p25 edmedm seminar 4/27/05 #1 martin cooper, los alamos co-spokesperson for the edm project for...
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P25
EDMSeminar 4/27/05 #1
Martin Cooper, Los AlamosCo-spokesperson for the EDM Project
for presentation to
P-25 SeminarLos Alamos, New Mexico
April 27, 2005
A New Search for theElectric Dipole Moment of the Neutron
P25
EDMSeminar 4/27/05 #2
• Motivation• Related Experiments• The Technique• Systematic Errors• Realization• Research and Development
A Matter of Time Reversal:A New Search for the
Electric Dipole Moment of the Neutron
Outline
P25
EDMSeminar 4/27/05 #3
EDM CollaborationD. Budker, A. Sushkov
University of California at Berkeley, Berkeley, CA 94720, USAB. Filippone, R. McKeown, B. Plaster
California Institute of Technology, Pasadena, CA 91125, USAD. Dutta, H. Gao, M. Kidd, K. Kramer, X. Qian, Q. Ye, X. Zong
Duke University, Durhan NC 27708, USA R. Golub, K. Korobkina, F. Mezei
Hahn-Meitner Institut, D-14109 Berlin, GermanyJ. Doyle, L. Yang
Harvard University, Cambridge, MA 02138, USAJ. Fuzi
Hungarian Academy of Sciences, Budapest, HungaryD. Beck, A. Esler, D. Hertzog, P. Kammel, J.-C. Peng, S. Williamson, J. Yoder
University of Illinois, Urbana-Champaign, IL 61801, USAJ. Butterworth
Air Liquide - Advanced Technology Division, BP 15 - 38360 Sassenage, FranceG. Frossati
University of Leiden, NL-2300 RA Leiden, The NetherlandsP. Barnes, J. Boissevain, M. Cooper, M. Espy, S. Lamoreaux, J. Long,
C.-Y. Lu, A. Matlachov, R. Mischke, S. Penttila, W. Sondheim, J. Torgerson, S. WilburnLos Alamos National Laboratory, Los Alamos, NM 87545, USA
T. GentileNational Institute of Standards and Technology, Gaithersburg, MD 20899, USA
C. Gould, P. Huffman, A. YoungNorth Carolina State University, Raleigh, NC 27695, USA
V. Cianciolo, T. ItoOak Ridge National Laboratory, Oak Ridge, TN 37831, USA
G. Archibald, M. HaydenSimon-Fraser University, Burnaby, BC, Canada V5A 1S6
D. McKinseyYale University, New Haven, CT 06520, USA
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EDMSeminar 4/27/05 #4
http://p25ext.lanl.gov/edm/edm.htmlLA-UR 02-2331
A New Search for theNeutron Electric Dipole
Moment
Funding Pre-proposal
submitted to
The Department of Energy
prepared by
The EDM CollaborationMarch 28, 2002
LA-UR 05-0829 Recent Progress and Design Changes
February 1, 2005
P25
EDMSeminar 4/27/05 #5
The Permanent EDM of the Neutron
• A permanent EDM d
• The current value is < 6 x 10-26 e•cm (90% C.L.)
