Michelle Espy email: [email protected] SQUID NMR Signal Outline Overview of SQUIDs in EDM: present...
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Transcript of Michelle Espy email: [email protected] SQUID NMR Signal Outline Overview of SQUIDs in EDM: present...
Michelle Espy email: [email protected]
SQUID NMR Signal
Outline• Overview of SQUIDs in EDM: present thinking
- experimental design ideas- expected signal, SQUIDs
• Update on SQUID NMR/MRI progress • Obstacles and Issues• 15 month plan
- Final Design- Noise tests- NMR tests on polarized 3He- High voltage tests
Michelle Espy email: [email protected]
Overview of SQUIDs in EDM: present thinking
Experimental Design Ideas (big coils vs. gradiometers)
Expected signal in 40x4 cm2 coil 13.5 m0 – coupling to
SQUID ~1% for ~ 10-4 0. SNR ~10
Expected signal in one gradiometer 10-19 Wb, limit 2x10-19 Wb SNR ~ 1/3 : Definitely Need Array
Michelle Espy email: [email protected]
Overview of SQUIDs in EDM: present thinking
Expected Signal, SQUIDs
- Clearly signal larger for big coil
-Vibration
-Gradiometer advantages
- Array of gradiometers
- (12x12 with 36mm baseline)
- Gradiometers AND big coils, “big” gradiometer?
- Modeling Requirements (Chen-Yu)
-Multiple SQUIDs? Coil position? Other designs, 48x48 – make grads wider?
Michelle Espy email: [email protected]
- Measurements through/in presence of metal- Electronics for helping SQUIDs survive pulse, pulse sequences, cryoswitch already exists- Systems/hardware in place for tests- Understanding of NMR issues (transients, eddy currents etc.)
Update on SQUID NMR/MRI progress
Simultaneous measurements of biomagnetic signals and anatomy
B0 = 60 G, Bm = 5.5μT
Volegov, et al., Mag. Resn. Med., 52, 467 (2004)
Michelle Espy email: [email protected]
7-channel ULF-MRI reconstructed using SENSE (sensitivity encoding) approach
Distortions due primarily to Bp inhomogeneities
T2* Contrast Image at 12T(First ever T2* contrast image at T fields)
Kraus, et al.,
Human Brain Mapping (2005)
Density Contrast image of Human Hand
Zotev, et al.,
4EG08
ASC (2006)
Update on SQUID NMR/MRI progress
Michelle Espy email: [email protected]
Remaining Obstacles and Issues
- Vibration noise
- Leakage current from HV electrodes
- Johnson noise – mu metal inside superconducting shield, electrode material, sc shield material
- Eddy currents
- Other noise sources
- Feed-throughs
- Andrei/Steve discussion about RF shielding
Michelle Espy email: [email protected]
15 month plan
What needs to be done/ what we can offer:
Modeling, final design of SQUIDs
SQUID/pick-up testing
Noise testing (Johnson noise of materials - easy at 4K, can be moved into dilution refrigerator)
NMR tests on 3He with SQUIDs
HV Test with SQUIDs
NMR signal extraction (experience with ULF-NMR, multiple component analysis, NIH grant)
Michelle Espy email: [email protected]
15 month plan
Task: Cost:Modeling final SQUID designPetr/Andrei/Michelle (2wks) 17.5
Designing final SQUID/coilsAndrei(1wk) Tech(1wk) 15
Assembling SQUID/coilsAndrei(1wk) Tech(1wk) M&S 5k 20
SQUID/pick-up testing and Noise Testing platformDewar/Shielded room already in placeInsert - Andrei(2 wks) Tech(4 wks) M&S 15K 57.5
Noise testing at 4KAndrei/Michelle (4 wks) 35J ohnson noise of materials - easy at 4K, can be moved into dilution refrigerator
NMR tests on 3He with SQUIDsAndrei/Michelle(4 wks) 35At LANL or another location? Assume we have the SQUIDs to use
HV Test with SQUIDsAndrei/Michelle(2 wks) 17 Assume we have the SQUIDs to use
NMR signal extraction - modeling and results of 3He testsPetr/Michelle/John (4 wks) 35(experience with ULF-NMR, multiple component analysis, NIH grant)
Designing Feed-throughs/RF ShieldingAndrei(2wk) 17.5(This depends largely on other estimates of noise- does not include fabrication)
249.5