Design of a Hybrid 3He Polarizer:Measurement Techniques and Construction

Karen Mooney

University of Virginia

March 25, 2008

Polarizer Basics

Mooney

Mooney

New Polarizer Advancements

More Gas

• 3.0L/day Vs

1.0L/day

Higher Polarization

•60% Vs 40%

•Rb-K Hybrid Cell

•Narrowed Diode Lasers

Enhanced Diagnostics

• AFP NMR w/ EPR

calibration

Vs

Pulse NMR w/ Water

calibration

Nuclear Magnetic Resonance (NMR)

Mooney

Helium

Spin

Holding

Field

H

Measuring

Polarization

•Polarized 3He nuclei are aligned

with an external magnetic field

•He Nuclear Spins are “flipped” by

applying a transverse RF Field

•Faraday Induction signal detected in

mutually perpendicular coils

•Signal detected is proportional to 3He

polarization

Nuclear Magnetic Resonance (NMR)

Mooney

Helium

Spin

Holding

Field

H

Measuring

Polarization

RF

Field

H1

•Polarized 3He nuclei are aligned

with an external magnetic field

•He Nuclear Spins are “flipped” by

applying a transverse RF Field

•Faraday Induction signal detected in

mutually perpendicular coils

•Signal detected is proportional to 3He

polarization

Adiabatic Fast Passage

Mooney

Helium

Spin

RF

Field

H1

Holding

Field

H

Measuring

Polarization

Adiabatic Fast Passage

Mooney

Helium

Spin

RF

Field

H1

Holding

Field

H

Measuring

Polarization

AFP

Helium

Spin

RF

Field

H1

Holding

Field

H

MooneyMeasuring

Polarization

AFP

MooneyMeasuring

Polarization

Helium

Spin

RF

Field

H1

Holding

Field

H

AFP

Helium

Spin

RF

Field

H1

Holding

Field

H

MooneyMeasuring

Polarization

AFP

Measuring MooneyMeasuring

Polarization

Helium

Spin

RF

Field

H1

Holding

Field

H

AFP

Measuring MooneyMeasuring

Polarization

Helium

Spin

RF

Field

H1

Holding

Field

H

AFP

Measuring MooneyMeasuring

Polarization

Helium

Spin

RF

Field

H1

Holding

Field

H

AFP

Measuring MooneyMeasuring

Polarization

Helium

Spin

RF

Field

H1

Holding

Field

H

AFP

Measuring MooneyMeasuring

Polarization

Helium

Spin

RF

Field

H1

Holding

Field

H

AFP

Measuring MooneyMeasuring

Polarization

Helium

Spin

RF

Field

H1

Holding

Field

H

AFP

Measuring MooneyMeasuring

Polarization

Helium

Spin

RF

Field

H1

Holding

Field

H

AFP

Measuring MooneyMeasuring

Polarization

Helium

Spin

RF

Field

H1

Holding

Field

H

AFP

MooneyMeasuring

Polarization

Helium

Spin

RF

Field

H1

Holding

Field

H

AFP

Helium

Spin

Holding

Field

H

MooneyMeasuring

Polarization

Adiabatic- Field is swept slowly so that the

spin can follow it

Fast- The Field is swept quickly enough so

that the spins do not relax in the low field

region.

-Holding Field (H)

-RF Field H1(ω)

- - Pick Up Coils

-EPR Coil

EPR Photo Diode

AFP Schematic

MooneyMeasuring

Polarization

xz

y

-Holding Field (H)

-RF Field H1(ω)

- - Pick Up Coils

-EPR Coil

EPR Photo Diode

AFP Schematic

MooneyMeasuring

Polarization

xz

y

AFP Schematic

-Holding Field (H)

-RF Field H1(ω)

- - Pick Up Coils

-EPR Coil

EPR Photo Diode

MooneyMeasuring

Polarization

xz

y

Sample Spin Up Taken 01/2008Sample NMR Signal

Measuring

Lock-In Signal A “Spin Up” Fit

AFP Signal

MooneyMeasuring

Polarization

Electron Paramagnetic ResonanceMooneyMeasuring

Polarization

EPR- Measuring Frequency ShiftMooneyMeasuring

Polarization

EPR- Measuring Frequency ShiftMooneyMeasuring

Polarization

EPR- Measuring Frequency ShiftMooneyMeasuring

Polarization

EPR- Monitoring FrequencyMooneyMeasuring

Polarization

Mooney

Helium

Spin

RF

Field

H1

Holding

Field

H

Measuring

Polarization

EPR- Reversing 3He Polarization

EPR Schematic

-Holding Field (H)

