The colloquium given by Prof. J.-C. Peng at Purdue U. in Mar. 12, 2009

3. Neutron Electric Dipole Moment EDM has to be pointing parallel to the spin direction Mirror S + - d S - + d

5. Observation of parity violation in 60 Co beta-decay

6. No evidence for neutron EDM ! Upper limit set at 5 x 10 -20 e • cm “ The absence of an electric dipole moment in our neutron experiment and the forced postponement of our 60 Co experiments were the greatest disappointments in my research career. But by then I had realized that research scientists have both good and bad luck and productive scientists do not allow the bad luck to discourage them from further research ” N. Ramsey, 1998

9. History of Neutron EDM Measurements Current neutron EDM upper limit: < 3.0 x 10 -26 e•cm (90% C.L.) Still no evidence for neutron EDM

11. EDM measurement principle B 0 E <S z > = + h/2 <S z > = - h/2 h  (0) = -2 μ .B h  (  )= 2 (- μ .B + d n .E) h  (  )= 2(- μ .B - d n .E ) B 0 B 0 E d n defined +ve  ↑↑ -  ↑↓ = Δ  = 4 d n . E / h (slides from Karamath)

15. UCN Production in Superfluid 4 He Incident cold neutron with momentum of 0.7 A -1 (~10 -3 ev) can excite a phonon in 4 He and become an UCN (Golub and Pendlebury) neutron Superfluid 4 He UCN phonon (~1 mev)

16. UCN Production in Superfluid 4 He Magnetic Trapping of UCN at NIST (Nature 403 (2000) 62) 560 ± 160 UCNs trapped per cycle (observed) 480 ± 100 UCNs trapped per cycle (predicted)

17. A proposal for a new neutron EDM experiment Collaborating institutes: Arizona State, UC Berkeley, Caltech, Duke, Hahn-Meitner, UIUC, Indiana, Kentucky, Leiden, LANL, MIT, NCSU, ORNL, Simon-Fraser, Tennessee, Yale ( Based on the idea originated by R. Golub and S. Lamoreaux in 1994 )

20. Two oscillatory signals SQUID signal Scintillation signal

22. 3 He Distributions in Superfluid 4 He Neutron Beam 4 He Target Cell 3 He Preliminary T = 330 mK Dilution Refrigerator at LANSCE Flight Path 11a Phys. Rev. Lett. 93, 105302 (2004) Position

23. Polarized 3 He Atomic Beam Source 1 K cold head Injection nozzle Polarizer quadrupole Spin flip region Analyzer quadrupole 3 He RGA detector Produce polarized 3 He with 99.5% polarization at a flux of 2 ×10 14 /sec and a mean velocity of 100 m/sec

25. Critical dressing of neutrons and 3 He Crossing points equalize neutron and 3 He g factors: 3 He neutron Effective dressed g factors: Reduce the danger of B 0 instability between measurements 9.72 6.77 3.86 1.19

26. Los Alamos Polarized 3 He Source 1 K cold head Injection nozzle Polarizer quadrupole Spin flip region Analyzer quadrupole 3 He RGA detector B 1 dressing B 0 static Polarizer Analyzer RGA 36 in 3 He Spin dressing experiment Ramsey coils

27. Polarized 3 He source at LANL Mapping the dressing field source analyzer RGA Spin-flip coils and dressing coils used inside the solenoid. Cold head Quad separator Solenoid

28. Observation of 3 He dressed-spin effect Esler, Peng, Lamoreaux, et al. Nucl-ex/0703029 (2007)

29. Polarized 3 He relaxation time measurements H. Gao, R. McKeown, et al, arXiv:Physics/0603176 T 1 > 3000 seconds in 1.9K superfluid 4 He Acrylic cell coated with dTPB Test has also been done at 600 mK at UIUC

30. High voltage tests Goal is 50 kV/cm 200 liter LHe. Voltage is amplified with a variable capacitor 90 kV/cm is reached for normal state helium. 30 kV/cm is reached below the λ -point J. Long et al., arXiv:physics/0603231

31. SNS at ORNL First proton beam was delivered in April 2006 1.4 MW Spallation Source (1GeV proton, 1.4mA)

32. SNS Target Hall p beam FNPB-Fundamental Neutron Physics Beamline FNPB construction underway Cold beam available ~2007 UCN line via LHe ~2009

33. FNPB Beamline Double monochrometer Selects 8.9  neutrons for UCN via LHe

34. Neutron EDM Detector

35. nEDM ground “breaking” Feb. 6, 2009 (Shovel ready)

36. n-EDM Sensitivity vs Time d n < 1x10 -28 e-cm EDM @ SNS 2000 2010

41. SUSY Prediction of Neutron versus Electron EDM Barbieri et al.

42. List of Neutron EDM Experiments B = 1mG => 3 Hz neutron precession freq. d = 10 -26 e•cm, E = 10 KV/cm => 10 -7 Hz shift in precession freq. 1999 < 6.3 x 10 -26 120-150 0.01 4.5 <6.9 UCN Mag. Res. 1992 < 9.7 x 10 -26 70-100 0.018 12-15 <6.9 UCN Mag. Res. 1990 < 12 x 10 -26 70 0.01 16 <6.9 UCN Mag. Res. 1986 < 2.6 x 10 -25 50-55 0.025 12-15 <6.9 UCN Mag. Res. 1984 < 8 x 10 -25 60-80 0.01 10 <6.9 UCN Mag. Res. 1981 < 6 x 10 -25 5 0.025 20 <6.9 UCN Mag. Res. 1980 < 1.6 x 10 -24 5 0.028 25 <6.9 UCN Mag. Res. 1977 < 3 x 10 -24 0.0125 17 100 154 Beam Mag. Res. 1973 < 1 x 10 -23 0.012 14 120 154 Beam Mag. Res. 1969 < 5 x 10 -23 0.015 17 120 115 Beam Mag. Res. 1969 < 1 x 10 -21 0.0009 1.5 50 2200 Beam Mag. Res. 1968 < 3 x 10 -22 0.00625 9 140 130 Beam Mag. Res. 1967 < 8 x 10 -22 10 -7 -- 10 9 2200 Bragg Reflection 1967 < 7 x 10 -22 0.014 9 140 60 Beam Mag. Res. 1957 < 4x 10 -20 0.00077 150 71.6 2050 Beam Mag. Res. 1950 < 3 x 10 -18 10 -20 -- 10 25 2200 Scattering year EDM (e.cm) Coh. Time (s) B (Gauss) E (kV/cm) <v>(m/cm) Ex. Type

44. UIUC Test Apparatus for Polarized 3 He Relaxation at 600 mK

45. SQUIDs M. Espy, A. Matlachov ~100 cm 2 superconducting pickup coil Flux = 2 x 10 -16 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