P25 EDMEDM Seminar 4/27/05 #1 Martin Cooper, Los Alamos Co-spokesperson for the EDM Project for presentation to P-25 Seminar Los Alamos, New Mexico April

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

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• 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

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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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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

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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

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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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Supersymmetry

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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

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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)

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Competition: New ILL Experiment

Funded by PPRP for construction

Also work at PSI—not considered competitiveJapan?

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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

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The Need for a Co-magnetometer?

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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

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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.

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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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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

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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

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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

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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

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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

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Dilution Refrigerator

Up to 5 mW at 120 mK

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EDM Experiment - Horiz. Section View

Light Guide

Measurement Cell

Ground Electrode

Electric Field Return

HV Generator

HV Electrode Support

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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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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

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High Voltage Multiplier

Capacitive Multiplier

HV Test Stand

q=CV

d = 0.5 5 cmHV = 50 500 kV

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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

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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

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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

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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

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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)

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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

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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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Experimental Layout in Area B

UCN

Coat withUCN absorber

Switch

Diamond coatedguide

Area B Setup

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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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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

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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

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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

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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

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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

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Saddle cos Coil

Shield dimensions (identical):

r = 9.33cm, ℓ = 91.44cm, t = 60 mils

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Magnetic MaterialsMagnetic Field Uniformity

Room Temperature

1.2 K

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Magnetic Materials

Required

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SQUID Low-Field NMR

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-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

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Topics Skipped

• 3He-spin relaxation• Most systematic errors• Bottle storage time• Dressed spin

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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

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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)

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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

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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.

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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

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Monte Carlo calculation of shift

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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

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3He Relaxation

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3He Relaxation

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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

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3He Distributions in Superfluid 4He

Neutron Beam

Position

4He

TargetCell

3He

Dilution Refrigerator atLANSCE Flight Path 11a

Resistive Heater

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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

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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

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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

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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%

Documents

P25 EDMEDM Seminar 4/27/05 #1 Martin Cooper, Los Alamos Co-spokesperson for the EDM Project for presentation to P-25 Seminar Los Alamos, New Mexico April