-RF Field H1(ω)

- - Pick Up Coils

-EPR Coil

EPR Photo Diode

MooneyMeasuring

Polarization

xz

y

-Holding Field (H)

-RF Field H1(ω)

- - Pick Up Coils

-EPR Coil

EPR Photo Diode

EPR Schematic

MooneyMeasuring

Polarization

xz

y

Mooney

Main Optical Pumping Oven

Measuring

Polarization

Mooney

Main Optical Pumping Oven

Measuring

Polarization

Mooney

Main Optical Pumping Oven

Measuring

Polarization

Mooney

Main Optical Pumping Oven

Measuring

Polarization

Mooney

Main Optical Pumping Oven

Measuring

Polarization

Calculating Polarization

Calibration Procedure

•Take NMR

•Do EPR

•Take NMR

•Calculate PHe

•Average NMR Signals

•Get %/mV Calibration

MooneyMeasuring

Polarization

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.

MooneyMeasuring

Polarization

MooneyConstruction

Initial Proposal: 07/07

MooneyConstruction

Initial Proposal: 07/07

MooneyConstruction

Initial Proposal: 07/07

MooneyConstruction

Initial Proposal: 07/07

MooneyConstruction

Initial Proposal: 07/07

Mooney

Cart Constructed: 12/07

Construction

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Laser Comparison: 11/07

Construction

FAP COMET

MooneyLower Gas System: 02/08

Construction

Lasers

MooneyLower Gas System: 02/08

Construction

Lasers

MooneyLower Gas System: 02/08

Construction

Reduces

Pressure

from 3000 psi

to 150 psi

Lasers

MooneyLower Gas System: 02/08

Construction

Lasers

MooneyLower Gas System: 02/08

Construction

Lasers

MooneyLower Gas System: 02/08

Construction

Lasers

ConstructionLower Gas System: 03/08

Mooney

Upper Gas System: 02/08

Laser

3He fill N2 / Vacuum

MooneyConstruction

Upper Gas System: 02/08

Laser

3He fill N2 / Vacuum

MooneyConstruction

Upper Gas System: 02/08

Laser

3He fill N2 / Vacuum

MooneyConstruction

Upper Gas System: 02/08

Laser

3He fill N2 / Vacuum

MooneyConstruction

To Bag

MooneyImplementation

Operational Target: 04/2008

Mooney

Acknowledgements

Gordon Cates

Peter Dolph

Wilson Miller

Vladimir Nelyubin

Scott Rohrbaugh

Jaideep Singh

Al Tobias

Mooney

Spin Exchange Optical Pumping (SEOP)

Rubidium energy level diagram which details optical pumping. Source: Singh, 2004

Collisional Mixing

Spin Relaxation

5P1

2

5S1

2

QuenchingNonradiative

D1 Light

mJ = +12

mJ = +12mJ = −

12

mJ = −12

σ+

N

N

Rb3He

3He Rb

Spin Exchange diagram Source: Singh, 2004

Polarizing

Cell Performance

30%

35%

40%

45%

50%

55%

60%

0 2 4 6 8 10 12 14 16 18 20

Predicted [K]/[Rb]

Ma

xim

um

Po

lariz

atio

n

Al

Anna

Barbara

Dolly

Edna

Eva

Gloria

Simone

Simone- Previous PerformanceMooney

EPR MooneyFinding the Transition Frequency

Tuned RF Coilsin

Pickup Coilsout

kHz Amplifierin out

kHz FGin out

sync

Amp/Phasein out

Oscilloscopein

Lockin Ampin

ref

outPre Amp

in out

LabVIew Computercontrol

Holding Field Coilsin

DC Power Supplyin out

Holding FGin out

Multimeterin out

SHUNT

DAQ

DAQ

control

in

NMR Electronic Block Diagram

DAQcontrol(Oven Control) (Oven Temp)

in

AFP Mooney

EPR Coilsin

Photo Diodeout

MHz Amplifierin out

EPR FG (MHz)in out

sync

Universal Counterin out

Feedback Chassisin

Mod in

outLockin Amp

in out

LabVIew Computercontrol

Modulation FGin HI out

DAQ

DAQ

control

EPR Electronic Block Diagram

ref

Mod in

Lo outOscilloscope (same as NMR)

in

DAQ

EPR Mooney