• We hope to obtain roughly < 10-28 e•cm with UCN in superfluid He
+-s = 1/2d•E
P25
EDMSeminar 4/27/05 #6
Theory and Experiment
10-20 10-22 10-24 10-26 10-28 10-30 10-32 10-34 10-36 10-38 e-cm
Electromagnetic
Left-right symmetric
Cosmology
Standard model
Multi-Higgs
SUSY φ ~ α/π
excluded ILL SNS'50 '68 '84 '05 '16
Theory as distributions
EDM rules out theories
SM leaves room for discovery
Strong CP parameter
SUSY GUT
Electro-weak Baryogenesis
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EDMSeminar 4/27/05 #8
B - B Asymmetry in the Universe
Before PhaseTransition
After PhaseTransition
Today
N
0
1010
BB BB BB
10 10N
N B
1NN
NNA
BB
BBBB10 10
2
1
0
2
1
P25
EDMSeminar 4/27/05 #9
Status of EDM Measurements(e-cm)
Fundamental Particles n ILL |dn| < 1.2 x 10-25 PNPI |dn| < 1.1 x 10-25 ILL (199Hg) |dn| < 6(2) x 10-26 ILL (No E) |dn| < (1) x 10-27 PSI |dn| < (1) x 10-27 SNS (3He) |dn| < (1) x 10-28 p |dp| < 10-22 p- assym. |d| < 1.5 x 10-16 e g-2 |de| < 4 x 10-16 reactor exp. |dF3| < 2 x 10-20 g-2 |d| < 7 x 10-19
|d| < 10-24 (Z +-) |d| < 4.5 x 10-18
Paramagnetic Atoms H Lamb shift |de| < 2 x 10-13 Fe+3 d3/2 |de| < 2 x 10-22 Rb 5s |da| < 1.2 x 10-23 |de| < 5 x 10-25 Cs 6s |da| < 1.3 x 10-23 |de| < 1 x 10-25 Tl 5p1/2 |da| < 1 x 10-24 |de| < 2 x 10-27 Diamagnetic Atoms 129Xe Wash. |da| < 2 x 10-26 |dn| < 2 x 10-23 199Hg Wash. |da| < 2 x 10-28 |dn| < 2 x 10-26 Polar Molecules YF |de| < 4x10-25(10-28)
PbO |de| < (10-30)
P25
EDMSeminar 4/27/05 #10
Competition: New ILL Experiment
Funded by PPRP for construction
Also work at PSI—not considered competitiveJapan?
P25
EDMSeminar 4/27/05 #11
The Basic Technique
+-
E
s = 1/2 dipole moment dn
Look for a precessionfrequency d
Figure of Merit for EDM Experiments ~ NE 125
E 5E 5 N 125 N
B
P25
EDMSeminar 4/27/05 #13
3He Magnetometry
dn dipole moment d3 =0
Look for a difference in precessionfrequency n - 3 d dependent on Eand corrected for temporal changes in 3
+-
EB EB
s = 1/2
n 3He
P25
EDMSeminar 4/27/05 #14
3He-Dopant as an Analyzer3He + n t + p (parallel) < 102 b
(opposite) ~ 104 b
UCN loss rate ~1-p3•pn = 1-p3pn cos(n-
3)B0t
|n-
3| = |n|/10
3He concentration must be adjusted to keepthe lifetime reasonable for a given valueof the 3He polarization.
The proper value for the fractionalconcentration x = Atoms-3He/Atoms-4He ~10-10.
P25
EDMSeminar 4/27/05 #15
4He as a Detector3He + n t + p
t + p share 764 keV of kinetic energy.
The emitted light (~3 photons/keV) is in the XUV ~ 80 nm.
A wavelength shifter (TPB) is used to change it to the blue,where it can be reflected and detected.The walls and the wavelength shifter must be made ofmaterials that do not absorb or depolarize neutrons or 3He.
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EDMSeminar 4/27/05 #16
The Signal
-15
-10
-5
0
5
10
15
599 600 601 602 603 604 605 606
Time (sec)
Am
plit
ud
e
-15
-10
-5
0
5
10
15
603.4 603.6 603.8 604 604.2 604.4 604.6
Time (sec)
Am
plit
ud
e3He(n,p)t Scintillation Light ~ (3 - n )
SQUID ~ 3
~ dnE
P25
EDMSeminar 4/27/05 #17
Experiment Cycle
T = 40 - 450 s UCN from Cold n
T = 0 - 40 s Fill with 4He and 3He
T = 460 - 960 s Precession about E & B
T = 450 - 460 s /2 pulse
T = 960 - 1000 s Recycle He
L He
8.9 Å neutrons
Refrigerator
UCN ~ 500 Åone polarization state absorbed
Phonon
(UCN)=P
t
p
3He
E , B
L He
3He E , B
Fill Lines L He
E , B
3He
n
L He
n
3He
E , B
t
p
XUV
XUV
Deuterated TPBon Walls
Light to PMT
Light to PMT
SQUID
Emptying Lines
E , B
P25
EDMSeminar 4/27/05 #18
Gradient interference with E x v field
/
/
0
2
0r
r
B
cEaRBB
arBr Radial gradient
v x E field changes sign with direction
c
EaR22
10-28 e-cm requires a < 10 G/m3He depolarization gradient requirement < a
P25
EDMSeminar 4/27/05 #19
Dimensional Requirements
B/B < 10-3 Depolarization Length > 2.5 m
E > 50 kV/cm Sensitivity Radius > 0.3 m
V > 0.7 m3 = 700 l
P25
EDMSeminar 4/27/05 #20
EDM Experiment - Vertical Section View
Dilution Refrigerator (DR: 1 of 2)
