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 27, 2005 A New Search for the Electric Dipole Moment of the Neutron

P25 EDMEDM Seminar 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 EDMEDM Seminar 4/27/05 #3 EDM Collaboration D. Budker, A. Sushkov University of California at Berkeley, Berkeley, CA 94720, USA B. Filippone, R. McKeown, B. Plaster California Institute of Technology, Pasadena, CA 91125, USA D. 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 Berlin, Germany J. Doyle, L. Yang Harvard University, Cambridge, MA 02138, USA J. Fuzi Hungarian Academy of Sciences, Budapest, Hungary D. Beck, A. Esler, D. Hertzog, P. Kammel, J.-C. Peng, S. Williamson, J. Yoder University of Illinois, Urbana-Champaign, IL 61801, USA J. Butterworth Air Liquide - Advanced Technology Division, BP Sassenage, France G. Frossati University of Leiden, NL-2300 RA Leiden, The Netherlands P. 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. Wilburn Los Alamos National Laboratory, Los Alamos, NM 87545, USA T. Gentile National Institute of Standards and Technology, Gaithersburg, MD 20899, USA C. Gould, P. Huffman, A. Young North Carolina State University, Raleigh, NC 27695, USA V. Cianciolo, T. Ito Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA G. Archibald, M. Hayden Simon-Fraser University, Burnaby, BC, Canada V5A 1S6 D. McKinsey Yale University, New Haven, CT 06520, USA

P25 EDMEDM Seminar 4/27/05 #4 LA-UR A New Search for the Neutron Electric Dipole Moment Funding Pre-proposal submitted to The Department of Energy prepared by The EDM Collaboration March 28, 2002 LA-UR Recent Progress and Design Changes February 1, 2005

P25 EDMEDM Seminar 4/27/05 #5 The Permanent EDM of the Neutron A permanent EDM d The current value is < 6 x ecm (90% C.L.) We hope to obtain roughly < ecm with UCN in superfluid He +- s = 1/2dE

P25 EDMEDM Seminar 4/27/05 #6 Theory and Experiment 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

P25 EDMEDM Seminar 4/27/05 #7 Supersymmetry

P25 EDMEDM Seminar 4/27/05 #8 B - B Asymmetry in the Universe Before Phase Transition After Phase Transition Today N 0 10  BB

P25 EDMEDM Seminar 4/27/05 #9 Status of EDM Measurements (e-cm)

P25 EDMEDM Seminar 4/27/05 #10 Competition: New ILL Experiment Funded by PPRP for construction Also work at PSI—not considered competitive Japan?

P25 EDMEDM Seminar 4/27/05 #11 The Basic Technique + - E s = 1/2 dipole moment d n Look for a precession frequency  d Figure of Merit for EDM Experiments ~  125 E  5E   5  N  125 N B

P25 EDMEDM Seminar 4/27/05 #12 The Need for a Co-magnetometer?

P25 EDMEDM Seminar 4/27/05 #13 3 He Magnetometry d n dipole moment d 3 =0 Look for a difference in precession frequency  n -  3   d dependent on E and corrected for temporal changes in  EBEB s = 1/2 n 3 He

P25 EDMEDM Seminar 4/27/05 #14 3 He-Dopant as an Analyzer

P25 EDMEDM Seminar 4/27/05 #15 4 He as a Detector 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 of materials that do not absorb or depolarize neutrons or 3He.

P25 EDMEDM Seminar 4/27/05 #16 The Signal 3 He(n,p)t Scintillation Light ~ (  3 -  n ) SQUID ~  3 ~ d n E

P25 EDMEDM Seminar 4/27/05 #17 Experiment Cycle T = s UCN from Cold n T = s Fill with 4 He and 3 He T = s Precession about E & B T = s  /2 pulse T = s Recycle He L He 8.9 Å neutrons Refrigerator UCN ~ 500 Å one polarization state absorbed Phonon  (UCN)=P  t p 3 He E, B L He 3 He E, B Fill Lines L He E, B 3 He n L He n 3 He E, B t p XUV  Deuterated TPB on Walls Light to PMT SQUID Emptying Lines E, B

P25 EDMEDM Seminar 4/27/05 #18 Gradient interference with E x v field Radial gradient v x E field changes sign with direction e-cm requires a < 10  G/m 3 He depolarization gradient requirement < a

