen links to other L2s. • Most likely won’t drive solenoid schedule but the solenoid schedule may drive other L2s. Mu2e WG Meeting

26. CDR Status • The CDR is being revised by M. Lamm. • Revised chapter ready by 29-Jul-2011. • Incorporates latest updates to PS and TS. Mu2e WG Meeting

27. Summary • Recommendations and comments from review were very useful and are being implemented into the solenoid designs. • Looking at ways to simplify designs to reduce complexity and cost. • Solenoid portion of the RLS is in good shape. • Needs to linked with other L2’s for completeness. • Needs to be studied to find ways to reduce overall duration if possible. • CDR is in good shape for upcoming reviews. Mu2e WG Meeting

28. End Mu2e WG Meeting