Philip Harris University of Sussex (for the EDM Collaboration) The Neutron EDM Experiments at the ILL

P. Harris University of Sussex Highlights New (but preliminary) limit: |d n | < 3.1 x e.cm 1. nEDM “Classic” 2. CryoEDM Under development: 100x improved sensitivity

P. Harris University of Sussex Electric Dipole Moments Separation between +,- charge centres EDMs are P odd T odd Complementary approach to study of CPv E + d n = d n s

P. Harris University of Sussex SM EDM predictions very small so no SM background to worry about Beyond SM predictions typ greater... so EDMs are excellent probe of BSM CPv SM parameterisation of CPv inadequate to explain baryon asymmetry Strong CP Problem:  s < rads CP violation & the neutron EDM

P. Harris University of Sussex d q, d q ~ (loop factor)  sin  CP c 2  mqmq Implications for SUSY quark electric dipole moments qq  gaugino squark quark color dipole moments qq g gaugino squark CP phase from soft breaking naturally O(1) scale of SUSY breaking naturally ~200 GeV naturally ~  d u,d, d u,d ~ 3  10  24 cm naturally c n and Hg experiments give d u < 2  10  25 d d < 5  10  26 d u < 3  10  26 d d < 3  10  26 c c ~ 100 times less!  > 2 TeV ?  CP < ?

P. Harris University of Sussex History Factor 10 every 8 years on average Now CryoEDM

P. Harris University of Sussex Measurement principle (  ) – (  ) = – 4 E d/ h assuming B unchanged when E is reversed. B0B0 E = + h/2 = - h/2 h (0) h (  ) h (  ) B0B0 B0B0 E Energy resolution of our detector: eV Use NMR on ultracold neutrons in B, E fields.

P. Harris University of Sussex Apparatus Neutron storage chamber HV feedthru B-field coils

P. Harris University of Sussex nEDM measurement Look for n freq changes correlated with changes in E Electric Field + -

P. Harris University of Sussex Mercury co-magnetometer Compensates B drift...

P. Harris University of Sussex  B = T Raw neutron frequency Corrected frequency Precession frequency (Hz) Run duration (hours) nEDM measurement

P. Harris University of Sussex Neutron EDM results (binned) Current limit set here Stat. limit now 1.54 x e.cm

P. Harris University of Sussex Systematics Consider Should have value 1 R is shifted by magnetic field gradients Plot EDM vs measured R-1:

P. Harris University of Sussex Systematics Magnetic field down

P. Harris University of Sussex Systematics Magnetic field up

P. Harris University of Sussex Geometric phase and, from Special Relativity, extra motion-induced field Two effects: J.M. Pendlebury et al., PRA (2004)

P. Harris University of Sussex Geometric phase BrBr BrBr B net BvBv BvBv BvBv... so particle sees additional rotating field Frequency shift  E Looks like an EDM Bottle (top view)

P. Harris University of Sussex Results R-1 EDM 0 B down B up The answer? Nearly...

P. Harris University of Sussex Results R-1 EDM 0 Small dipole/quadrupole fields can pull lines apart & add GP shifts B up B down

P. Harris University of Sussex Results R-1 EDM 0 Small dipole/quadrupole fields can pull lines apart & add GP shifts B up B down Measure and apply correction...difficult!

P. Harris University of Sussex Error budget Statistical1.54E-26 e.cm Dipole & quadrupole shifts6E-27 e.cm Enhanced GP dipole shifts~4E-27 e.cm (E x v)/c 2 from translation1E-27 e.cm (E x v)/c 2 from rotation1E-27 e.cm Light shift: direct8E-28 e.cm B fluctuations7E-28 e.cm E forces – distortion of bottle4E-28 e.cm Tangential leakage currents1E-28 e.cm AC B fields from HV ripple<1E-28 e.cm Light shift: GP effects8E-28 e.cm

P. Harris University of Sussex PRELIMINARY Results New (preliminary) limit: |d n | < 3.1 x e.cm (90% CL) d n = (-0.31  1.54  1.00) x e.cm Preprint expected soon

P. Harris University of Sussex CryoEDM 100-fold improvement in sensitivity! n = 8.9 Å; E = 1.03 meV Landau-Feynman dispersion curve for 4 He excitations Dispersion curve for free neutrons R. Golub and J.M. Pendlebury Phys. Lett. 53A (1975), Phys. Lett. 62A (1977) More neutrons Higher E field Better polarisation Better NMR time

P. Harris University of Sussex CryoEDM overview Neutron beam input Transfer section Cryogenic Ramsey chamber

P. Harris University of Sussex Cryogenic Ramsey chamber Superfluid He HV electrode n storage cells

P. Harris University of Sussex CryoEDM Turns on October 2006

P. Harris University of Sussex Conclusions EDM “Classic”: new (preliminary) limit, factor 2 improvement CryoEDM coming soon – 100x more sensitive Watch this space!