the 3 he injection test for the nedm experiment
DESCRIPTION
The 3 He Injection Test for the nEDM Experiment. 10/2008. Xiaofeng Zhu D. Dutta, H. Gao, M. Busch, Q. Ye, T. Mestler, X. Qian, W. Zheng Duke University nEDM collaboration. Outline. Introduction Experimental setup Experimental procedure 3 He injection/collection - PowerPoint PPT PresentationTRANSCRIPT
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The 3He Injection Test for the nEDM Experiment
10/2008
Xiaofeng Zhu
D. Dutta, H. Gao, M. Busch, Q. Ye, T. Mestler, X. Qian, W. Zheng
Duke University
nEDM collaboration
2
Outline
• Introduction • Experimental setup• Experimental procedure
– 3He injection/collection– Polarization measurement
• Summary
3
Neutron EDM
• A permanent EDM dn
• The current upper limit : dn<2.9x10-26e•cm
Phys. Rev. Lett. 97, 131801 (2006) • Improve sensitivity by 2 orders of
magnitude – A mixture of ultra-cold neutrons in superfluid
4He, and polarized 3He Physics Report 237, 1 (1994)
+-s = 1/2d•E
• T and CP violation• Physics beyond SM• Baryon Asymmetry of Universe
4
Why Polarized 3He?
• Extract n precession frequency using spin dependant nuclear reaction
• Co-magnetometer
3He + n t + p (parallel) ~ 2x104 b (opposite) ~ 4x106 b
dn dipole moment d3He =0
+-EB EB
s = 1/2
n 3He
5
R&D Efforts on 3He at TUNL
• 3He T1 measurement in d-TPB coated acrylic cell filled with superfluid 4He
H. Gao, R. Golub, P. Huffman, Q. Ye, and others at TUNL
• Preparation for injection test– Collect polarized 3He in a pyrex cell filled
with superfluid 4He – Demonstrate polarization
loss is acceptable
6
Setup for 3He Injection Test
Atomic Beam Source: ~100% polarized 3He 1014 atoms/s
CryostatWith 4K 50K shield
Dilution Refrigerator
Liquid He tank at 4K
Tri-coil magnet
Solenoid magnet
7
Injection/Collection• Collection volume pre-filled
with superfluid 4He– 4He Temp. at 0.3~0.5K– 4He Volume~27cc
• 3He flux from ABS– Intensity:1014 atoms/s,– Velocity~100m/s
• After ~100s, ~1016 3He atoms are expected in superfluid 4He
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Dilutionrefrigerator
tricoil
Helium bath vesselHelium gasFilling pipe
To ABS at room temp.
50K4k
Film burner
Helium @0.35k
Pyrex cell
Heat exchanger
1.3k
0.7k
0.24k
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Cool the pyrex cell to 0.35K
• Thermal Link : OFHC copper foil– DR cooling power: 13.8mW with mixing
chamber at 0.24K
Measurement cell @.35K
Copper foil to cool the cell
DR MX at 0.24K
To ABS
DR 1K pot
Cs ring
Filling pipe for L-He
10
superfluid film suppression
• Active method– Film burner
• Passive method (optional)– Cs ring
• Non wetting of He on Cs surface
• Safety issues
April 21, 2023nEDM collaboration meeting
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Spin Rotation
• During injection, 3He travel through a curved magnetic field .– At ABS exit, 3He spins parallel to B field– Solenoid coil (20G)
• Axial field along ABS axis
– Tri-coil system (20G)• Vertically down direction
– Due to space limitation
• During injection, spins rotate by 45 deg.
