1. nEDM Preliminary Engineering Review Magnets & Magnetic Shielding
Subsystem overview
Subsystem Specification & Components
Subsystem Costs + Schedule
Magnets & Cryogenic Shields (BF)
R&D, Prototyping, Performance
Room Temperature m-metal Shields (BP)
Performance, Cost, Re-scoping
Engineering Issues (JB)
Mechanical, Cryogenic, Assembly
Magnet/Cryoshield R&D, Design, Strategy
Summary & Open Issues...
ORNL 12/15/08

2. Design Document Draft (posted on web)

3. Principle Design Specifications
Note: B0 uniformity of 5x10-4 gives T2 ~ 3000s at 0.4K in 40cm cell
= 15% loss of polarization over meas. cycle
gives T2 ~ 1000s at 0.45K
= 40% loss of polarization over meas. cycle
Optimum T2 spec. = 30,000s
But...
<P> = 3000s
<P> = 1000s

4. Subsystem Elements and People
WBS Number
Work Package
Work Package Leader
1.5.1
Four-Layer Conventional Shield
Brad Plaster
1.5.2
Superconducting Shield
Bob Carr
1.5.3
Constant Field Coil Ferromagnetic Shield
1.5.4
B0 Field Coil and Gradient Field Coils
BF & BP
1.5.5
Dressed Spin Coils
Riccardo Schmid
1.5.6
Field Monitors
BP & BF
1.5.7
Test Cryostat
1.5.8
3He Spin-Holding Coil
Ricardo Alarcon
1.5.9
3He Spin-Holding Coil Ferromagnetic Shield
1.5.10
Full System Tests of Magnet Package
Brad Filippone

5. Project Costs NSF Total CD2 CostnCon
1.5 Magnets & Magnetic Shielding $2,429,619
1.5.1 Four-Layer Conventional Shield $1,459,173
1.5.2 Superconducting Shield $63,165
1.5.3 Constant Field Coil Ferromag. Shield $125,570
1.5.4 B0 Field Coil and Gradient Field Coils $215,108
1.5.5 Dressed Spin Coils $219,430
1.5.6 Field Monitors $116,201
1.5.7 Test Cryostat $0
He Spin-Holding Coil $92,681
He Spin-Holding Coil Ferromag. Shield $64,534
Full System Tests of Magnet Package $73,756
$2,842,470
$1,465,722
$100,277
$138,638
$284,275
$271,077
$116,201
$140,727
$141,630
$71,068
$112,856
Cost Basis is in Cost Sheets for Work Packages
(to be reworked later this week!)
Shield (see BradP), others based on prototype costs + vendor quotes

6. Project Schedule “Highlights”
Start Finish Work WP dur Dur+Sch Duration
1.5 Magnets & Magnetic Shielding Wed 2/14/07 Thu 5/30/13 19,844h 8359d 442.8d 2298d
1.5.1 Four-Layer Conventional Shield Wed 3/5/08 Mon 7/18/11 2,403h 1713d 313.2d 1231d
1.5.2 Superconducting Shield Wed 2/14/07 Sun 11/21/10 540h 720d 432d 1377d
1.5.3 Constant Field Coil Ferro Shield Wed 2/14/07 Mon 1/18/10 360h 480d 216d 1070d
1.5.4 B0 Field Coil and Grad Coils Wed 2/14/07 Mon 6/13/11 4,640h 903d 367.2d 1581d
1.5.5 Dressed Spin Coils Wed 2/14/07 Mon 8/8/11 3,216h 940d 442.8d 1637d
1.5.6 Field Monitors Wed 2/14/07 Tue 5/3/11 1,192h 750d 324d 1540d
1.5.7 Test Cryostat Wed 2/14/07 Wed 6/16/10 1,225h 514d 208.8d 1219d
He Spin-Holding Coil Wed 2/14/07 Tue 1/31/12 2,983.98h 1265d 403.2d 1813d
He Spin-Holding Coil Ferr Shield Wed 2/14/07 Fri 5/14/10 768h 480d 216d 1186d
1.5.10Full Sys Tests of Mag Package Tue 7/19/11 Thu 5/30/13 2,516h 594d 259d 682d
Needs Work!!