P25 EDMEDM Seminar 4/27/05 #19 Dimensional Requirements  B/B 2.5 m E > 50 kV/cmSensitivityRadius > 0.3 m V > 0.7 m 3 = 700 l

P25 EDMEDM Seminar 4/27/05 #20 EDM Experiment - Vertical Section View Dilution Refrigerator (DR: 1 of 2) Upper Cryostat Services Port DR LHe Volume 450 Liters 3 He Polarized Source He Purifier Assembly 3 He 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 EDMEDM Seminar 4/27/05 #21 Dilution Refrigerator Up to 5 mW at 120 mK

P25 EDMEDM Seminar 4/27/05 #22 EDM Experiment - Horiz. Section View Light Guide Measurement Cell Ground Electrode Electric Field Return HV Generator HV Electrode Support

P25 EDMEDM Seminar 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 B 0 cosθ Magnet

P25 EDMEDM Seminar 4/27/05 #24 Upper/Lower Cryostat Interface Inner cosθ Dressing Coil Central Helium Volume 3 He 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 EDMEDM Seminar 4/27/05 #25 High Voltage Multiplier Capacitive Multiplier HV Test Stand q=CV d = cm HV = kV

P25 EDMEDM Seminar 4/27/05 #26 Kerr Effect-Liquid He Measurement: K = (1.43±0.02 (stat) ±0.04 (sys) ) x (cm/V) 2 Theoretical value (1s, 2s, 2p levels): K = 1.7x (cm/V) s HV Stability

P25 EDMEDM Seminar 4/27/05 #27 Ultra-cold Neutrons

P25 EDMEDM Seminar 4/27/05 #28 Superthermal Source of UCNs

P25 EDMEDM Seminar 4/27/05 #29 Superthermal Source of UCNs L He 8.9 Å neutrons Refrigerator UCN ~ 500 Å Phonon  (UCN)=P  Verified by NIST n- lifetime experiment! SNS cold source  = 9 x n/cm 2 -s-sr after the monochromator 10-cm x 12-cm supermirror guide,  = 0.01 str. P = 2.2 UCN/cm 3 -s  ~ 500 s  UCN ~ 1100/cm times current ILL UCN density. Cell volume is 4000 cm 3 in each of two cells. Velocity selection an advantage of a pulsed source

P25 EDMEDM Seminar 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 EDMEDM Seminar 4/27/05 #31 Neutron State Selector -Splitter 1o1o 7.2 m Natural Nickel Guide - m= 1 Supermirror Guide - m= 3 Polarizing Beam Splitter - m=2 used at BENSC 25 cm B B 1o1o 3o3o Unpolarized neutron m=1 Spin up neutron Spin down neutron EDM cells 7.5 cm wide 50 cm long 25 cm Ballistic guide 2o2o

P25 EDMEDM Seminar 4/27/05 #32 Lifetime  in a Bottle

P25 EDMEDM Seminar 4/27/05 #33 Experimental Layout in Area B UCN Coat with UCN absorber Switch Diamond coated guide Area B Setup

P25 EDMEDM Seminar 4/27/05 #34 Storage Cell The cell - 90 cm x 19 cm ID liters UCN/cc gives 2.5 x acrylic coated with d-styrene - can be cooled to ~4 K Option for dTPB Storage Cell

P25 EDMEDM Seminar 4/27/05 #35 1/Fill Time = Production Rate - Loss Rate Absorption Time 1/Detector Loss Rate Storage Time

P25 EDMEDM Seminar 4/27/05 #36 Results T -7  3 =  n

P25 EDMEDM Seminar 4/27/05 #37 4 He Purifier McClintock Heat Flush Technique First sample measured at ANL - 3 He/ 4 He < He/ 4 He mixture Pure 4 He Resistive heater wrapped on capillary Flow control valve Phonons T = 1.2 K

P25 EDMEDM Seminar 4/27/05 #38 4 He Purification 3 He velocity must be sufficient to overcome the binding energy to the superfluid 4 He, i.e 0.3 K < T < 0.5 K based on the diffusion coefficient measurement. The pump is a charcoal trap

P25 EDMEDM Seminar 4/27/05 #39 3 He Atomic Beam Polarizer Device commissioned Flux 4 x atoms/s Average velocity ~150 m/s Polarization measurements (99.6 ± 0.25)% Loading time 300 s

P25 EDMEDM Seminar 4/27/05 #40 Saddle cos  Coil Shield dimensions (identical): r = 9.33cm, ℓ = 91.44cm, t = 60 mils

