1. 1 Update of the injection test 06/2007 nEDM H. Gao, M. Busch, Q.Ye, T. Mestler, X. Qian, W. Zheng, X. Zhu Duke University And others in nEDM collaboration

2. 2 Outline Magnets system collection reservoir – Pyrex Cell design – Cs coating – monitoring 3 He- 4 He mixture Design of Pulsed NMR system

3. 3 Superconducting Magnets Tri-coils and solenoid coils – 20G,spin rotation of 45 deg. – 1.2KG, holding field for NMR Tri-coil – A bath of liquid He Cooling can built by MIT – June, by Cryomagnetics Solenoid coil (Cu:NbTi) – Conductive cooled by Al6061 mandrel – June, by AMI Tri-coil --Caltech Solenoid coil

4. 4 Power supply for superconducting solenoid A Kepco Power supply with quench protection – Cost reduced by a factor of 10 – Power supply from Superconducting magnet company is an overkill, too expensive – Pure inductive load, ~1400V spike voltage at quenching

5. 5 New design of collection reservoir Glass to metal adaptor Glass joint with kapton O- ring is hard to seal A separated bottom cell – Closer to final test. – Solenoid coil for pNMR is applicable Instead of side coil – Smaller sample size Longer T2: ~5.5ms pre-filled 4 He Bottem cell for pNMR NMR solenoid Probe coil

6. 6 Cell inner Surface treatment at room temperature Cs coating reduces wall depolarization effect – Cs Azide Rod moves down into top/bottom cell – heating Cs Azide (CsN3) rod Cs moves straightly in vacuum No shadow area Cs Azide rod

7. 7 3 He- 4 He mixture temperature and pressure measurements provide valuable information – 3 He vapor concentration X : – 3 He liquid concentration X liq, W/k=1.54 Kelvin – Applicable at equilibrium state P.J. Nacher, J low Temp. Phys V97, p417,1994 ~10 temperature sensors will be installed Ruthenium Oxide RTDs from Lakeshore

8. 8 Polarization measurmnet Plused NMR – Resonance frequency at 3.89MHz – Very low density of 3 He: 10 14 atoms/cc Very good signal to noise ratio – Must Push what is possible for pNMR – Most helpful to have squids detector Will squids work without magnetic shielding?

9. 9 Schematic of pNMR probe Signal in the probe coil – >160V during RF transmitter – ~1uV NMR signal of FID Inside dewar RF amp Apollo console from NCSU

10. 10 pNMR : tank circuit Tank circuit: – Probe Coil at resonance Inductance: 32uH with 40 turns – Tunable capacitor non magnetic low temperature High voltage – piston trimmer

11. 11 Resonance tuning inside dewar Piston trimmer close to probe coil Very small signal: 1nV/loop the circulating current does not need to go through the coax Piston trimmer capacitor ordered – 5~120pF Number of turns C (pF)

12. 12 Probe of pNMR close to our design Rev. of Sci. Instr. 68, 2132 (1997).

13. 13 COAX connects the tank circuit High-Q Coax cable: – inner: Ag plated BeCu – outer: CuNi – insulated with Teflon good electric conductivity Poor thermal conductivity Courtesy by Dr. William Halperin, NWU

14. 14 Inhomogeneous B1 field for single solenoid probe coil A separate Helmholtz coil for RF power transmitting is under design Spins rotate by 90 deg. RF pulse duration time: ~100uS B1 field: 7.6G 2cm

15. 15 pNMR: RF amplifier From Tomco – Linear amplifier type: AB – Blanking time ~1us 1dBm=0.22V – RF noise:~ 0.2uV

16. 16 pNMR: lumped circuit and RF Amplifier lumped circuit Works as a duplexer – Block pre-amp during RF transmitting – Conducting for FID RF Amplifier From Tomco – Blanking time ~1us 1dBm=0.22V – RF noise:~ 0.2uV Zi Zo = Z 2 = 1/ω 2 c 2

17. 17 Other studies on cryogenic pNMR Low noise high impedance Pre-amp Q-spoils circuit to shorten the recovery time Ground loop Ultrasonic noise

18. 18 Schedule Test and install the magnet system in June, July and August Start pyrex cell fabrication June and July Optimize pNMR system – To see glycerol signal with Apollo console at low field – Improve the signal/noise ratio at room temperature – Cool the sample and tank circuit – improve signal at low temperature June, July and August

19. 19 Thanks!

20. 20 Design of Feed through and trimmer handle BNC-SMA Hermetically sealed SMA bulkhead SMA-coax adaptor Courtesy by Dr. William Halperin, NWU