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Preparation for the 3He Injection Test

11/2007 MIT/BATES

D. Dutta*, H. Gao, M. Busch, Q. Ye, X. Qian, W.

Zheng, X. Zhu (Duke University)

ASU, BU, Caltech, LANL, MIT, MSU, NCSU, SFU

And others in nEDM collaboration

*Mississippi State University.

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Outline

• Introduction• Magnets• Glassware design• Cryogenics • pNMR & Calibration• Summary

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The Goal of Injection Test

• 3He, out of ABS, collected within superfluid 4He at 0.3K

• pNMR to demonstrate that polarization loss is acceptable

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Magnets system

• Superconducting tri-coil– Central axial field uniformity<16ppm

• By Cryomagnetics

– Liquid 4He container • By MIT

• Superconducting solenoid– Ready, to be installed– design of coil support finished

• Conduction cooled» To be made by Boston Univ.

Tri-coil

Solenoid co

il

4545o

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3He Spin Rotation

• Spin follows the field direction– AFP condition:

• Monte-carlo simulation:– Average spin rotation ~ 3.35±0.30 deg– Polarization ~98.8%

40

0

~ 625 ~ 6 10z Hz f HzB

B

3He trajectory

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3He Spin Rotation Test at 300K

• Parallel mag. field – FID signal drop

by ~12.11

• Curved mag. field– FID signal drop

by ~11.9

B B

Polarization loss due to curved field is negligible

45o

1.5m

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Pyrex Collection Cell

• Pyrex collection cell– Glass to copper adaptor

• thermal cycle<20 times – Jacket design works– Coating with Cs ampule

• Started with CsN3/Cs-Spencer coating

» S. Lamoraux and E. Ihloff – Hard to control contamination

• In situ Coating with Cs ampule– Cs port not needed– Space is accessible

» J. Boissevain and M. Busch

10/2006

06/2007

11/2007

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Coating with CsN3• Hard to know/control

contamination above 400 deg C.

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Cs Coating with Cs Ampule

• Torch to chase Cs Vapor

• Cs ampule is detachable

• Coating successful

Before

After

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Cryogenics

• Filling of 4He– Jacket– 3He collection cell

» J. Boissevain

• Location of temperature sensors– Film burner

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Gas/Liquid Filling & Temperature Monitoring

1.0K--1K port of DR

0.3K --MC of DR

4.0K --Al 4K thermal shield

4.0KHe tank

Top flange at 300K

Film burner

Heater

0.5k

0.3k

Temperaturesensor

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pNMR for Injection Test

• pNMR setup at Duke– An existing magnet

modified for this test:• 1kG • Uniformity ~ 80mG/cm

– Tank circuit tuned ~ 3.89MHz

– Proton FID signal is observed at room temperature

• Comparable to 3He density during injection test

~1X1014 polarizedprotons/cc

magnetTank circuit magnet

Tecmag Apollo console

Tank circuit

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Trying to improve S/N on 1H

• Spin tipping angle at room temp.– RF duration time

• Spin echo signal– For calibration

purpose

• RF shielding– Au plated mylar

• A. Matlachov

FID signal

2

T2 measurement on water sample

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Inside dewar at 4K

1.5m, 50 ohm coax cable

Single coil setup

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21

2

( ) 1

(1 ) 50( )Q CpCsL

L Cp Cs

ohm

Tuning of Cs and Cp:

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Separate RF: Saddle Coil

• Coil design– diameter=2.54cm– length =5cm– angular aperture: 135 deg

• ( not 120 deg, due to big region of interest)

– rung width: 15 deg • Saddle coil increases the

signal size by ~1.4– Disadvantage

• Smaller RF field• Longer pulse duration

– RF heating and T2 limitation

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Polarization Calibration

• Calibration carried out after injection test

• 0.001 mol of 3He will be filled– ~5x1015 polarized atoms/cc at

0.5K, 1.2 kG

• 3He /4He gas filling panel is under construction

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Injection Test Pumping Station

• Volume from MIT

• Going to make a gas handling system

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Summary

• Magnets are ready, to be assembled with cryostat– Curved field passed spin rotation test

• Cryogenics and collection cell are under fabrication– Coating with Cs ampule

• pNMR system under optimization• Injection test will be carried out

at LANL this winter

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Thanks!