1. Villigen, 22.02.2012 Status of the nEDM measurement Progress 2011 PSI Proposal R–05–03.1 Philipp Schmidt-Wellenburg on behalf of the nEDM collaboration

2. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 T CP violation and EDM → CP so far only in weak decay → Excellent probe for physics beyond the Standard Model → Might explain BAU matter/anti-matter problem A nonzero particle EDM violates P, T and, assuming CPT conservation, also CP.

3. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 The measurement technique Measure the difference of precession frequencies in parallel/anti-parallel fields: for d n <10 -26  ω < 60 nHz RAL-Sussex-ILL : d n < 2.9 x 10 –26 e cm C.A.Baker et al., PRL 97 (2006) 131801

4. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 The Ramsey technique Free precession at ω L Apply  /2 spin flip pulse... “Spin up” neutron... Second  /2 spin flip pulse. 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

5. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 Reminder Phase I: Operate and improve OILL@ILL (all cycles 2008) Moved OILL March 2009 Design of n2EDM, related R&D Phase II: Operate OILL@PSI (2009-2013) Sensitivity goal: 5x10 -27 ecm Design of n2EDM, construction and setup R&D Phase III: Operate n2EDM (2014-2017) Sensitivity goal: 5x10 -28 ecm   

6. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 Magnetic fields Magnetic field control: Four layer mu-metal shield 33 trim coils (inside shield) Six compensation coils (around apparatus) Mercury comagnetometer Cesium magnetometer array

7. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 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

8. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 Mercuy comagnetometer

9. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 Hg contaminated Geometric phase Hg under pressure Sudden collapse 1 st change of electrodes 2 nd change of electrodes 3 rd change of electrodes

10. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 Cesium magnetometers Monitoring of vertical magnetic gradients Two cesium magnetometer arrays Stabilized laser PID phase locked DAQ 1 234 5…1112 ±140kV

11. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 Magnetic field gradients Most important source of systematic effects → Field mapping → Online Cs-OPM measurement → Combination of online information and field maps

12. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 Geometric phase Gradient applied with trim coils: 0 – 4nT/cm E-field: ±100 kV/12cm For each setting: B0 up and B0 down ~30 polarity changes Gradient: Cs-OPM measurement ~20h per point

13. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 Results geometric phase For B0 up: (-9.69 ± 0.33) * 10 -27 e cm @ 10 pT/cm For B0 down: (9.94 ± 0.25) * 10 -27 e cm @ 10 pT/cm Data are in agreement within 15 % to the calculations of Pendlebury 1.15 * 10 -26 e cm @ 10 pT/cm Discrepancy is still investigated, gradients from fluxgate maps seem to agree better…

14. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 Cs-OPM response method Measure the response of each Cs-OPM for current changes for all trim coils → Response Matrix A mn → Invert Matrix → Calculate currents for each coil to get desired field value

15. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 Cs-OPM response method

16. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 Ultra cold neutrons Regular pulses (every 480s for 4s) 900 000 UCN in direct measurements 16 000 UCN counted after 4s storage in precession chamber

17. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 UCN Detector Counts neutrons Can distinguish gammas Sends UCN counts to main DAQ

18. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 UCN Spin performance Discrepancy for α 0 can be explained with UCN counting method Manual adjusted emptying sequence No manual tuning of trim coils (only Cs response)

19. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 UCN emptying curve Low α 0 for T 1 and T 2 indication for strong depolarization (SC magnet → ~100%) τ flip = 236 s τ loss =16.5 s τ ↓ = 163 s τ ↑ = 16.9 s N = 29185 α 0 = 0.999 Best fit to data

20. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 UCN Ramsey cycles Ramsey curve taken with 250 s precession time N 0 = 1205 α 0 = -0.46

21. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 UCN nEDM run

22. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 Outlook Characterize UCN switch properties (April: storage and transmission measurements at ILL) Recover excellent Hg performance (bake out electrodes, insulator ring) Upgrade Cs-Array to 8 HV, 10 ground sensors Characterize important UCN parameters with high UCN density ( α, τ, Δh, T 1, T 2 ) 150 nights nEDM-Data (July-December, 2012)

23. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 - movable 5 layer cubic shielding (design discussion with companies ongoing) - active vibration compensation Phase III

24. Philipp Schmidt-WellenburgVilligen, BVR 22.02.2012 also at: 1 Paul Scherrer Institut, 2 PNPI Gatchina, 3 Eidgenössische Technische Hochschule, 4 KEK The Neutron EDM Collaboration M. Burghoff, A. Schnabel, J. Vogt G. Ban, V. Helaine 1, Th. Lefort, Y. Lemiere, O. Naviliat-Cuncic, E. Pierre 1, G. Quéméner K. Bodek, St. Kistryn, G. Wyszynski 3, J. Zejma A. Kozela N. Khomutov Z. Grujic, M. Kasprzak, P. Knowles, H.C. Koch, A. Weis G. Pignol, D. Rebreyend S. Afach, G. Bison J. Becker, N. Severijns, R. Chankova S. Roccia C. Plonka-Spehr, J. Zenner 1 W. Heil, 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, K. Mishima 4, A. Mtchedlishvili, P. Schmidt-Wellenburg, G. Zsigmond K. Kirch 1, F. Piegsa, D. Ries 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 Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, Orsay Inst. für Kernchemie, Johannes-Gutenberg-Universität, Mainz Inst. für Physik, Johannes-Gutenberg-Universität, Mainz Paul Scherrer Institut, Villigen Eidgenössische Technische Hochschule, Zürich