An improved search of the nEDM

1. An improved search of the nEDM

2. SM expectation: Sakharov criteria Observed*: • Baryon number violation • C and CP violation • Thermal non-equilibrium - n n vs. - B 10 B ~ 10 n g Baryon Asymmetry of the Universe *WMAP

3. CP violation and EDM • CP violation so far only in weak decays • Might help explain BAU matter/anti-matter problem • Excellent probe for physics beyond the Standard Model(complementary to LHC) A nonzero particle EDM violates P, T and, assuming CPT conservation, also CP. T

4. Standard Model: CP violation • QCD vacuum: • Phase of CKM matrix: dn≈ θ×10-15 e·cm → θ ≈ 10-10 Known from neutral K and B meson decays

5. nEDM from CKM Matrix • No tree level contribution • No first loop contribution • No pure week interaction two loop contribution • Only gluon two loop contribution→ strongly suppressed Standard Model nEDM: 10-30 e·cm > dn >10-32 e·cm CP odd vertex

6. +  < 1μm A brief history of nEDM searches Aimed at sensitivities at PSI:Intermediate: dn < 5 x 10-27 e cm (95% C.L.)Finale:dn< 5 x 10-28 e cm(95% C.L.) ~ 50 years First Last Smith, Purcell, Ramsey dn < 5 x 10–20 e cmPR 108 (1957) 120 RAL-Sussex-ILL dn < 2.9 x 10–26e cmC.A.Baker et al., PRL 97 (2006) 131801

7. The measurement technique Measure the precession frequencies in a magnetic and electric field:

8. The measurement technique Measure the difference of precession frequencies in parallel/anti-parallel fields: fordn<10-26 ω/ω< 2×10-9

9. Ramsey resonance curve Sensitivity: • Visibility of resonanceE Electric field strengthT Time of free precessionN Number of neutrons The Ramsey technique The Ramsey technique of separated oscillating fields “Spin up” neutron... B0↑ Apply /2 spin flip pulse... B0↑ + Brf Free precessionat ωL B0↑ Second /2 spin flip pulse. B0↑ + Brf

10. gravity 102 neV/m V strong VF 350 neV ↔ 8 m/s ↔ 500 Å ↔ 3 mK magnetic 60 neV/T storage properties are material dependent E. Fermi, 1946 ,Ya. B. Zeldovich Sov. Phys. JETP 9, 1389 (1959) Ultracold neutrons (UCN) storable neutrons (UCN)

11. New UCN source @PSI not yet at designed strength, ramping up

12. Apparatus

13. Apparatus High voltage lead Vacuum chamber Precession chamberwhere neutrons precesses Electrode (upper) B E E~12 kV/cm B=1 T Magnetic field coilsB0-correction coils Switchto distribute the UCNs todifferent parts of the apparatus Spin analyzer 5T Magnetto spin polarize UCNs Neutron detector

14. Measuring frequencies with UCN Ramsey resonance curve • changing polarity every ~ 1.5h • comparing frequency +/- polarity • aimed at sensitivity ω  60 nHz Sensitivity: 1.5 mHz

15. The measurement technique Measure the difference of precession frequencies in parallel/anti-parallel fields: Active Stabilization and insitu field monitoring

16. Mercury co-magnetometer • Average magnetic field (volume and cycle) • σ(B)~ 20 – 50 fT • Center of massdifferent than UCN • Important Systematic effectsdue to magnetic field gradients PM τ = 140s polarization cell B0 ≈ 1μT ¼ wave platelinear polarizer Hg lamps HgO source

17. Corrected measurement 50 pT + 12 Cesium magnetometers for field gradient measurements

18. Cesium magnetometers • Two cesium magnetometer arrays • Stabilized laser • PID phase locked DAQ Monitoring of vertical magnetic gradients ±140kV 1 2 3 4 5 … 11 12

19. Systematic effects

20. Uncompensated field drift Magnetization through changing polarity

21. Uncompensated field drift 400-500 s +100 E [kV] 100 s time -100 Ramping speed = 1 kV/s Charging current = 35 nA

22. Uncompensated field drift No effect is observed at the level of 2.8 fT/cm Translates into No effect is observed at the level of 2.8 fT/cm Dedicated runs (daytime)

23. Conclusion • UCN source is ramping up → first data this year (50 nights) • Reduction of main systematic effects • Further improvements on systematic effects winter shut-down 2011-2012 • 200 nights of data in 2012-2013

24. Physikalisch Technische Bundesanstalt, Berlin Laboratoire de Physique Corpusculaire, Caen Institute of Physics, Jagiellonian University, Cracow Henryk Niedwodniczanski Inst. Of Nucl. Physics, Cracow Joint Institute of Nuclear Reasearch, Dubna Département de physique, Université de Fribourg, Fribourg Laboratoire de Physique Subatomique et de Cosmologie, Grenoble Biomagnetisches Zentrum, Jena Katholieke Universiteit, Leuven Inst. für Kernchemie, Johannes-Gutenberg-Universität, Mainz Inst. für Physik, Johannes-Gutenberg-Universität, Mainz Paul Scherrer Institut, Villigen Eidgenössische Technische Hochschule, Zürich M. Burghoff, S. Knappe-Grüneberg, A. Schnabel, L. Trahms, J. Vogt G. Ban, Th. Lefort, Y. Lemiere, O. Naviliat-Cuncic, E. Pierre1, G. Quéméner K. Bodek, St. Kistryn, G. Wyszynski, J. Zejma A. Kozela N. Khomutov M. Kasprzak, P. Knowles, A. Weis, Z. Grujic G. Pignol, D. Rebreyend S. Afach, G. Bison N. Severijns, R. Chankova, S. Roccia C. Plonka-Spehr, J. Zenner1 W. Heil, H.C. Koch, A. Kraft, T. Lauer , D. Neumann, Yu. Sobolev2 Z. Chowdhuri, M. Daum, M. Fertl3 , B. Franke3, M. Horras3, B. Lauss, J. Krempel, A. Mtchedlishvili, P. Schmidt-Wellenburg, G. Zsigmond C. Grab,K. Kirch1, C. Kittel, A. Knecht, F. Piegsa The Neutron EDM Collaboration also at: 1Paul Scherrer Institut, 2PNPI Gatchina, 3Eidgenössische Technische Hochschule

25. Thank you