P25 EDMEDM Seminar 4/27/05 #41 Magnetic Materials Magnetic Field Uniformity Room Temperature 1.2 K

P25 EDMEDM Seminar 4/27/05 #42 Magnetic Materials   Required 

P25 EDMEDM Seminar 4/27/05 #43 SQUID Low-Field NMR

P25 EDMEDM Seminar 4/27/05 #44  -decay and  -ray Separation n( 3 He,t)p e

P25 EDMEDM Seminar 4/27/05 #45 Topics Skipped 3 He-spin relaxation Most systematic errors Bottle storage time Dressed spin

P25 EDMEDM Seminar 4/27/05 #46 SNS Risk Analysis Reprised QuantitySymbolDesignDegradedEDM Loss EDM Limit [95% CL] Wall Loss Time ww >2,000 s500 s1.8 Particle ID30:14:13.0 Background / Signal2:15: He Relaxation Time 33 30,000 s10,000 s1.3 3 He Initial PolarizationP3P3 99%99.6%1.0 SQUID Noise 1  0 10  Trapped Fields  B/B x Electric FieldE50 kV/cm 1.0 Quadrature4.815 x e*cm Murphy's Law (4 worst) 1338 x e*cm

P25 EDMEDM Seminar 4/27/05 #47 Systematic Errors v x EField reversal to 1%, v 3 =v n gravitational fractionation1 mm by size limitation Sensitivity Limitations polarization relaxationuniform fields & wall coatings backgroundsparticle ID & shielding & beam SQUID noisemagnetic & mechanical isolation N  beam & cell design ELHe properties SNS: (300 days over 3 years) d n < (95% CL)

P25 EDMEDM Seminar 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 EDMEDM Seminar 4/27/05 #49 Summary A neutron EDM experiment with 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 EDMEDM Seminar 4/27/05 #50 Principle of Dressed Spin when We want B rf >> B 0 (1-10 mG) so B rf 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 increases the sensitivity of the experiment

P25 EDMEDM Seminar 4/27/05 #51 Monte Carlo calculation of shift

P25 EDMEDM Seminar 4/27/05 #52 SENSITIVITY   (f)=39.0 nHz with T m =500 s, T F =1000 s and  3 =1000 s  d n < 9 x e  cm (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 T m =500 s, T F =1000 s and  3 =1000 s  d n < 4.5 x e  cm (95% CL) -- with  -decays eliminated   (f)=8.2 nHz with with T m =2850 s, T F =1375 s and  3 =2000 s  d n < 2 x e  cm (95% CL) -- with  -decays eliminated

P25 EDMEDM Seminar 4/27/05 #53 3 He Relaxation

P25 EDMEDM Seminar 4/27/05 #54 3 He Relaxation

P25 EDMEDM Seminar 4/27/05 #55 SQUIDs M. Espy, A. Matlachov ~100 cm 2 superconducting pickup coil Flux = 2 x Tm 2 = 0.1  0 Noise = 4 m  0 /Hz 1/2 at 10  Hz ~ T 1/2 2.5 m  0 /Hz 1/2

P25 EDMEDM Seminar 4/27/05 #56 3 He Distributions in Superfluid 4 He Neutron Beam Position 4 He Target Cell 3 He Dilution Refrigerator at LANSCE Flight Path 11a Resistive Heater

P25 EDMEDM Seminar 4/27/05 #57 Diffusion Coefficient Heater resistor Pencil cold-neutron beam 4 He: 3 He = 10,000:1 3 He free region 3 He(n,p)t measures path length of 3 He from scintillations from stopping p and t More heat implies smaller path length Three component Liquid: Superfluid 4He, normal 4He, concentration X of 3He

P25 EDMEDM Seminar 4/27/05 #58 Systematic Errors Gravitational Shift Due to difference in the effective temperature of the UCN and 3 He atoms, there can be a displacement between the centers- of–gravity; this places a constraint on systematic magnetic field gradients  h = 1.5 mm for UCN if h = 10 cm and T n = 5 mK

P25 EDMEDM Seminar 4/27/05 #59 Electric Field Systematic Effects For atoms contained in a cell, 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 e-cm requires < 1 nA leakage (1/4 loop) HV B

P25 EDMEDM Seminar 4/27/05 #60 Pseudomagnetic Field The polarized 3 He 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%