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Steve Williamson UIUC

3He Relaxation. Steve Williamson UIUC. 6.2 ABS Interface. 6.5 Purifier. 6.1 3He Atomic Beam Source (ABS). 6.3 Polarized 3He Collection System. 6.10.1 Cell Isolation (V1) Valve Actuators and Interfaces. 6.11.3 Pressurizer/Cell Interconnect Plumbing. 6.10.6 Purifier isolation (V6) Valves.

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Steve Williamson UIUC

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  1. 3He Relaxation Steve Williamson UIUC nEDM Collaboration Meeting, May 25-26, 2006

  2. 6.2 ABS Interface 6.5 Purifier 6.1 3He Atomic Beam Source (ABS) 6.3 Polarized 3He Collection System 6.10.1 Cell Isolation (V1) Valve Actuators and Interfaces 6.11.3 Pressurizer/Cell Interconnect Plumbing 6.10.6 Purifier isolation (V6) Valves 6.10.4 Collection Isolation (V4) Valve 6.10.3 Pressurizer Standoff (V3) Valve 6.10.2 Pressurizer Isolation (V2) Valve 6.10.5 Purifier Control (V5) Valve 6.11.2 Collection/ Purifier Interconnect Plumbing 6.8 Pressurizer The 3He Services (He3S) Subsystem 6.11.1 Volume Displacement Interconnect Plumbing 6.6 Volume Displacement nEDM Collaboration Meeting, May 25-26, 2006

  3. The 3He Services (He3S) Subsystem 6.2 ABS Interface 3He Friendly Materials 6.5 Purifier 6.1 3He Atomic Beam Source (ABS) 6.3 Polarized 3He Collection System 6.10.1 Cell Isolation (V1) Valve Actuators and Interfaces 6.11.3 Pressurizer/Cell Interconnect Plumbing 6.10.6 Purifier isolation (V6) Valves 6.10.4 Collection Isolation (V4) Valve 6.10.3 Pressurizer Standoff (V3) Valve 6.10.2 Pressurizer Isolation (V2) Valve 6.11.1 Volume Displacement Interconnect Plumbing 6.10.5 Purifier Control (V5) Valve 6.11.2 Collection/ Purifier Interconnect Plumbing 6.8 Pressurizer 6.6 Volume Displacement nEDM Collaboration Meeting, May 25-26, 2006

  4. What Materials are 3He Friendly? • We have focused on dTPB in the cell • But for seals, interconnections, and valves, we also need to characterize other materials. • Nylon – Big CTE, good for seals • Teflon – Remains ductile at low temperature, good for valve bellows • Kapton – proposed for seals • dStyrene – cheaper than dTPB coating, for pipes? • DryFilm – Could be used to coat unfriendly materials • Composite Carbon or G10 – 1200 l volume end-caps • etc. etc. … nEDM Collaboration Meeting, May 25-26, 2006

  5. An Example H-gasket Seals on inside on warm-up Nylon (LARGE CTE) Copper Acrylic H-gasket Seals on outside on cool-down But is Nylon 3He Friendly? nEDM Collaboration Meeting, May 25-26, 2006

  6. Bad Good Glass Valve • Single cell with valve like that used in Duke experiments. • Good signal, reasonable T1, T2 • But signal decline and eventual loss after about 10 days. • Leak? Outgassing? nEDM Collaboration Meeting, May 25-26, 2006

  7. Double Cell: Install in Cryostat • 2.8 m double cell • Glass thermal links: • Few hundred strands of ~ 32 gauge Cu wire twisted under tension around glass. • Links at 4, 1.2, 0.4 K • Thermal contact improved with Apiezon N vacuum grease. • Just vacuum, (no 3He). nEDM Collaboration Meeting, May 25-26, 2006

  8. Cooldown • Cell cooled – early May • New record low for 3He pot temperature 1.2K anchor A:1.36K E:0.33K F:0.31K B:0.55K Turbo Off 3He evaporated C:0.82K 0.4K anchor D:1.64K nEDM Collaboration Meeting, May 25-26, 2006

  9. Cooldown • Glass temperature distribution seems odd. • Poor thermal contact of lowest sensor? • More effective radiation heating of bottom from IVV? • “Baked Potato” effect? • Improve thermal connection to glass using Cu foil, GE varnish • smoothly, despite departure of refrigerator designer/operator for greener pastures. nEDM Collaboration Meeting, May 25-26, 2006

  10. Pump Cell Fill Release Vacuum Measure. Cell Next Steps • Solve valve contamination problem • Build new 3 m double cell with valves • Valve for pumping • Valve for filling • In-line valve to release Polarized 3He into measurement cell • Measure NMR at 300 K with “standard” coils • Build new flip and pickup coils for cryostat • Cooldown and measure NMR at 0.3K • Cold test with 3 m double cell (glass) • Cold test with 3 m double cell (acrylic cold cell) • Room temperature testing (relaxation) of key materials • acrylic • Cu-Ni? • Si-Bronze? • Cold testing of materials nEDM Collaboration Meeting, May 25-26, 2006

  11. 3He Dressed Spin Studies • 3He dressed-spin effect observed at LANL with ABS beam. Now try in a cell. • Normal “optical NMR”: • Once the cell is polarized, Bx is applied at the Larmor frequency to rotate the ensemble polarization • Flourescence optical signal intensity varies with z-component of the polarization. • Modulation reveals the spin precession about Bx nEDM Collaboration Meeting, May 25-26, 2006

  12. Results • Polarization rotation frequency  = 3HeBx • An additional high-frequency field (dressing field) can modify the effective moment. 30% Change in effective magnetic moment nEDM Collaboration Meeting, May 25-26, 2006

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