Tri-coil
Solenoid co
il
4545o
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Spin Rotation: Polarization Loss
Negligible • Spin follows the field
direction– AFP condition:
• Monte-carlo simulation:– Average spin rotation ~ 3.35±0.30 deg– Polarization ~98.8%
• Low vapor density to suppress collisions
40
0
~ 625 ~ 6 10z Hz f HzB
B
3He trajectory
AFPNon AFP
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Polarization Measurement
with 1014 3He/cc• Measurement at high field ~1kG to
increase signal size
• Pulsed NMR with a single transceiver
coil
– Less sensitive to thermal displacement
– Smaller RF power
– Better signal/noise ratio expected than that
of AFP
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Field Homogeneity for pNMR
• T*2 related to longitudinal field gradient:
• The block time of pNMR is ~20μs • Transverse spin relaxation time T*
2>200 μs – Averaged within 4He liquid ( R<2.5cm,|z|<2cm)
• At 1.2kG, Field homogeneity needs to be < 27.5 ppm/cm (30mG/cm)
24 2
*2
81
175zR B
T D
Phy. Rev. A , 37 2877
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Tri-coil Design and Test• Starting with improved Helmholtz coils
– 2nd and 4th order cancellation:• I2/I1=0.53146; H/R=0.76005
– By B. Filippone, Caltech
• TOSCA Optimization – By S. Balascuta, ASU
• Numerical and analytical calculation– T*
2~2.59ms • Average over the liquid He volume, by T.Mestler,
Yale
– T*2~0.430ms
• Consider wire geometry, by W. Zheng, Duke
• Tri-coil built , axial field uniformity is ~16ppm (<27.5ppm)
I2
I1
I1
R
H
Rev. Sci. Instr. V73, 2175
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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• Cryogenic pre-
amplifer , RF shielding, etc
FID signal
2
T2 measurement on water sample
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Cryogenic pNMR system
• Faraday cage– Two tunable
capacitor – Resonant coil– Copper
[email protected]• Semi-rigid coax
– Center: Ag coated BeCu
– Dielectric: teflon– Sheath: BeCu
• From D. G. Crabb, UVA
Faraday cage
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Summary
• Magnets are ready, to be assembled with cryostat
• pNMR system under optimization
• Injection test will be carried out at LANL
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Acknowledgement
• Los Alamos National Laboratory• U.S. Department of Energy under
contract # DE-FG02-03ER41231
• Collaborating institutions– ASU, BU, Caltech, Duke, LANL, MIT,
MSU, NCSU
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Backup slides
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Cryogenics• Heat load to DR mix:~ 5mW
– 13.8mW cooling power @0.24K
– By T. Ito
– ~2.5mW from film burner– By G. Seidel
– 0.5mW pNMR and support– 1.1mW gas introduction
tube• Cs ring to slow down
superfluid flow rate– Torch to chase Cs vapor– Dry ice to condense Cs
effectively – CsN3 test will continue
• Sealing test undergoing– Pyrex to copper adapter
• 15 thermal cycles– After fail and try, kapton
gasket seals well with copper flange
Kapton gasket
Epoxy2850GT
Cs ringMade by dry ice
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Safety II: boil off of LHe within Tricoil can
• Siphon pipe to fill LHe into tricoil can
• Pipe for safety venting– Heat rate: 2 kW/m2
– Pressure drop: 5.5 psi• Gas
density@50K,1atm– By J. Long
• Venting velocity: 97m/s
• 1.375” ID, 45” length• Reynold number:
5.7x105
• resistant coefficient: 0.49
– Rupture disc@4K• Avoiding Taconis
resonance
Siphon pipe
Vacuumvent pipe
24April 21, 2023 nEDM collaboration meeting 24
Injection test cell cooling power
K24.01T K35.05 T
2T
DR Mixing Chamber
Injection test collection volume 4He4T3T
2_1R 3_2R 4_3R 5_4R
)target(35.0Tito), From(est.24.0
est.2a gPollack Fi,15.0
Boundary4He-Pyrex
W/mK001.0,cm90,mm0.1,WallPyrex
est.x.x tablePobell,002.02
daryPyrex BounGlueCopper
W/mK100,cm5.2,m9.0,busCopper
:
,mW6.0Q
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5_4
24_3
3_2
22_1
5_44_33_22_1
KKA
R
ALA
LR
AR
ALA
LR
where
RRRRRR
T
TT
totaltotal
~36 ~22 ~111 ~15
25April 21, 2023 nEDM collaboration meeting 25
Injection test vs nEDM injection
Parameter Injection Test nEDM Injection
Mechanical Scale 0.5 – 1.0 1.0
4-He Collection volume
25 cc 50 – 400 cc
Injection volume outlet NMR measurement volume Outlet valve to IV1
Injection port from ABS
Requires film burner with ID 1.05” aperture
Requires film burner with ID 1.55” aperture
Material requirements Cs coated Pyrex cell, no magnetic materials in magnetic field area
identical
Heat load ~0.5mW, conduction cooled from DR mixing chamber via 0.83 m long OFHC Copper foils
Similar heat load, ~1.2 m away from DR mixing chamber
Measurement technique
pNMR SQUIDS