Design of a Hybrid 3 He Polarizer: Measurement Techniques and Construction. Karen Mooney University of Virginia March 25, PDF Free Download

Design of a Hybrid 3 He Polarizer: Measurement Techniques and Construction Karen University of Virginia March 25, 2008

Polarizer Basics

New Polarizer Advancements More Gas 3.0L/day Vs 1.0L/day Higher 60% Vs 40% Rb-K Hybrid Cell Narrowed Diode Lasers Enhanced Diagnostics AFP NMR w/ EPR calibration Vs Pulse NMR w/ Water calibration

Measuring Nuclear Magnetic Resonance (NMR) Polarized 3 He nuclei are aligned with an external magnetic field He Nuclear Spins are flipped by applying a transverse RF Faraday Induction signal detected in mutually perpendicular coils Signal detected is proportional to 3 He polarization Holding H Helium Spin

Measuring Adiabatic Fast Passage RF H 1 Holding H Helium Spin

Measuring AFP RF H 1 Holding H Helium Spin

Measuring AFP Helium Spin RF H 1 Holding H

Measuring AFP RF H 1 Holding H Helium Spin

Measuring AFP Adiabatic- is swept slowly so that the spin can follow it Fast- The is swept quickly enough so that the spins do not relax in the low field region. Holding H Helium Spin

Measuring AFP Schematic -Holding (H) -RF H 1 (ω) - - Pick Up Coils x z y -EPR Coil EPR Photo Diode

Measuring AFP Signal Lock-In Signal A Spin Up Fit Sample NMR Signal Sample Spin Up Taken 01/2008

Measuring Electron Paramagnetic Resonance

Measuring EPR- Measuring Frequency Shift

Measuring EPR- Monitoring Frequency

Measuring EPR- Reversing 3 He RF H 1 Holding H Helium Spin

Measuring EPR Schematic -Holding (H) -RF H 1 (ω) - - Pick Up Coils x z y -EPR Coil EPR Photo Diode

Measuring Main Optical Pumping Oven

Measuring Calculating Calibration Procedure Take NMR Do EPR Take NMR Calculate P He Average NMR Signals Get %/mv Calibration

Measuring Calibrated Data Calibration usually performed once per cell installation Changes with cell movement, coil movement, gain adjustments, etc. Recommended every few months for new Hybrid Polarizer.

Construction Initial Proposal: 07/07

Construction Cart Constructed: 12/07

Construction Laser Comparison: 11/07 FAP COMET

Construction Lower Gas System: 02/08 Lasers

Construction Lower Gas System: 02/08 Lasers Reduces Pressure from 3000 psi to 150 psi

Construction Lower Gas System: 02/08 Lasers

Construction Lower Gas System: 03/08

Construction Upper Gas System: 02/08 Laser 3 He fill N 2 / Vacuum

Construction Upper Gas System: 02/08 Laser To Bag 3 He fill N 2 / Vacuum

Implementation Operational Target: 04/2008

Acknowledgements Gordon Cates Peter Dolph Wilson Miller Vladimir Nelyubin Scott Rohrbaugh Jaideep Singh Al Tobias

Polarizing Spin Exchange Optical Pumping (SEOP) Collisional Mixing Rb 3 He 5P1 2 m J = 1 2 m J = + 1 2 Nonradiative Quenching D 1 Light σ + N N 3 He Rb 5S1 2 m J = 1 2 m J = + 1 2 Spin Exchange diagram Source: Singh, 2004 Spin Relaxation Rubidium energy level diagram which details optical pumping. Source: Singh, 2004

Simone- Previous Performance Cell Performance Maximum 60% 55% 50% 45% 40% Al Anna Barbara Dolly Edna Eva Gloria Simone 35% 30% 0 2 4 6 8 10 12 14 16 18 20 Predicted [K]/[Rb]

EPR Finding the Transition Frequency

AFP NMR Electronic Block Diagram (Oven Control) control control control LabVIew Computer DAQ DAQ DAQ (Oven Temp) in khz FG out sync in khz Amplifier out in Tuned RF Coils in Amp/Phase out in in Oscilloscope Pickup Coils out in Pre Amp out in in ref Lockin Amp out in Holding FG out in DC Power Supply out SHUNT in Holding Coils in Multimeter out

EPR EPR Electronic Block Diagram control control LabVIew Computer DAQ DAQ DAQ in Mod in EPR FG (MHz) out sync in MHz Amplifier out in EPR Coils in Universal Counter out Photo Diode out in ref Lockin Amp out in Mod in Feedback Chassis out in Modulation FG HI out Lo out in Oscilloscope (same as NMR)

Design of a Hybrid 3 He Polarizer: Measurement Techniques and Construction. Karen Mooney University of Virginia March 25, 2008