7. Design Items to be Covered
Lower cryostat Magnet Package
Upper Cryostat 3He Magnet & Ferromag. shield
m-metal external Magnetic Shield
Engineering the Subsystem

8. Magnets and Cryogenic Shields
System Component
Radius [m]
Length [m]
Inner Dressed Spin cos θ Coil
0.50
4.16
Outer Dressed Spin cos θ Coil
0.59
B0 cos θ Coil +Gradient Coils
0.65
B0 Ferromagnetic Shield
0.67
Pb Superconducting Shield
0.69
3He cos q Coil
0.20
1.25
3He Ferromagnetic Shield
0.21
1.35

9. 3He Holding Coil (upper cryostat)
Cosq magnet with ferromagnetic (Metglas) shield
Design is similar to B0 magnet, but...
Large penetration through side is needed for 3He injection
Penetration has been modeled in TOSCA

10. TOSCA FEA simulations Cosq coil with hole for 3He injection Cosq coil
with symmetric gaps in shield and modified coil windings

11. Magnet Package (lower cryostat)

12. nEDM Magnet Package

13. Dressed Spin Coil Design
AC B-field of dressing coil produces eddy-currents in ferromagnetic shield
Cosq coil with B1=1G, n = 2kHz  Power ~ 60 Watts
Additional coil that mimics induced currents on superconducting cylinder reduces AC B-fields

14. Dressed Spin Simulation & Prototype
<|Bx|> (Gauss)
I2/I1

15. p/2 Spin Rotation Coil Use inner dressing coil as p/2 coil...
Works well, thus remove separate coil
Spin
simulation

16. B0 R&D Progess
Cryogenics tests (at 4K) completed on 1/7 scale coil with ferromagnetic (Metglas) shield and Pb SC shield
SC shield very effective at limiting magnetic noise, but boundary conditions worsen uniformity – improved by Metglas
1/2 scale coil & ferromagnetic shield constructed
Promising results suggest “... the resulting gradient will satisfy the CD-4 requirement”

17. 1/7 Scale Coil 1/7 scale coil built with Al form and Al wire
Tested with Ferromag. & SC Pb shields
Thanks to S. Balascuta (ASU) for TOSCA calculations
nEDM November 2007 Collaboration Meeting
B. Plaster

18. 1/7 Scale Coil
Map of Bx(z) for N=40 cos θ coil + Metglas + Pb at 4 K

19. ½ Scale Coil Design nylon/G10 spacers
match thermal contraction of Nb/Ti-Cu wire
Rings slide in slots on acrylic tube
acrylic tube
24” O.D.
7.5’ length
7  3-ring-sets of wire locators
defines wire radius
B. Plaster

20. As-built coil 3-ring set Nylon/G10 spacer stand-off rods
spring-loaded wire tensioners
nEDM May 2008 Collaboration Meeting
B. Plaster

21. ½ Scale Coil Completed Coil mounted in magnetic mapping device
Large dewar for 4K tests of ½ scale coil will arrive in Jan. 08

22. Ferromagnetic Shields for ½ scale Coil
Using 0.001” x 2” strips of Metglass 2705M
Inner shield (3 layers on “sewar pipe”) provides more uniform field for B0
Outer Shield (4 layers on Sonotube
shields room background)

23. ½ Scale Coil, no Metglas Shield

24. ½ scale prototype performance with two Metglas shields Recent coarse volume scan:

25. Gradient Coils x z z

26. Acceptance Testing Plan
m-metal shield
vendors – measure shielding
Assemble at Caltech – measure shielding
½ scale B0 package
Measure heat loads, cooling times, uniformity, magnetic noise with Ferro. Shield + Pb Shield
Test atomic magnetometers, SQUIDS(?), other
Dressing coil
Uniformity
Active shield performance
B0 testing
Warm high-field tests
Warm low-field testing in m-metal shield
77K horizontal high-field
Magnet package thermal load