Upper Cryostat Services Port
DR LHe Volume 450 Liters
3He Polarized Source
He Purifier Assembly
3He Injection Volume
Central LHe Volume (300mK, ~1000 Liters)
Re-entrant Insert for Neutron Guide
Lower Cryostat
Upper Cryostat
3He Injection Volume cosθ Magnet
5.6m
4 Layer μ-metal Shield
P25
EDMSeminar 4/27/05 #22
EDM Experiment - Horiz. Section View
Light Guide
Measurement Cell
Ground Electrode
Electric Field Return
HV Generator
HV Electrode Support
P25
EDMSeminar 4/27/05 #23
Coil and Shield Nesting
Inner-Dressing & Spin-Flip Coil
Outer Dressing Coil
50K Shield
4K Shield
Superconducting Lead Shield
Ferromagnetic Shield
B0 cosθ Magnet
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EDMSeminar 4/27/05 #24
Upper/Lower Cryostat Interface
Inner cosθ Dressing Coil
Central Helium Volume
3He Injection Region cosθ Coil
DR 1
DR 2
Turbo Pump
He Recirculation Bellows Actuators
HV Generator Actuators
3He Injection Region
He Safety Vent
Helium Purifier
Actuator Support
P25
EDMSeminar 4/27/05 #25
High Voltage Multiplier
Capacitive Multiplier
HV Test Stand
q=CV
d = 0.5 5 cmHV = 50 500 kV
P25
EDMSeminar 4/27/05 #26
Kerr Effect-Liquid He
Measurement:
K = (1.43±0.02(stat)±0.04(sys))
x10-20 (cm/V)2
Theoretical value
(1s, 2s, 2p levels):
K = 1.7x10-20 (cm/V)2
500 s
HV Stability
P25
EDMSeminar 4/27/05 #27
Ultra-cold NeutronsUltra-cold neutrons (UCN) have a low enough energy to be bottled. Their wavelength is long enough to feel a generally repulsive force (totally internally reflected) from certain materials as described by their Fermi potential. The minimum wavelength is material dependent; e.g. a good one is 58Ni. Properties: UF ~ 200 neV v ~ 5 m/s ~ 500 Å mg ~ 100 neV/m ~ 60 neV/T UCN can be bottled by UCN can be polarized by • materials • magnetic fields • the gravitational potential • gradient magnetic fields • a gradient magnetic field • 3He
P25
EDMSeminar 4/27/05 #28
Superthermal Source of UCNs
Uw = 200 neVULHe = 20 neV
Quasi two-levelsystem with singlephonon upscatteringsuppressed by a largeBoltzman factor.
up ~ 100 T-7 from 2-
phonon upscattering
P25
EDMSeminar 4/27/05 #29
Superthermal Source of UCNs
L He
8.9 Å neutronsRefrigerator
UCN ~ 500 ÅPhonon
(UCN)=P
P 7.2d2
dd1
w3
Verified by NIST n-lifetime experiment!
SNS cold source = 9 x 1012 n/cm2-s-sr after the monochromator10-cm x 12-cm supermirror guide, = 0.01 str.P = 2.2 UCN/cm3-s ~ 500 s
UCN ~ 1100/cm3
275 times current ILL UCN density.Cell volume is 4000 cm3 in each of two cells.Velocity selection an advantage of a pulsed source
P25
EDMSeminar 4/27/05 #30
Monochromator
Ballistic Neutron Guide Section
Neutron Beam Splitter- Polarizer Guide Section
Fundamental Neutron Physics Hall
Dilution Refrigerator Pump Packages
1000 Liter Dewar
Neutron Guide (LANL, ORNL)
P25
EDMSeminar 4/27/05 #31
Neutron State Selector -Splitter
1o
7.2 m
Natural Nickel Guide - m= 1
Supermirror Guide - m= 3
Polarizing Beam Splitter - m=2 used at BENSC
25 cm
B
B
1o 3o
Unpolarized neutron m=1Spin up neutronSpin down neutron
EDM cells7.5 cm wide50 cm long
25 cm
Ballistic guide
2o
P25
EDMSeminar 4/27/05 #32
Lifetime in a Bottle
upholewn 111111
3
where n is the neutron lifetime,
w is the wall lifetime, hole is the losses through a hole 3 is absorption lifetime, up is upscattering lifetime. Preliminary result > 100s
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EDMSeminar 4/27/05 #33
Experimental Layout in Area B
UCN
Coat withUCN absorber
Switch
Diamond coatedguide
Area B Setup
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EDMSeminar 4/27/05 #34
Storage CellThe cell - 90 cm x 19 cm ID - 25.6 liters - @10 UCN/cc gives 2.5 x 105
- acrylic coated with d-styrene - can be cooled to ~4 K
Option for dTPB
Storage Cell
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EDMSeminar 4/27/05 #35
Storage Time
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
0 5 10 15 20 25 30 35 40 45 50
Time from Switch Opening (min.)
