1. 09.08.2011, Providence RI Paul Scherrer Institut Philipp Schmidt-Wellenburg on behalf of the nEDM collaboration An improved search of the nEDM

2. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 2/23 Baryon Asymmetry of the Universe Sakharov criteria 1.Baryon number violation 2.C and CP violation 3.Thermal non-equilibrium vs. SM expectation: Observed * : 10 ~    n B nn B * WMAP

3. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 3/23 T 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.

4. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 4/23 Standard Model: CP violation QCD vacuum: Phase of CKM matrix: Known from neutral K and B meson decays d n ≈ θ×10 -15 e·cm → θ ≈ 10 -10

5. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 5/23 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 CP odd vertex Standard Model nEDM: 10 -30 e·cm > d n >10 -32 e·cm

6. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 6/23 ++ < 1μm A brief history of nEDM searches RAL-Sussex-ILL d n < 2.9 x 10 –26 e cm C.A.Baker et al., PRL 97 (2006) 131801 Smith, Purcell, Ramsey d n < 5 x 10 –20 e cm PR 108 (1957) 120 FirstLast ~ 50 years Aimed at sensitivities at PSI: Intermediate: d n < 5 x 10 -27 e cm (95% C.L.) Finale: d n < 5 x 10 -28 e cm (95% C.L.)

7. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 7/23 The measurement technique Measure the precession frequencies in a magnetic and electric field:

8. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 8/23 The measurement technique Measure the difference of precession frequencies in parallel/anti-parallel fields: for d n <10 -26  ω/ω < 2×10 -9

9. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 9/23 The Ramsey technique Free precession at ω L Apply  /2 spin flip pulse... “Spin up” neutron... Second  /2 spin flip pulse. The Ramsey technique of separated oscillating fields B 0↑ B 0↑ + B rf B 0↑ B 0↑ + B rf Ramsey resonance curve Sensitivity:  Visibility of resonance EElectric field strength TTime of free precession NNumber of neutrons

10. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 10/23 Ultracold neutrons (UCN) storable neutrons (UCN) V E. Fermi, 1946, Ya. B. Zeldovich Sov. Phys. JETP 9, 1389 (1959) storage properties are material dependent 350 neV ↔ 8 m/s ↔ 500 Å ↔ 3 mK magnetic  60 neV/T magnetic  60 neV/T gravity 102 neV/m gravity 102 neV/m strong V F strong V F

11. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 11/23 New UCN source @PSI not yet at designed strength, ramping up

12. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 12/23 Apparatus

13. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 13/23 Apparatus 5T Magnet to spin polarize UCNs Switch to distribute the UCNs to different parts of the apparatus Spin analyzer Neutron detector Precession chamber where neutrons precesses Vacuum chamber Magnetic field coils B 0 -correction coils Electrode (upper) High voltage lead E B E~12 kV/cm B=1  T

14. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 14/23 Measuring frequencies with UCN Sensitivity: changing polarity every ~ 1.5h comparing frequency +/- polarity aimed at sensitivity  ω  60 nHz 1.5 mHz Ramsey resonance curve

15. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 15/23 The measurement technique Measure the difference of precession frequencies in parallel/anti-parallel fields: Active Stabilization and insitu field monitoring

16. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 16/23 Mercury co-magnetometer ¼ wave plate linear polarizer Hg lamps PM polarization cell HgO source B 0 ≈ 1μT Average magnetic field (volume and cycle) σ(B) ~ 20 – 50 fT Center of mass different than UCN Important Systematic effects due to magnetic field gradients τ = 140s

17. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 17/23 Corrected measurement + 12 Cesium magnetometers for field gradient measurements 50 pT

18. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 18/23 Cesium magnetometers Monitoring of vertical magnetic gradients Two cesium magnetometer arrays Stabilized laser PID phase locked DAQ 1 234 5…1112 ±140kV

19. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 19/23 Systematic effects Effect Shift (see Ref.) [10 -27 e cm] σ (see Ref.) [10 -27 e cm] σ (at PSI) [10 -27 e cm] Door cavity dipole-5.62.000.10 Other dipole fields0.06.000.40 Quadrupole difference-1.32.000.60 v  E translational 0.00.03 v  E rotational 0.01.000.10 Second-order v  E 0.00.02 Hg light shift (geo phase) 3.50.800.40 Hg light shift (direct) 0.00.20 Uncompensated B drift0.02.400.90 Hg atom EDM-0.40.300.06 Electric forces0.00.40 Leakage currents0.00.10 ac fields0.00.01 Total-3.87.191.37

20. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 20/23 Uncompensated field drift Magnetization through changing polarity

21. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 21/23 Uncompensated field drift Ramping speed = 1 kV/s Charging current = 35 nA +100 -100 E [kV] time 100 s 400-500 s

22. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 22/23 No effect is observed at the level of 2.8 fT/cm Translates into Uncompensated field drift Dedicated runs (daytime)

23. Philipp Schmidt-WellenburgAPS DPF Meeting, Brown University Providence RI, 9th August 2011 23/23 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. 09.08.2011, Providence RI Paul Scherrer Institut Philipp Schmidt-Wellenburg on behalf of the nEDM collaboration also at: 1 Paul Scherrer Institut, 2 PNPI Gatchina, 3 Eidgenössische Technische Hochschule The Neutron EDM Collaboration M. Burghoff, S. Knappe-Grüneberg, A. Schnabel, L. Trahms, J. Vogt G. Ban, Th. Lefort, Y. Lemiere, O. Naviliat-Cuncic, E. Pierre 1, 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. Zenner 1 W. Heil, H.C. Koch, A. Kraft, T. Lauer, D. Neumann, Yu. Sobolev 2 Z. Chowdhuri, M. Daum, M. Fertl 3, B. Franke 3, M. Horras 3, B. Lauss, J. Krempel, A. Mtchedlishvili, P. Schmidt-Wellenburg, G. Zsigmond C. Grab, K. Kirch 1, C. Kittel, A. Knecht, F. Piegsa 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

25. 09.08.2011, Providence RI Paul Scherrer Institut Philipp Schmidt-Wellenburg on behalf of the nEDM collaboration Thank you