27. Synchrotron Lab (Caltech)
EDM B-mapper

28. Synchrotron Lab (Caltech)

29. Possible B0 Test Cryostat

30. Safety Issues For Subsystem
Hazards and Hazard Mitigation
The principal hazards that have been identified for this subsystem are
Electrical safety associated with magnet power supplies and degaussing circuits
Alternating current: up to 20A at 3kHz for dressing coils
AC magnetic fields: up to 5 gauss at 3kHz
Hazardous materials: e.g. Pb, Metglas, G10
Craning of heavy loads
To mitigate these hazards:
Use UL approved power supplies wherever possible
If this is not possible we will ensure that the power supplies satisfy the
electrical safety requirements of ORNL.
The magnetic fields that we produce within our apparatus will be shielded to a level
comparable to ambient levels.
MSDS will be provided for identified hazardous materials and personnel will be
trained for use.

31. Additional Slides

32. Are the appropriate models/drawings provided for the sub-systems
Are the appropriate models/drawings provided for the sub-systems?  Are the drawing specifications appropriate?
Are the components compatible with each other and the neighboring sub-systems?
Have appropriate analyses and/or simulations been performed on the individual components?  These would include finite element, heat transfer, thermal contraction, etc.
Do the present design specifications meet the material requirements set forth by the other sub-systems such as neutron activation/absorption, depolarization, magnetism, electrical conductivity, etc.?
Are there any issues associated with assembly and/or service and repair?
Have the appropriate acceptance tests been identified?
Have the costs and delivery times been properly identified? 
What options should be explored for value engineering?

33. Johnson Noise Estimates

34. Control of Systematics
3He Co-magnetometer monitors B-field changes
“Dressed Spin” mode reduces sensitivity to external B-field variations
Geometric Phase effect (false EDM due to motional field ) can be controlled with uniform B-fields
(see next two talks...)

35. Temperature Profile

36. 4 K Heat Shield Body and Supports – Symmetric Model
Heat Shield Body Support Ring
Heat Shield/Magnet Package Locator
Heat Shield/Magnet Package Mount Support
Generic Magnet Package
Heat Shield Body

37. Component Weight and Boundary Conditions
4 K Heat Shield Body and Support Rings Assembly – 770 lbs
Calculated value using the density of Aluminum 1100-O
Generic Magnet Package – lbs
Calculated value using the density of G10
4 K Heat Shield/Magnet Package Locator Plate – 23 lbs
Heat Shield/Magnet Package Mount Support – 13 lbs
Analysis 1:
Fixed restraint is applied to:
heat shield body rear mount location
backside magnet package flange
Upstream mount adapter support
Standard Gravity Load.
Contact elements between dielectric roller and heat shield.
Assumes no sliding and separation between faces or edges is allowed.
Contact elements between heat shield body and support rings.
Contact elements between bushings and support posts.
Assumes no sliding and separation between faces or edges is allowed
Analysis presents itself as a symmetric problem.

38. FEA Deformation Results – Heat Shield

39. FEA Stress Results Body Support Rings Heat Shield Body
Hoop Stress: 147 psi (tension)
yield 5.00 ksi
Deformation: in (max)
Heat Shield Body
Hoop Stress: 560 psi (compression)
Deformation: in (max)
Dielectric roller
Contact Pressure: ~900 psi
Bushing/Pin
Contact Pressure: ~2027 psi

40. Summary First Order Analysis: Higher Order Analysis
Mesh quality – medium
Mesh Statistics
Nodes –
Elements – 54599
Bolted Joints were not considered.
Used bonded contact to reduce computational time.
Higher Order Analysis
Convergence/adaptive mesh
Include bolted joints and frictionless contact

41. An interesting systematic effect
Geometric Phase
Path-dependent phase
E.g. Parallel transport of vector on sphere
In Quantum Mechanics often called Berry’s phase

42. BE = E x v field Radial B-field due to gradient E x v field
changes sign with
neutron direction

43. False EDM from Geometric phase
Pendlebury et al PRA (04)
Lamoreaux and Golub nucl-ex/
Geometric phase gives false EDM that depend strongly on radial B fields perpendicular to B0
These result from dB0/dz