Co
un
ts in
n D
etec
tor/
min
.
Delay 11
Delay 7
Delay 21
Delay 17
Delay 4
Storage Time
1/Fill Time = Production Rate - Loss Rate
Absorption Time
1/Detector Loss Rate
Storage Time
Storage Time
P25
EDMSeminar 4/27/05 #36
ResultsDiffusion Coefficient of 3He in 4He
0.00001
0.0001
0.001
0.01
0.1
1
10
100
1000
10000
100000
1000000
10000000
100000000
0.1 1 10
Temperature (K)
(cm
2/s
)
Beenakker et al.
This Experiment
T-7
3= n
P25
EDMSeminar 4/27/05 #37
4He Purifier
McClintock Heat Flush Technique
First sample measured at ANL - 3He/4He <10-12
3He/4Hemixture
Pure 4HeResistiveheater wrappedon capillary
Flow control valve
Phonons
T = 1.2 K
P25
EDMSeminar 4/27/05 #38
4He Purification
3He velocity must be sufficient to overcome the binding energy to thesuperfluid 4He, i.e
0.3 K < T < 0.5 K
based on the diffusion coefficientmeasurement.
The pump is a charcoal trap
P25
EDMSeminar 4/27/05 #39
3He Atomic Beam Polarizer
Device commissioned
Flux 4 x 1014 atoms/s
Average velocity ~150 m/s
Polarization measurements(99.6 ± 0.25)%
Loading time300 s
P25
EDMSeminar 4/27/05 #40
Saddle cos Coil
Shield dimensions (identical):
r = 9.33cm, ℓ = 91.44cm, t = 60 mils
P25
EDMSeminar 4/27/05 #44
-decay and -ray Separation30
25
20
15
10
5
0
Aft
erp
uls
es
per
main
puls
e
3.5nVolt sec3.02.52.01.51.00.50.0
Main Pulse area
90mK, neutron count rate 700 Hz
n(3He,t)p
e
P25
EDMSeminar 4/27/05 #45
Topics Skipped
• 3He-spin relaxation• Most systematic errors• Bottle storage time• Dressed spin
P25
EDMSeminar 4/27/05 #46
SNS Risk Analysis ReprisedQuantity Symbol Design Degraded EDM
LossEDM Limit [95% CL]
Wall Loss Time w >2,000 s 500 s 1.8
Particle ID 30:1 4:1 3.0
Background / Signal 2:1 5:1 1.63He Relaxation Time 3 30,000 s 10,000 s 1.3
3He Initial Polarization P3 99% 99.6% 1.0
SQUID Noise 1 0 10 0 1.4
Trapped Fields B/B 10-3 3 x 10-3 1.5
Electric Field E 50 kV/cm 50 kV/cm 1.0
Quadrature 4.8 15 x 10-29 e*cm
Murphy's Law (4 worst)
13 38 x 10-29 e*cm
P25
EDMSeminar 4/27/05 #47
Systematic Errorsv x E Field reversal to 1%, v3=vn
gravitational fractionation 1 mm by size limitation
Sensitivity Limitationspolarization relaxation uniform fields & wall coatingsbackgrounds particle ID & shielding & beamSQUID noise magnetic & mechanical isolationN beam & cell designE LHe properties
SNS: (300 days over 3 years)dn < 10-28 (95% CL)
P25
EDMSeminar 4/27/05 #48
Some Paraphrases"Of the three experiments, EDM is the hardest but addresses the most interesting physics"
Pendelbury Committee
"EDM is the experiment with the greatest discovery potential for the new fundamental-neutron-science beam line at the Spallation Neutron Source."
Report to NSAC, Subcommittee on Fundamental Physics with Neutrons (2003) 1.
"The EDM collaboration has carried out a very good R&D program. They should brag about it more."
Allison Lung, LANL Cost and Schedule Review
"The EDM experiment can be done for $16 ± 2 M."Allison Lung, LANL Cost and Schedule Review
"The R&D program is well matched to a construction start in FY'07. DOE and NSF should not induce the project to lose momentum by delaying the construction start."
Dave DeMille, LANL Cost and Schedule Review
P25
EDMSeminar 4/27/05 #49
Summary
• A neutron EDM experiment with 10-28 e-cm sensitivity is strongly motivated by the search for a new source of T violation and its impact on cosmology and supersymmetry.
• The R&D program has made considerable progress in defining the apparatus as well as understanding and overcoming the experimental challenges.
• The collaboration is poised to start construction in 2007, begin data taking in 2011, and have final results in 2016.
P25
EDMSeminar 4/27/05 #50
Principle of Dressed Spin
)/(' rfrfo BJ
n 1.13
'' 3 n 1.1/ rfrfn B when
We want Brf >> B0 (1-10 mG) so Brf is around 1 G,rf /2 near 3 kHz
RF field must be homogeneous at the 0.1-1% level
Heating and gradients due to eddy currents present design challenges
Eliminates need for SQUID magnetometers and potentially increasesthe sensitivity of the experiment
P25
EDMSeminar 4/27/05 #52
SENSITIVITY
mF T
2m
2m
22T
Fm3T
e2T2T2Te1PV
TT12
4
1f
(f)=39.0 nHz with Tm=500 s, TF=1000 s and 3=1000 s dn < 9 x 10-28 ecm (95% CL) -- with -decay background only
Evaluate with P=1/cc/s, V=4 l, T=100 d, E=50 kV/cm, 2 cells
(f)=19.5 nHz with Tm=500 s, TF=1000 s and 3=1000 s dn < 4.5 x 10-28 ecm (95% CL) -- with -decays eliminated
(f)=8.2 nHz with with Tm=2850 s, TF=1375 s and 3=2000 s dn < 2 x 10-28 ecm (95% CL) -- with -decays eliminated
P25
EDMSeminar 4/27/05 #55
SQUIDs M. Espy, A. Matlachov ~100 cm2 superconducting pickup coil
Flux = 2 x 10-16 Tm2 = 0.1 0 Noise = 4 m0/Hz1/2 at 10Hz ~ T1/2
2.5 m0/Hz1/2
P25
EDMSeminar 4/27/05 #56
3He Distributions in Superfluid 4He
Neutron Beam
Position
4He
TargetCell
3He
Dilution Refrigerator atLANSCE Flight Path 11a
Resistive Heater
P25
EDMSeminar 4/27/05 #57
Diffusion Coefficient
Heater resistor
Pencilcold-neutronbeam
4He:3He = 10,000:1
3He free region
•3He(n,p)t measures path length of 3He from scintillations from stopping p and t•More heat implies smaller path length
Three component Liquid: Superfluid 4He, normal 4He, concentration X of 3He
0 XDvX n
DL 2/2
P25
EDMSeminar 4/27/05 #58
Systematic ErrorsGravitational Shift
Due to difference in the effective temperature of the UCN and3He atoms, there can be a displacement between the centers-of–gravity; this places a constraint on systematic magnetic field gradients
kTghnm
h 32
h = 1.5 mm for UCN if h = 10 cm and Tn = 5 mK
P25
EDMSeminar 4/27/05 #59
Electric Field Systematic Effects sys EvB
0/2)γv(
31 fEsysf 3.0δ requires cm2810 E/Ee
For atoms contained in a cell, 0v
However, the effective field adds in quadrature with the applied static magnetic field. The net effect depends on the time between wall collisions, but in the case where there are many precessions between wall collisions,
Spiral Leakage Currents
5 x 10-29 e-cm requires < 1 nA leakage (1/4 loop)
HVB
P25
EDMSeminar 4/27/05 #60
Pseudomagnetic Field
• The polarized 3He creates an effective magnetic field for the UCN, corresponding to a Larmor frequency of about 1 mHz
• The anticipated sensitivity per cycle is about 1 mHz• In order to eliminate this potential noise source, the spin flip
must be controlled with an accuracy of 0.1%